Craftsman 28984, 28980, 28906, 28981 User Manual

Professional Shop Manual

Electric Module

28906,28980, 28981,28984

NOTE: These materials are for use by trained technicians who are experienced in the service and repair of outdoor power equipment of the kind described in this publication, and are not intended for use by untrained or inexperienced individuals. These materials are intended to provide supplemental information to assist the trained technician. Untrained or inexperi- enced individuals should seek the assistance of an experienced and trained professional. Read, understand, and follow all instructions and use common sense when working on power equipment. This includes the contents of the product's Oper- ators Manual, supplied with the equipment. No liability can be accepted for any inaccuracies or omission in this publication, although care has been taken to make it as complete and accurate as possible at the time of publication. However, due to the variety of outdoor power equipment and continuing product changes that occur over time, updates will be made to these instructions from time to time. Therefore, it may be necessary to obtain the latest materials before servicing or repairing a product. The company reserves the right to make changes at any time to this publication without prior notice and without incurring an obligation to make such changes to previously published versions. Instructions, photographs and illustrations used in this publication are for reference use only and may not depict actual model and component parts.

MTD Products Inc. - Product Training and Education Department

,FORM NUMBER-769-06468

09/2010

Table of Contents

Introduction ....................................................................................................... 1

Professional Shop manual intent ...................................................................... 1

Fasteners ......................................................................................................... 1

Assembly .......................................................................................................... 1

Description of the GT series ............................................................................. 2

Model and Serial Numbers ............................................................................... 2

Precautions ...................................................................................................... 2

RMC Module .................................................................................................... 3

Key switch ........................................................................................................ 3

RMC module .................................................................................................... 5

RMC module plug test (electric PTO) ............................................................... 7

RMC module plug test (manual PTO) .............................................................. 9

Electric PTO switch ......................................................................................... 11

PTO relay ........................................................................................................ 11

PTO switch (manual PTO) .............................................................................. 12

Brake switch (manual PTO) ............................................................................ 12

Brake switch (electric PTO) ............................................................................. 13

Park brake switch ............................................................................................ 14

Reverse Safety Switch .................................................................................... 14

Seat Safety Switch .......................................................................................... 15

Starter solenoid ............................................................................................... 16

Fuse ................................................................................................................ 17

Electrical diagnosis .......................................................................................... 17

Electrical environment: AC Vs. DC .................................................................. 19

Types of circuits .............................................................................................. 21

Series ........................................................................................................... 21

Parallel ......................................................................................................... 21

Series/parallel .................................................................................................. 22

Shorts ........................................................................................................... 22

Opens ........................................................................................................... 22

Increased resistance ....................................................................................... 22

The Tools ........................................................................................................ 22

Equipment that may be useful: ........................................................................ 22

Digital Multi-meter ........................................................................................... 23

Wiring diagram or schematic ........................................................................... 24

Fused jumper wires ......................................................................................... 24

Test lights (high impedance) ........................................................................... 24

Ammeters and specialized charging system testers

Batteries .......................................................................................................... 27

Battery Testers: ............................................................................................... 29

Testing the battery: .......................................................................................... 29

Voltage Drop Test ........................................................................................... 33

Testing switches .............................................................................................. 35

Relay ............................................................................................................... 36

Diodes ............................................................................................................. 37

Schematics ...................................................................................................... 39

CRAFTSMAN

INTRODUCTION

ELECTRICALSYSTEM

INTRODUCTION

This module is divided into four sections:

Section 1: About this module and precautions Section 2: Components

This section will describe the location and opera- tion of the electrical components on the tractor. Where appropriate, some disassembly or com- ponent removal instructions will be included.

Section 3: Diagnostic Techniques This section will cover basic tools, techniques, and methodology for diagnosing electrical issues

on the tractor. A lot of the information in this sec- tion can be applied to other equipment.

Section 4: Schematics

Professional Shop manual intent

This Manual is intended to provide service dealers with an introduction to the mechanical aspects of the new

900 series tractor.

Detailed service information about the engine

will be provided by the engine manufacturer, in

most cases.

Disclaimer: This manual was written using first gener- ation tractors. The information contained in this shop manual is correct at the time of writing. Both the prod- uct and the information about the product are subject to change without notice.

About the text format:

• Bullet points: indicate sub-steps or points. Disclaimer: This Professional Shop Manual is

intended for use by trained, professional technicians.

• Common sense in operation and safety is assumed.

In no event shall MTD be liable for poor text interpretation, or poor execution of the proce-

dures described in the text. If the person using this manual is uncomfortable

with any procedures they encounter, they should

seek the help of a qualified technician.

Fasteners

Most of the fasteners used on the tractor are sized in fractional inches. Some are metric. For

this reason, wrench sizes are frequently identi-

fied in the text, and measurements are given in

U.S. and metric scales. If a fastener has a locking feature that has worn,

replace the fastener or apply a small amount of releasable threadlocking compound such as Loctite® 242 (blue).

Some fasteners like cotter pins are single-use items that are not to be reused. Other fasteners

such as lock washers, retaining rings, and inter- nal cotter pins (hairpin clips) may be reused if they do not show signs of wear or damage. This manual leaves that decision to the judgement of

the technician.

Assembly

NOTE: is used to point-out information that is

relevant to the procedure, but does not fit as a step in the procedure.

CAUTION: Indicates a potentially hazardous sit- uation that, if not avoided, may result in minor or moderate injury. It may also be used to alert against unsafe practices.

DANGER: Indicates an imminently hazardous situation that, if not avoided, will result in death

or serious injury. This signal word is to be lim- ited to the most extreme situations.

WARNING: Indicates a potentially hazardous

situation that, if not avoided, could result in death of serious injury.

Torque specifications may be noted in the part of the text that covers assembly, they may also be summa- rized in tables along with special instructions regarding locking or lubrication. Whichever method is more appropriate will be used. In many cases, both will be used so that the manual is handy as a quick-reference guide as well as a step-by-step procedure guide that does not require the user to hunt for information.

The level of assembly instructions provided will be determined by the complexity and of reassembly, and by the potential for unsafe conditions to arise from mis- takes made in assembly.

Some instructions may refer to other parts of the man- ual for subsidiary procedures. This avoids repeating the same procedure two or three times in the manual.

CRAFTSMAN

Description of the GT series

This tractor platform introduced in the 2010 season.. See Figure 1.1.

Figure 1.1

• New stronger frame

• New hood and grill designs

• Bumper

• A new 2 blade 46" deck

• Tighter turning radius Model and Serial Numbers

The model and serial number tag can be found under the seat. See Figure 1.2.

The model number is 13AR91PP099 The break down of what the number mean is as follows:

13......................... lawn tractor

...A....................... sales level

......R..................... engine code

........9................... tractor series

.......... 1................ drive system

............ R............. hood style

............... P........... deck

................... 099 ....customer number

The serial number is 1J050H30003. The serial number reads as follows:

1........................... engineering level

..J......................... month of production (J = October)

.....05 .................... day of the month

.........0.................. last digit of the year

........... H................ plant it was built in

.............. 3............. assembly line number

................. 0003 ..... number of unit built

Precautions

CAUTION: Before disconnecting any electrical

component, take precautions to prevent the component or the wires attached to it from short- ing out. The most effective means of doing this is to disconnect the battery ground cable from the negative battery terminal.

Figure 1.2

The serial number is located to the right of the model number as shown above. See Figure 1.2.

CAUTION: Unless performing tests that require

the electrical system to be in operation, discon- nect the negative cable from the battery before doing any work to the electrical system of the

tractor.

ELECTRICAL SYSTEM

ELECTRICALSYSTEM

COMPONENTS RMC Module

The RMC module contains electronic logic circuits. When diagnosing anything that is connected to the RMC module, a high impedance test light or a high impedance digital multi-meter (DMM) must be used. The amperage draw of a standard incandescent test light may over-burden some internal electronic circuits, burning-out the module.

It is typical when industries shift from electro- mechanical to electronic controls that diagnosis shifts from tracing through a number of indepen- dent circuits to checking the in-puts to and out- puts from a central processor. This is similar to, but much less complex than the transition that the auto industry made with the conversion to

fuel injection in the 1980s.

NOTE: The starter safety circuit has no connec- tion to the RMC module.

The only one switch in the safety circuit that is capable of turning-off the engine works through

the RMC module. It is still important to be familiar with the workings

of the individual components of the electrical system, but some of them can now be checked

from a central point on the tractor. This makes

life easier on the technician, frequently making it unnecessary to connect to difficult to reach switches in the preliminary stages of trouble- shooting.

The function of individual safety switches can be seen as providing information "inputs" to the

RMC module. The next part of this section gives a detailed

description of the electrical components on this tractor, their function in the system, and their physical location on the tractor. Armed with this information and the proper tools, a technician should be able to efficiently diagnose most elec- trical problems.

Key switch

The Key Switch is similar to those used in a variety of MTD applications since 1999. The difference in this case is that it is incorporated in the same housing as the RMC module; the two items are not available sepa- rately. See Figure 7.1.

RMC Module

Key Switch

Figure 7.1

In the OFF position, continuity can be found between the M, G, and A1 terminals.

See Figure 7.2.

Key Switch Schematic

Off

S B

Run w/RMC

Figure 7.2

Start

Run

CRAFTSMAN

M is connected to the magneto by a yellow wire, G is connected to ground by a green wire, and

A1 is connected to the after fire solenoid. NOTE: In the OFF position, the magneto primary

windings are grounded, disabling the ignition

system. The altenator output is shorted to ground and the after fire solenoid looses its power from the B terminal. This turns-off the fuel supply.

Symptom-enqine runs with key in OFF position: The key switch is not completing the path to ground either because of an internal fault or a

bad ground connection elsewhere in the har-

ness. Check continuity between M, G, and A1 terminals with key switch in OFF position.

Check green wire for continuity to ground.

Symptom-loud "BANG" when key is turned to

the OFF position: The after-fire solenoid is not

closing, either because it is physically damaged

or the power is not being turned off. Check for

power at the solenoid. Check continuity between

G and A1 terminals. Check for no continuity

between A1 and the B terminals.

NOTE: If the engine is at an idle when the key is

turned off, fuel is drawn into the engine through

the idle ports of the carburetor by-passing the fuel shut off solenoid. The raw fuel will travel

through the engine and ignite in the muffler

causing an after fire.

Symptom-Enqine runs 3-5 seconds after key is

turned to OFF position: The after-fire solenoid is

turning-off the fuel supply, but the ignition is con-

tinuing to operate. Check continuity between the

M and G terminals in the OFF position. Check

continuity from yellow wire connection all the way to the spade terminal on the magneto.

In the START position, continuity can be found

between B, S, and A1 terminals.

Battery power from the B terminal is directed to

the start circuit through the S terminal and to the

after fire solenoid through A1.

Symptom-No crank and no starter solenoid click: Power is not getting to the trigger spade on the starter solenoid. Test for proper battery volt- age. Then check for power where the fused red

wire with white trace connects to the B terminal.

Check for continuity between B and S terminals in START position. If power is getting to the S terminal in the START position, the problem lies

down-stream in the starter circuit; Check conti- nuity from the orange wire on the S terminal to

the orange wire with white trace on the trigger spade on the starter solenoid. If it is broken, trace through the brake and PTO switches.

Symptom-No crank, solenoid click: The problem lies in the heavy-gauge side of the starter circuit; battery cables, starter cable, solenoid, or ground

issue.

Symptom-Crank, spark, but not fuel: First test for power at the solenoid, if no power then check for continuity from B to A1 in the START posi-

tion. If power is reaching the red wire that con-

nects to the A1 terminal in the start position, the

problem lies down-stream of the key switch. A

handy quick-check is to apply power to the red wires where they connect to the S terminal

(whole circuit) or directly to the after fire solenoid

to listen for the audible "click" that it makes when functioning.

Symptom-Crank, but no spark: This is a highly

unlikely scenario. If it occurs after a key switch

has been changed independently of the RMC

module, this would arouse suspicion that the wrong key switch was installed. Otherwise, the

problem lies elsewhere in the safety circuits or

engine. Do not over-look the possibility of a bad

magneto or chafed ground lead within the

engine harness.

In the NORMAL RUN position (green zone), the

B and A1 terminals should have continuity. Once

the engine is running, the alternator produces

current that tracks-back to charge the battery,

via the red wire connected to the B terminal.

Symptom-Battery does not charqe: Follow the

engine manufacturer's recommendations for

testing alternator output. If alternator output is

getting to and through the key switch, but not

reaching the battery, the fuse may have blown

after start-up. A blown fuse will disable the

starter circuit. A simple quick-test for the pres-

ence of alternator output at the battery is to

check across the battery posts for DC voltage.

ELECTRICAL SYSTEM

Symptom-After fire solenoid does not work:

enqine starts and dies: The after fire solenoid is powered directly by the red wire from the B ter-

minal of the key switch, and should operate independently of anything else on the tractor once the engine is running. If the alternator fails and battery power is not reaching the after fire solenoid through the key switch, it will not work.

This is an unusual set of circumstances.

In the REVERSE CAUTION MODE (yellow zone), the same characteristics are true as for the normal run position, but in addition the L ter- minal will have continuity with the A2 terminal.

The A2 terminal is connected to the RMC mod- ule by a purple wire (electric PTO) or a white

wire (manual PTO). The L terminal (formerly

used for the lighting circuit) connects directly to the ground circuit of green wires. When the key is in the REVERSE CAUTION MODE position, the purple wire carries a ground signal to the RMC module. When the parking brake is not set, this ground signal arms (enables), but does not

tum-on the RMC module. Symptom-RMC module will not turn-on: Check

for continuity between A2 and L terminals on the

key switch when it is in the REVERSE CAUTION MODE position. Confirm that the green wire has continuity to ground. If the switch is capable of establishing a ground signal to the RMC module, the problem is likely to lie elsewhere in the sys-

tem. Symptom-RMC module will not turn-on: confirm

that the ground path (continuity to ground) to the purple or white wire is broken when the key switch is in any position other than REVERSE

CAUTION MODE. The RMC module is disarmed (disabled) when the parking brake is set. To re-

arm the module, the key is moved to another position, breaking the ground signal, then

returned to the REVERSE CAUTION MODE, re- establishing the ground signal. It works some-

thing like a latched relay. If it is not possible to break the ground-path, it is not possible to

freshly establish it either, and the RMC module will not be armable. Causes for such a condition

might include a shorted or incorrect key switch, or a chafed purple wire shorting to ground between the key switch and the RMC module.

RMC module

The RMC Module is in the same housing as the key switch, and is not available separately. For the purpose of diagnosis it is treated separately. Diagnosis of the module with the key switch introduces too many over- lapping variables. See Figure 7.3.

RMC Module

Key Switch

Figure 7.3

Principle: To diagnose the module, the simplest

approach is to check all of the inputs (safety cir- cuits) that are connected to it. If the inputs work properly, but the RMC module does not work properly (outputs), then the module can be determined to be faulty. A specific procedure is covered, following the description of the correct operation of the RMC module.

Working properly: The module cannot be diag-

nosed if it's function is not understood. It is designed to work as follows: See Figure 7.4.

When the RMC module is disarmed, the tractor

will operate as MTD tractors have historical

operated:

If reverse is engaged when the electric PTO is

ON, the PTO clutch will turn-off. On tractors with a manual PTO the engine will turn off.

If the operator leaves the seat with the engine

running, the engine will turn off.

If the operator leaves the seat with the PTO in the OFF position, the engine will turn-off unless the brake is applied.

When the RMC module is armed, the tractor will operate identically to when the module is dis-

armed.

CRAFTSMAN

When the RMC module is armed and turned- on: The tractor will operate identically to when

the module is disarmed, except that the operator will be able to put the transmission in reverse with the PTO engaged and the cutting deck will

continue to run The operator may put the tractor

into and out of reverse as many times as they wish without having to re-arm or turn-on the

module again.

To arm the RMC module: the operator must

turn the key switch to the REVERSE CAUTION

MODE (yellow zone), with the parking brake

released. See Figure 7.4.

Figure 7.4

To re-arm and turn the module ON: If the key is in REVERSE CAUTION MODE

position, it must be turned to another position (Normal Run), then returned to REVERSE CAU-

TION MODE. Once re-armed, the module can be turned-on by pressing orange triangular but-

ton. It will be confirmed that the module is ON by the illumination of the red LED on the module.

To identify a faulty RMC module: If the RMC module does not function as described, the RMC

plug test should be the first step in diagnosis. If the RMC plug test confirms that the safety cir-

cuits (inputs) work as designed, yet the RMC module does not work properly, the RMC mod- ule is faulty.

The RMC plug test will give an indication of what

the problem is if it is not a faulty RMC module. If the problem is identified in a particular circuit, check the safety switch that is associated with that circuit. If the switch is good, then the prob- lem lies within the wiring harness.

NOTE: Like the electronic components found on most cars, the RMC module requires a fully charged battery to work properly. If the system voltage falls below 12 V. an accurate diagnosis of the RMC module is impossible because the module will be temporarily disabled by low volt- age.

To turn the RMC module ON: The module must first be armed, then the orange triangular button

is depressed, illuminating the red LED indicator

to indicate that it is ON. It is important that the

operator must take two actions to turn the RMC

module ON so that they do not do so inadvert-

ently. See Figure 7.4.

The RMC module will turn-OFF and disarm if:

• The operator moves the key to any posi- tion other than REVERSE CAUTION

MODE.

The operator sets the parking brake.

If the operator leaves the seat without setting the parking brake, the engine will turn-off. The key movement necessary to

re-start the engine will make it necessary to re-arm and turn-on the RMC module if

the operator wishes to continue with the ability put the tractor in reverse while the

PTO is running.

ELECTRICAL SYSTEM

RMC module plug test (electric PTO)

1. Disconnect the molded 8-pin plug from the RMC module. See Figure 7.5.

Looking at the plug head-on, it will be configured as shown in the diagram: There will be 8 female pin terminals. When probed they should yield the results described in the following sections. See Figure 7.6.

Empty

Figure 7.6

Top left middle square-shape: Yellow wire with Black trace:

Behavior: Should show DC power with the key

on.

Circuitry: The yellow wire with black leads to the PTO switch and the PTO relay. It allow the RMC module to apply a ground to the coil of the PTO relay, which energizes the relay, severing the ground to the PTO clutch. When the PTO relay energizes it also applies a ground to the PTO switch. This ground loops back to the PTO relay's coil, latching it in the energized position.

Interpretation: If behavior is correct, the N.C. side of the PTO switch/circuit is functioning properly

If there is continuity to ground, then there is a

short to ground either between the PTO relay and the RMC module or in the PTO switch circuit.

Bottom left middle rounded-shape: Yellow wire

Behavior: When the terminal is probed (yellow wire), there should be continuity to ground only when the seat is empty.

Circuitry: The yellow wire leads to the seat

safety switch, where it finds a path to ground when the seat is empty.

Interpretation: If behavior is correct, the seat

safety circuit is good. If there is continuity to

ground when the seat is occupied, the switch

may be inoperative, or there may be a short to

ground in the wire leading to it. If there is not

continuity to ground when the seat is empty, the

switch may be inoperative or there may be an

open condition in the wire leading to it.

Top right middle square-shape: There is a red wire with black trace between yellow wire with a

black trace and the green wire. This wire pro-

vides the module with input from the reverse

switch.

Behavior: When the tractor is in reverse, this

terminal should have continuity to ground.

Circuitry: This wire runs directly to the reverse

safety switch.

Interpretation: Continuity to ground when the

tractor is not in reverse would indicate a short to

ground. This could take the form of a chafed wire

contacting ground or a shorted reverse safety

switch.

CRAFTSMAN

Lack of continuity to ground would indicate:

• A broken or disconnected wire leading to the reverse safety switch

• A switch that is not closing because of physical damage or corrosion.

• Loss of ground to the reverse switch.

Top right rounded-shape: is a qreen wire. Behavior: The green wire should always have

continuity to ground.

Circuitry: The green wire leads to ground. Interpretation: If this ground path is not good,

there will probably be other ground-related issues with the tractor: slow starter motor, slow

battery charge, dim lights. All ground connec- tions should be mechanically secure and corro-

sion free.

Bottom left square-shape: The red wire on the OCR plug carries battery voltage.

Behavior: With key switch in any of the run posi- tions, D.C. battery voltage should show-up on a volt meter when the red probe is touched to this terminal and the black probe is grounded.

Interpretation: If the purple wire fails to reach a ground path when the key switch is in the REVERSE CAUTION MODE position, the RMC module will not arm or operate. Check the key switch for continuity between A2 and L in the REVERSE CAUTION MODE position, confirm that the green wire connecting to the L terminal does have good continuity to ground, and check

for any loss of continuity in the purple wire that

extends from the key switch to the RMC module, including the molded connector between the two components.

If the RMC plug test indicates fault with any of the safety switches, the next step is to test the suspect switch. The operation of those switches is described in the following sections.

Circuitry: This wire draws power from the A1 terminal on the key switch.

Interpretation: If there is not battery voltage at this terminal, the tractor is probably not function at all. Look for a blown fuse or a bad key switch.

Bottom right middle rounded-shape: The DurDle

wire provides a ground signal to the RMC mod-

ule when the key switch is placed in the

REVERSE CAUTION MODE. Behavior: There should be continuity to ground

at this terminal when the key switch is in the REVERSE CAUTION MODE position.

Circuitry: When the key switch is in the REVERSE CAUTION MODE position, a ground path is established by connecting terminal A2 to

terminal L within the key switch. The purple wire from the RMC module connects to A2, and a

green ground wire connects to L.

ELECTRICALSYSTEM

RMCmoduleplugtest(manualPTO)

1. Disconnect the molded 8-pin plug from the RMC module. See Figure 7.7.

Looking at the plug head-on, itwill be configured as shown in the diagram: There will be 8 female pin terminals. When probed they should yield the results described in the following sections. See Figure 7.8.

Empty

Top left rounded-shape: Yellow wire Behavior: When the terminal is probed (yellow

wire), there should be continuity to ground when

the seat is empty. Circuitry: The yellow wire leads to the seat

safety switch, where it finds a path to ground

when the seat is empty.

NOTE: The yellow wire also branches off to the PTO switch. If the PTO is "on" and the key switch is turned to the "off" position, the yellow

wire will get a ground through the key switch.

Interpretation: If behavior is correct, the seat safety circuit is good. If there is continuity to ground when the seat is occupied, the switch may be inoperative, the PTO is on while the key switch is off or there may be a short to ground in the wire leading to it. If there is not continuity to ground when the seat is empty, the switch may be inoperative or there may be an open condi- tion in the wire leading to it.

Top right middle square-shape: There is a red

wire with black trace between yellow wire and

the green wire. This wire provides the module

with input from the reverse switch.

Behavior: When the tractor is in reverse, this terminal should have continuity to ground.

Circuitry: This wire runs directly to the reverse safety switch.

Figure 7.8

Interpretation: Continuity to ground when the

tractor is not in reverse would indicate a short to ground. This could take the form of a chafed wire

contacting ground or a shorted reverse safety switch.

Lack of continuity to ground would indicate:

• A broken or disconnected wire leading to the reverse safety switch

• A switch that is not closing because of physical damage or corrosion.

• Loss of ground to the reverse switch.

Top right rounded-shape and the bottom right square shape: are qreen wires.

Behavior: The green wires should always have continuity to ground.

Circuitry: The green wires leads to ground.

CRAFTSMAN

Interpretation: If this ground path is not good, there will probably be other ground-related

issues with the tractor: slow starter motor, slow battery charge, dim lights. All ground connec-

tions should be mechanically secure and corro- sion free.

Bottom left square-shape: The red wire on the OCR plug carries battery voltage.

Behavior: With key switch in any of the run posi- tions, D.C. battery voltage should show-up on a volt meter when the red probe is touched to this terminal and the black probe is grounded.

Circuitry: This wire draws power from the A1 terminal on the key switch.

Interpretation: If there is not battery voltage at this terminal, the tractor is probably not func- tional at all. Look for a blown fuse or a bad key

switch.

Bottom left middle square-shape: There is a black wire with a white trace between the red

wire and the white wire. This wire provides the

module with input from the park brake switch.

Circuitry: When the key switch is in the REVERSE CAUTION MODE position, a ground path is established by connecting terminal A2 to terminal L within the key switch. The white wire

from the RMC module connects to A2, and a

green ground wire connects to L. Interpretation: If the white wire fails to reach a

ground path when the key switch is in the REVERSE CAUTION MODE position, the RMC module will not arm or operate. Check the key switch for continuity between A2 and L in the REVERSE CAUTION MODE position, confirm that the green wire connecting to the L terminal does have good continuity to ground, and check

for any loss of continuity in the white wire that

extends from the key switch to the RMC module, including the molded connector between the two components.

If the RMC plug test indicates fault with any of the safety switches, the next step is to test the suspect switch. The operation of those switches is described in the following sections.

Behavior: When the brake pedal is depressed and the park brake is set, a ground path is estab- lished through the black wire with a white trace..

Circuitry: This wire runs to the brake switch,

then on to the park brake switch..

Interpretation: Continuity to ground when the park brake is not set would indicate a short to

ground. This could take the form of a chafed wire

contacting ground or a shorted reverse safety switch.

Lack of continuity to ground would indicate:

• A broken or disconnected wire leading to the brake or park brake switches

• A switch that is not closing because of physical damage or corrosion.

• Loss of ground to the park brake switch.

Bottom right middle rounded-shape: The white

wire provides a ground signal to the RMC mod-

ule when the key switch is placed in the

REVERSE CAUTION MODE.

Behavior: There should be continuity to ground at this terminal when the key switch is in the REVERSE CAUTION MODE position.

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Craftsman 28984, 28980, 28906, 28981 User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual