Maxon DMD-22, DMD-33 Maintenance Manual

M-16-40
AUGUST 2018

© MAXON Lift Corp. 2018

11921 Slauson Ave.
Santa Fe Springs, CA. 90670

LIFT CORP.

CUSTOMER SERVICE:

TELEPHONE [phone] TOLL FREE [phone]

FAX: [phone]

NOTE: For latest version of all Manuals (and replacements), download the

Manuals from Maxon’s website at www.maxonlift.com.

WARRANTY/ RMA POLICY & PROCEDURE

LIFTGATE WARRANTY

Type of Warranty: Full Parts and Labor

Term of Warranty: Standard Liftgates - 2 years from ship date or 6,000 cycles
Premium Liftgates - 2 years from ship date or 10,000 cycles

This warranty shall not apply unless the product is installed, operated and maintained in accordance with MAXON Lift’s specifi cations as set forth in
MAXON Lift’s Installation, Operation and Maintenance manuals. This warranty does not cover normal wear, maintenance or adjustments, damage or
malfunction caused by improper handling, installation, abuse, misuse, negligence, or carelessness of operation. In addition, this warranty does not
cover equipment that has had unauthorized modifi cations or alterations made to the product.

MAXON agrees to replace any components which are found to be defective during the fi rst 2 years of service, and will reimburse for labor based on
MAXON’s Liftgate Warranty Flat Rate Schedule. (Copy of the Flat Rate is available at www.maxonlift.com.)

All warranty repairs must be performed by an authorized MAXON warranty facility. For any repairs that may exceed $500, including parts and labor,
MAXON’s Technical Service Department must be notifi ed and an “Authorization Number” obtained.

All claims for warranty must be received within 30 Days of the repair date, and include the following information:

1. Liftgate Model Number and Serial Number

2. The End User must be referenced on the claim

3. Detailed Description of Problem

4. Corrective Action Taken, and Date of Repair

5. Parts used for Repair, Including MAXON Part Number(s)

6. MAXON R.M.A. # and/or Authorization # if applicable (see below)

7. Person contacted at MAXON if applicable

8. Claim must show detailed information i.e. Labor rate and hours of work performed

Warranty claims can also be placed online at www.maxonlift.com. Online claims will be given priority processing.

All claims for warranty will be denied if paperwork has not been received or claim submitted via Maxon website for processing by MAXON’s Warranty
Department within 30 days of repair date.

All components may be subject to return for inspection, prior to the claim being processed. MAXON products may not be returned without prior written
approval from MAXON’s Technical Service Department. Returns must be accompanied by a copy of the original invoice or reference with original
invoice number and are subject to a credit deduction to cover handling charges and any necessary reconditioning costs. Unauthorized returns will be

refused and will become the responsibility of the returnee.

Any goods being returned to MAXON Lift must be pre-approved for return, and have the R.M.A. number written on the outside of the package in plain
view, and returned freight prepaid. All returns are subject to a 15% handling charge if not accompanied by a detailed packing list. Returned parts
are subject to no credit and returned back to the customer. Defective parts requested for return must be returned within 30 days of the claim date for
consideration to:

10321 Greenleaf Ave., Santa Fe Springs, CA 90670

MAXON’s warranty policy does not include the reimbursement for travel time, towing, vehicle rental, service calls, oil, batteries or loss of income due to
downtime. Fabrication or use of non Maxon parts, which are available from MAXON, are also not covered.

MAXON’s Flat Rate Labor Schedule takes into consideration the time required for diagnosis of a problem.

All Liftgates returned are subject to inspection and a 15% restocking fee. Any returned Liftgates or components that have been installed or not returned
in new condition will be subject to an additional reworking charge, which will be based upon the labor and material cost required to return the Liftgate or
component to new condition.

PURCHASE PART WARRANTY

Term of Warranty: 1 Year from Date of Purchase.

Type of Warranty: Part replacement only. MAXON will guarantee all returned genuine MAXON replacement parts upon receipt and inspection of parts
and original invoice.
All warranty replacements parts will be sent out via ground freight. If a rush shipment is requested, all freight charges will be billed to the requesting
party.

MAXON Lift Corp.

Attn: RMA#__

TABLE OF CONTENTS

WARNINGS ........................................................................................................................... 6

SAFETY INSTRUCTIONS .................................................................................................... 7

LIFTGATE TERMINOLOGY .................................................................................................. 8

PERIODIC MAINTENANCE .................................................................................................. 9

PERIODIC MAINTENANCE CHECKS .................................................................................. 9

PREVENTATIVE MAINTENANCE (PM) CHECKLIST ......................................................... 10

CHECKING HYDRAULIC FLUID .........................................................................................11

CHANGING HYDRAULIC FLUID ........................................................................................ 13

PRESSURIZING HYDRAULIC SYSTEM ............................................................................ 15

TORSION BAR REPLACEMENT & ADJUSTMENT............................................................ 16

DECALS .............................................................................................................................. 26

SYSTEM DIAGRAMS ......................................................................................................... 28

PUMP MOTOR & VALVE OPERATION (MANUAL CLOSE) ............................................... 28

PUMP MOTOR & VALVE OPERATION (EQUIPPED WITH HYDRAULIC CLOSER) ......... 29

HYDRAULIC SCHEMATIC (MANUAL CLOSE) .................................................................. 30

HYDRAULIC SCHEMATIC (EQUIPPED WITH HYDRAULIC CLOSER) ............................ 31

ELECTRICAL SCHEMATIC (MANUAL CLOSE) ................................................................ 32

ELECTRICAL SCHEMATIC (EQUIPPED WITH HYDRAULIC CLOSER) ........................... 33

ELECTRICAL SCHEMATIC - JUMPER HARNESS ASSEMBLY ........................................ 34

ELECTRICAL SCHEMATIC - HOUSING COVER ASSEMBLY (WITHOUT LIGHTS) ......... 35

ELECTRICAL SCHEMATIC - HOUSING COVER ASSEMBLY (WITH FOUR LIGHTS) .... 36

ELECTRICAL SCHEMATIC - HOUSING COVER ASSEMBLY, FOREIGN VEHICLE

(WITH 6 LIGHTS ) ...............................................................................................................37

DMD ELECTRICAL VALUES .............................................................................................. 38

RECOMMENDED BOLT TORQUES .................................................................................. 39

THIS PAGE INTENTIONALLY LEFT BLANK

Comply with the following WARNINGS and SAFETY INSTRUCTIONS while maintaining
Liftgates. See Operation Manual for operating safety requirements.

!

WARNINGS

• Do not stand, or allow obstructions, under the platform when lowering the Liftgate. Be sure your

feet are clear of the Liftgate.

• Keep fi ngers, hands, arms, legs, and feet clear of moving Liftgate parts (and platform
edges) when operating the Liftgate.

• Correctly stow platform when not in use. Extended platforms could create a hazard for

11921 Slauson Ave. Santa Fe Springs, CA. 90670 [phone] FAX [phone]

people and vehicles passing by.

• Disconnect Liftgate power cable from battery before repairing or servicing Liftgate.

• If it is necessary to stand on the platform while maintaining the Liftgate, keep your feet and any

objects clear of the inboard edge of the platform. Your feet or objects on the platform can become
trapped between the platform and the Liftgate housing cover.

• Recommended practices for welding on steel parts are contained in the current AWS (American
Welding Society) D1.1 Structural Welding Code - Steel. Damage to Liftgate and/or vehicle, and

personal injury could result from welds that are done incorrectly.

• Recommended practices for welding on aluminum parts are contained in the current AWS
(American Welding Society) D1.2 Structural Welding Code - Aluminum. Damage to Liftgate

and/or vehicle, and personal injury could result from welds that are done incorrectly.

WARNING

6

SAFETY INSTRUCTIONS

• Read and understand the instructions in this Maintenance Manual before performing mainte-

nance on the Liftgate.

• Before operating the Liftgate, read and understand the operating instructions in Operation
Manual.

• Comply with all WARNING and instruction decals attached to the Liftgate.

• Keep decals clean and legible. If decals are illegible or missing, replace them. Free replacement
decals are available from Maxon Customer Service.

• Consider the safety and location of bystanders and location of nearby objects when operating the

Liftgate. Stand to one side of the platform while operating the Liftgate.

• Do not allow untrained persons to operate the Liftgate.

• Wear appropriate safety equipment such as protective eyeglasses, faceshield and clothing while

performing maintenance on the Liftgate and handling the battery. Debris from drilling and contact
with battery acid may injure unprotected eyes and skin.

• Be careful working by an automotive type battery. Make sure the work area is well ventilated and
there are no fl ames or sparks near the battery. Never lay objects on the battery that can short the
terminals together. If battery acid gets in your eyes, immediately seek fi rst aid. If acid gets on your
skin, immediately wash it off with soap and water.

SAFETY INSTRUCTIONS

• If an emergency situation arises (vehicle or Liftgate) while operating the Liftgate, release the con-

trol switch to stop the Liftgate.

• A correctly installed Liftgate operates smoothly and reasonably quiet. The only noticeable noise
during operation comes from the power unit while the platform is raised. Listen for scraping, grat­ing and binding noises and correct the problem before continuing to operate Liftgate.

• Use only Maxon Authorized Parts for replacement parts. Provide Liftgate model and serial num­ber information with your parts order. Order replacement parts from:

MAXON LIFT CORP. Customer Service

11921 Slauson Ave., Santa Fe Springs, CA 90670

Online: www.maxonlift.com
Express Parts Ordering: Phone [phone] ext. 4345
Email: Ask your Customer Service representative

11921 Slauson Ave. Santa Fe Springs, CA. 90670 [phone] FAX [phone]

7

LIFTGATE TERMINOLOGY

11921 Slauson Ave. Santa Fe Springs, CA. 90670 [phone] FAX [phone]

(BEHIND COVER)

COLUMN

POWER UNIT

RUNNER

UP/DOWN

CONTROL SWITCH

(INBOARD)

MAIN FRAME

TRANSIT

HOOK

PLATFORM

LATCH

UP/DOWN

CONTROL SWITCH

(OUTBOARD)

HOUSING

COVER

PLATFORM

FOLD/UNFOLD SWITCH

(IF EQUIPPED WITH

HYDRAULIC CLOSER)

8

PERIODIC MAINTENANCE

PERIODIC MAINTENANCE CHECKS

!

WARNING

Never operate the Liftgate with parts loose or missing.

NOTE: Photocopy the PM CHECKLIST on the next page to help keep track of periodic

maintenance on the Liftgate. Keep completed form with maintenance records.

Annually

Visually check the entire Liftgate for excessively worn parts and broken welds, especially
the hinge pins. See Parts Manual for replacement parts. Also, do the Semi-annual and

Quarterly Maintenance checks.

Semi-annually

Visually check the platform hinge pins for excessive wear and broken welds. See Parts
Manual for replacement parts. Also, do the Quarterly Maintenance checks.

Quarterly

Check the hydraulic fl uid level in the pump reservoir. Refer to the CHECKING HYDRAULIC
FLUID procedure in the PERIODIC MAINTENANCE section.

If hydraulic fl uid appears contaminated, refer to the CHANGING HYDRAULIC FLUID

procedure on following page.

Keep track of the grade of hydraulic fl uid in the pump reservoir. Never mix two different

grades of fl uid.

Check lines and fi ttings for chaffi ng and fl uid leaks. Replace if necessary.

Check electrical wiring for chaffi ng and make sure wiring connections are tight and free

of corrosion.

Check that all WARNING and instruction decals are in place and legible.

Check for loose or missing nuts, bolts, covers, roll pins, screws and pins.

Check that platform latch and transit hook mechanisms work correctly and no parts are

missing.

CAUTION

Damaged cylinder seals and contaminated hydraulic fl uid can result from paint-
ing the polished portion of the cylinder rod. To prevent damage, protect the
exposed polished portion of the cylinder rod while painting.

11921 Slauson Ave. Santa Fe Springs, CA. 90670 [phone] FAX [phone]

Check for rust and oily surfaces on Liftgate. If there is rust or oil on the Liftgate, clean it

off. Touch up the paint where bare metal is showing.

9

PM Interval: 3 Months Date: / /

Equipment: W/O # Location:

Mechanic: Serial # Model #

11921 Slauson Ave. Santa Fe Springs, CA. 90670 [phone] FAX [phone]

Check Appropriate Box. “

Satisfactory

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





















Satisfactory

Satisfactory

Satisfactory

Satisfactory

Satisfactory

Satisfactory

Satisfactory

Satisfactory

Satisfactory

Satisfactory

Satisfactory

Satisfactory

Satisfactory

Satisfactory

Satisfactory

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PERIODIC MAINTENANCE

PREVENTATIVE MAINTENANCE (PM) CHECKLIST

”

MAXON 1

Repair Required

Repair Required

Repair Required

Repair Required

Repair Required

Repair Required

Repair Required

Repair Required

Repair Required

Repair Required

Repair Required

Repair Required

Repair Required

Repair Required

Repair Required

Repair Required

st

, 2nd and 3rd Quarter Liftgate Preventative Maintenance (PM) Procedures

Verify if the Quarterly or Annual PM is due by checking the PM sticker on

1

the curbside Liftgate column.
2 Check for oil leaks at: cylinders, valves, and fi ttings.
3 Check for damage: platform, column, runners and hydraulic tubes.
4 Check for loose or missing nuts, bolts, covers, roll pins, screws and pins.

Check for cracked welds at: columns, runners, platform, main housing
5

and vehicle door frame.

Check platform lowering speed: Range is 16 - 30 seconds. Check
6

cylinder lock valves for proper operation.
7 Check platform pins and couplers.

8 Check platform raising speed: Range is 12-13 seconds.

Check that platform unlatches, unfolds & folds smoothly & latches
9

securely.

Check switches and wiring connections on Liftgate as well as pump

10

inside main housing. Also check ground straps.

Check the gear pump for unusual noise, i.e. squealing or extreme RPM

11

output.

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Corrected

Corrected

Corrected

Corrected

Corrected

Corrected

Corrected

Corrected

Corrected

Corrected

Corrected

Checking Oil Level: gravity down with the platform unfolded and on the

ground. Oil level should be as shown in Installation Manual, “CHECKING

12

HYDRAULIC FLUID”. Check for contamination, change if needed.

13 Check batteries: load test, corrosion, cables, hold downs and water level.
14 Check all charging and ground cable connections.






Corrected

Corrected

Corrected

Complete a new PM sticker and install it on the curbside column of the

Liftgate. The next PM date is 3 months from the completed PM date.

15

Indicate on the PM sticker if 1st, 2nd, 3rd or 4th PM.

Check that platform latch and transit hook mechanisms work correctly

16

and no parts are missing.





Corrected

Corrected

th

Quarter Liftgate Preventative Maintenance (PM). Note: Includes steps 1-16

Corrected



Corrected






Satisfactory

Satisfactory

MAXON 4

Repair Required



Repair Required



For more detailed information, please refer to the product maintenance manuals. Use only genuine Maxon replacement
parts for all repairs.

17 Change hydraulic fl uid.
18 Inspect wear on slide pads.

TABLE 10-1

10

PERIODIC MAINTENANCE

CHECKING HYDRAULIC FLUID

CAUTION

Keep dirt, water and other contaminants from entering the hydraulic system.
Before opening the hydraulic fl uid reservoir fi ller cap, drain plug and hydraulic
lines, clean up contaminants that can get in the openings. Also, protect the
openings from accidental contamination.
Never mix synthetic fl uids with conventional hydraulic fl uids. Hydraulic system
must be purged if the fl uids are mixed.

NOTE: Liftgate is shipped with Exxon Univis HVI-13 hydraulic fl uid in the hydraulic

cylinders. Exxon Univis HVI-13 hydraulic fl uid is recommended for operating
temperatures of -40 to +120° F. Refer to decal in pump box. Under certain
conditions, other brands and grades of oil may be used as substitutes for the
recommended oil. Refer to TABLES 12-1 & 12-2.

NOTE: If the hydraulic fl uid in the reservoir is contaminated, do the CHANGING
HYDRAULIC FLUID procedure in this section.

1. Open and lower platform to the
ground (FIG. 11-1). Refer to
Operation Manual for detailed
operating instructions.

2. Unbolt main housing cover
as shown in FIG. 11-1.
Remove cover.

BOLT,

LOCK WASHER &

FLAT WASHER

(3 PLACES)

3. Check the hydraulic fl uid level in
reservoir as follows. With platform
on the ground, level should be as
shown in FIG. 11-2.

4. If needed, add fl uid to the reservoir as

follows. Remove fi ller cap (FIG. 11-2).
Fill the reservoir with hydraulic fl uid to
level shown in FIG. 11-2. Reinstall fi ller
cap.

CAUTION

Main housing cover must be
correctly secured to prevent it
from becoming a hazard.

5. Bolt on the main housing cover

as shown in FIG. 11-1. Torque
the 5/16”-18 cover bolts from 10

to 14 lb-ft.

COVER

UNBOLTING/ BOLTING COVER
(PLATFORM ON THE GROUND)

FIG. 11-1

POWER UNIT

3-3/4” MAX

3-1/4” MIN

RESERVOIR

POWER UNIT FLUID LEVEL

FILLER CAP

(MANUAL CLOSE POWER UNIT SHOWN)

FIG. 11-2

11

11921 Slauson Ave. Santa Fe Springs, CA. 90670 [phone] FAX [phone]

(REF)

ISO 32 HYDRAULIC OIL

11921 Slauson Ave. Santa Fe Springs, CA. 90670 [phone] FAX [phone]

RECOMMENDED

BRANDS

CHEVRON HIPERSYN 32

KENDALL GOLDEN MV

SHELL TELLUS S2 VX 32

EXXONMOBIL UNIVIS N-32, DTE-24

PART NUMBER

TABLE 12-1

ISO 15 OR MIL-H-5606 HYDRAULIC OIL

RECOMMENDED

BRANDS

CHEVRON FLUID A, AW-MV-15

KENDALL GLACIAL BLU

SHELL TELLUS S2 VX 15

EXXONMOBIL UNIVIS HVI-13

ROSEMEAD THS FLUID 17111

PART NUMBER

TABLE 12-2

12

PERIODIC MAINTENANCE

CHANGING HYDRAULIC FLUID

CAUTION

Keep dirt, water and other contaminants from entering the hydraulic system.
Before opening the hydraulic fl uid reservoir fi ller cap, drain plug and hydraulic
lines, clean up contaminants that can get in the openings. Also, protect the
openings from accidental contamination.
Never mix synthetic fl uids with conventional hydraulic fl uids. Hydraulic system
must be purged if the fl uids are mixed.

NOTE: Liftgate is shipped with Exxon Univis HVI-13 hydraulic fl uid in the hydraulic

cylinders. Exxon Univis HVI-13 hydraulic fl uid is recommended for operating
temperatures of -40 to +120° F. Refer to decal in pump box. Under certain
conditions, other brands and grades of oil may be used as substitutes for the
recommended oil. Refer to TABLES 12-1 & 12-2.

1. Open and lower platform to the

ground (FIG. 13-1). Refer to
Operation Manual for detailed
operating instructions.

BOLT,

LOCK WASHER &

FLAT WASHER

(3 PLACES)

2. Unbolt main housing cover

as shown in FIG. 13-1.
Remove cover.

3. Remove drain plug (FIG. 13-2).

Then, drain hydraulic fl uid from
reservoir.

4. Reinstall drain plug (FIG. 13-2).

Then, add new Univis HVI-13
hydraulic fl uid to level shown in
FIG. 13-2.

5. Remove fi ller cap (FIG. 13-2).

Then, add new Univis HVI-13
hydraulic fl uid to level shown in

FIG. 13-2. Reinstall fi ller cap.

COVER

UNBOLTING COVER

(PLATFORM ON THE GROUND)

FIG. 13-1

POWER UNIT

(REF)

3-3/4” MAX

3-1/4” MIN

RESERVOIR

DRAIN PLUG

POWER UNIT FLUID LEVEL

FILLER CAP

(MANUAL CLOSE POWER UNIT SHOWN)

FIG. 13-2

11921 Slauson Ave. Santa Fe Springs, CA. 90670 [phone] FAX [phone]

13

6. Raise platform to bed height (FIG. 14-1).
Continue to hold UP/DOWN control
switch for 30 - 60 seconds to circulate
hydraulic fl uid through slave cylinder
and reservoir (FIG. 14-2). Release UP/
DOWN control switch.

11921 Slauson Ave. Santa Fe Springs, CA. 90670 [phone] FAX [phone]

NOTE: Three cycles of draining, fi lling,

and circulating hydraulic fl uid
should be enough to fi ll the sys-
tem with new hydraulic fl uid.

UP/DOWN
CONTROL

SWITCH

PLATFORM AT BED HEIGHT

FIG. 14-1

7. Repeat instructions 1 through 5,
two times. Keep the platform open
and cover removed.

8. Lower platform to the
ground (FIG. 14-3).

CAUTION

Main housing cover must be
correctly secured to prevent it
from becoming a hazard.

POWER UNIT

(REF)

RESERVOIR

POWER UNIT

(MANUAL CLOSE POWER UNIT SHOWN)

FIG. 14-2

BOLT,

LOCK WASHER &

FLAT WASHER

(3 PLACES)

COVER

9. Bolt on the main housing cover
as shown in FIG. 14-3. Torque
the 5/16”-18 cover bolts from
10 to 14 lb-ft.

14

BOLTING ON COVER

FIG. 14-3

PERIODIC MAINTENANCE

PRESSURIZING HYDRAULIC SYSTEM

!

CAUTION

Operating Liftgate, under certain conditions, with air in system could result in
damage to lift and load as well as personal injury. If lines are opened & closed
or replaced, and if power unit or cylinders are replaced, pressurize hydraulic
system before operating Liftgate with a passenger or load.

NOTE: When pump pressurizes fl uid in hydraulic system, air is bled into reservoir

through slave cylinder return line.

To pressurize lifting cylinders,
hold outboard control switch in
UP position for 30 - 60 sec­onds (FIG. 15-1). Then, re­lease toggle switch.

CONTROL SWITCH

FIG. 15-1

OUTBOARD

(UP)

11921 Slauson Ave. Santa Fe Springs, CA. 90670 [phone] FAX [phone]

15

REPLACE LH TORSION BAR

Ensure platform is latched securely in stowed
position to release most tension from torsion
bar(s) and keep platform from suddenly un­folding. Injury could result from unbolting the

11921 Slauson Ave. Santa Fe Springs, CA. 90670 [phone] FAX [phone]

torsion bar(s) under tension. When all tension
is released from torsion bar(s), platform can
unfold suddenly. Any person in the path of
opening platform could be injured.

TORSION BAR REPLACEMENT & ADJUSTMENT

!

WARNING

PLATFORM

1. Stow platform (FIG. 16-1). Ensure
platform is latched securely. Refer
to Operation Manual for detailed
operating instructions.

2. Support platform and fl ipover evenly
by placing supports under the RH
and LH runners (FIG. 16-1).

3. Remove cap screw and washers from
torsion bar pin (FIG. 16-2). Initial torsion
bar tension is removed when torsion bar
pin is in position shown in FIG. 16-2A.

FLAT WASHER

(2 PLACES)

LOCK WASHER

CAP SCREW,

1/2”

TORSION

BAR PIN

LH RUNNER

SUPPORT

(2 PLACES)

RH RUNNER

FIG. 16-1

TORSION

BAR PIN

FIG. 16-2A

REMOVING INITIAL TENSION FROM LH TORSION BAR

FIG. 16-2

16

PERIODIC MAINTENANCE

TORSION BAR REPLACEMENT & ADJUSTMENT - Continued

4. With platform securely supported,
remove cover plate (FIG. 17-1).

5. Loosen locking screw from LH
torsion bar housing (FIG. 17-2).

PLATFORM

TAPPING
SCREWS

(8 PLACES)

COVER

PLATE

REMOVING COVER PLATE

FIG. 17-1

LH TORSION

BAR HOUSING

LH TORSION

BAR

LOCKING

SCREW

11921 Slauson Ave. Santa Fe Springs, CA. 90670 [phone] FAX [phone]

FIG. 17-2

17

TORSION BAR REPLACEMENT & ADJUSTMENT - Continued

6. Remove LH torsion bar pin (FIG. 18-1).

11921 Slauson Ave. Santa Fe Springs, CA. 90670 [phone] FAX [phone]

FLAT WASHER

(2 PLACES)

CAP SCREW,

1/2”

LOCK WASHER

TORSION BAR

PIN

REMOVING LH TORSION BAR PIN

FIG. 18-1

7. Remove LH torsion bar (FIG. 18-2).

LH TORSION

BAR

REMOVING LH TORSION BAR

FIG. 18-2

18

ADJUST LH TORSION BAR

WARNING

!

Platform can unfold suddenly with no tension on torsion bar. Stay out of the
path of unfolding platform when adjusting the torsion bar. Get second person
to help unlatch platform.

1. Stow platform. Refer to Operation
Manual for detailed operating

instructions.

TORSION

BAR PIN

2. On LH runner, remove cap screw, lock
washer and fl at washers from torsion bar pin
(FIG. 19-1). Adjust the LH torsion bar pin
counter-clockwise until tension is applied to
torsion bar (FIG. 19-1A). Replace cap screw,
lock washer and fl at washers (FIG. 19-1) and
tighten.

FIG. 19-1A

FLAT WASHER

(2 PLACES)

LOCK WASHER

CAP SCREW,

1/2”

TORSION

BAR PIN

11921 Slauson Ave. Santa Fe Springs, CA. 90670 [phone] FAX [phone]

INCREASING TENSION

FIG. 19-1

19

TORSION BAR REPLACEMENT & ADJUSTMENT - Continued

3. Unlatch platform (FIG. 20-1).
Platform should just escape the latch
as shown in FIG. 20-1, position 1.

4. Unfold platform until latch pin is 2”-3” from

latch (FIG. 20-1, position 2). Release
hold on platform. Observe If platform starts
to fold, stays partially unfolded, or starts

11921 Slauson Ave. Santa Fe Springs, CA. 90670 [phone] FAX [phone]

falling open with no restraint. Platform
should unfold slowly when released (FIG.
20-1, position 3). To increase the amount
of pull, adjust the torsion bar pin counter­ clockwise until increased tension is applied
to torsion bar (FIG. 19-1). Once the platform
is unfolded, it should lay fl at (FIG. 20-1,
position 3). If platform does not lay fl at,
decrease tension by removing cap screw,
lock washer and fl at washers from LH
torsion bar pin (FIG. 20-2). Adjust torsion
bar pin clockwise until tension is decreased
(FIG. 20-2A). Replace cap screw, lock
washer and fl at washers (FIG. 20-2)

and tighten.

3

FLAT WASHER

(2 PLACES)

CAP SCREW,

1/2”

2

1

FIG. 20-1

LOCK WASHER

TORSION

BAR PIN

5. If additional tension is needed,
stow platform (FIG. 20-3). Ensure
platform is latched securely. Refer
to Operation Manual for detailed
operating instructions.

6. Support platform and fl ipover evenly
by placing supports under the RH
and LH runners (FIG. 20-3).

FIG. 20-2A

LH RUNNER

SUPPORT

(2 PLACES)

20

TORSION

BAR PIN

DECREASING TENSION

FIG. 20-2

PLATFORM

RH RUNNER

FIG. 20-3

TORSION BAR REPLACEMENT & ADJUSTMENT - Continued

7. With platform securely supported,
remove cover plate (FIG. 21-1).

8. Loosen locking screw from LH

torsion bar housing (FIG. 21-2).

PLATFORM

TAPPING
SCREWS

(8 PLACES)

COVER

PLATE

REMOVING COVER PLATE

FIG. 21-1

LH TORSION

BAR HOUSING

LH TORSION

BAR

LOCKING

SCREW

11921 Slauson Ave. Santa Fe Springs, CA. 90670 [phone] FAX [phone]

FIG. 21-2

21

TORSION BAR REPLACEMENT & ADJUSTMENT - Continued

9. Increase LH torsion bar
tension by moving LH torsion
bar housing inboard towards
center of vehicle (FIG. 22-1).
Approximate adjustment
travel should be no more than
10”.

11921 Slauson Ave. Santa Fe Springs, CA. 90670 [phone] FAX [phone]

STOP BLOCK

0”- 10”

LH TORSION

BAR HOUSING

INCREASING LH TORSION BAR TENSION

FIG. 22-1

10. Replace and tighten LH
torsion bar housing locking
screw (FIG. 22-2).

LH TORSION

BAR

LOCKING

SCREW

11. Platform can be stowed or returned
to operation after adjustment is
done correctly.

LH TORSION

BAR HOUSING

FIG. 22-2

22

PERIODIC MAINTENANCE

TORSION BAR REPLACEMENT & ADJUSTMENT - Continued

REPLACE RH TORSION BAR (IF EQUIPPED)

1. Stow platform. Refer to Operation
Manual for detailed operating

instructions.

2. Support platform and fl ipover evenly
by placing supports under the RH
and LH runners (FIG. 23-1).

3. With platform securely supported,
remove cover plate (FIG. 23-2).

SUPPORT

(2 PLACES)

FIG. 23-1

PLATFORM

(8 PLACES)

REMOVING COVER PLATE

FIG. 23-2

TAPPING
SCREWS

COVER

PLATE

11921 Slauson Ave. Santa Fe Springs, CA. 90670 [phone] FAX [phone]

23

TORSION BAR REPLACEMENT & ADJUSTMENT - Continued

4. Loosen locking screw from RH
torsion bar housing (FIG. 24-1).

11921 Slauson Ave. Santa Fe Springs, CA. 90670 [phone] FAX [phone]

5. On RH runner, unbolt the platform and
runner pin from RH runner (FIG. 24-2). Next,
remove platform and runner pin, and platform
spacer (FIG. 24-2).

RH TORSION

BAR HOUSING

LOCKING

SCREW

RH TORSION

BAR

FIG. 24-1

PLATFORM &
RUNNER PIN

RH RUNNER

LOCK

WASHERS

6. Remove RH torsion bar (FIG.24-3).

PLATFORM

SPACER

RH TORSION

BAR

RH TORSION

BAR

CAP

SCREW

(2 PLACES)

FIG. 24-2

24

REMOVING RH TORSION BAR

FIG. 24-3

TORSION BAR REPLACEMENT & ADJUSTMENT - Continued

7. With platform in vertical
position, insert the torsion bar

into the RH platform and

runner pin, through RH
runner, platform spacer and
engage with RH torsion bar
housing (FIG. 25-1).

RH RUNNER

RH TORSION

BAR HOUSING

PLATFORM

SPACER

RH TORSION

BAR

PLATFORM &
RUNNER PIN

LOCK

WASHERS

CAP

SCREW

(2 PLACES)

8. Rotate the RH platform and
runner pin clockwise to line
up the pin holes with the RH
runner threaded holes (FIG.
25-2).

9. Secure RH platform and
runner pin as shown in FIG.
25-2.

10. Ensure platform is latched
securely in stow position. Then,
remove platform supports.

RH RUNNER

THREADED HOLES

FIG. 25-1

LOCK

WASHERS

(2 PLACES)

CAP

SCREW

(2 PLACES)

RH PIN

WELDMENT

FIG. 25-2

11921 Slauson Ave. Santa Fe Springs, CA. 90670 [phone] FAX [phone]

25

DECALS

NOTE: Decals are preinstalled at factory.

Decal location shown for reference.

NOTE: Ensure there is no residue, dirt or
corrosion where decals are attached.
If necessary, clean surface before
replacing decals.

11921 Slauson Ave. Santa Fe Springs, CA. 90670 [phone] FAX [phone]

DECAL “F” OR “G”

DMD-22 ONLY

CAPACITY DECAL

P/N 220388-03

DMD-33 ONLY

CAPACITY DECAL

P/N 220388-02

DECAL “E”

DECAL “D”

WARNING DECAL

P/N 298373-01

DECAL “B”

DECAL “A”

DECAL “C”

WARNING DECAL

P/N 299274-01

FAMILY OWNED DECAL

P/N 283445-01

COLUMN ARROW

DECAL “H”

P/N 289192-01

RUNNER ARROW

DECAL “H”

P/N 289192-01

26

DECAL SHEET
P/N 289192-01

11921 Slauson Ave. Santa Fe Springs, CA. 90670 [phone] FAX [phone]

WARNING DECAL

P/N 298373-01

WARNING DECAL

P/N 299274-01

27

PUMP MOTOR & VALVE OPERATION (MANUAL CLOSE)

11921 Slauson Ave. Santa Fe Springs, CA. 90670 [phone] FAX [phone]

SYSTEM DIAGRAMS

LOWERING

VALVE

STARTER

SWITCH

MOTOR

POWER UNIT

FIG. 28-1

POWER UNIT MOTOR & SOLENOID OPERATION

SOLENOID OPERATION

LIFTGATE
FUNCTION

RAISE -

LOWER -

REFER TO VALVES SHOWN ON

HYDRAULIC SCHEMATIC

( MEANS ENERGIZED)

MOTOR

STARTER

SWITCH

LOWERING

VALVE

TABLE 28-1

28

PUMP MOTOR & VALVE OPERATION

(EQUIPPED WITH HYDRAULIC CLOSER)

LOWERING

VALVE

POWER UNIT MOTOR & VALVE OPERATION

LIFTGATE
FUNCTION

STARTER

SWITCH

POWER UNIT

REMOTE VALVE OPERATION

MOTOR

MOTOR

FIG. 29-1

( MEANS ENERGIZED)

LOWERING

VALVE

FOLD/UNFOLD

FOLD/UNFOLD VALVE

ASSEMBLY

VALVE

RAISE

LOWER

UNFOLD

FOLD

11921 Slauson Ave. Santa Fe Springs, CA. 90670 [phone] FAX [phone]

REFER TO VALVES SHOWN ON

HYDRAULIC SCHEMATIC

TABLE 29-1

29

11921 Slauson Ave. Santa Fe Springs, CA. 90670 [phone] FAX [phone]

HYDRAULIC SCHEMATIC (MANUAL CLOSE)

3.0

FIG. 30-1

30

HYDRAULIC SCHEMATIC (EQUIPPED WITH HYDRAULIC CLOSER)

3.0

11921 Slauson Ave. Santa Fe Springs, CA. 90670 [phone] FAX [phone]

FIG. 31-1

31

11921 Slauson Ave. Santa Fe Springs, CA. 90670 [phone] FAX [phone]

ELECTRICAL SCHEMATIC (MANUAL CLOSE)

FIG. 32-1

32

ELECTRICAL SCHEMATIC (EQUIPPED WITH HYDRAULIC CLOSER)

11921 Slauson Ave. Santa Fe Springs, CA. 90670 [phone] FAX [phone]

FIG. 33-1

33

ELECTRICAL SCHEMATIC - JUMPER HARNESS ASSEMBLY

CONNECT TERMINALS TO

VEHICLE HARNESS

11921 Slauson Ave. Santa Fe Springs, CA. 90670 [phone] FAX [phone]

TERMINAL “A” GROUND

TERMINAL “B” TAIL

TERMINAL “C” REVERSE

ORANGE

BLACK

WHITE

GREEN

RED

YELLOW

TERMINAL “F” LH STOP/TURN

TERMINAL “E” RH STOP/TURN

TERMINAL “D” STOP

CONNECT MALE TERMINAL TO

COVER LIGHTS HARNESS

FOREIGN/DOMESTIC

FIG. 34-1

CONNECT TERMINALS TO

VEHICLE HARNESS

ORANGE

BLACK

WHITE

TERMINAL “A” GROUND

TERMINAL “B” TAIL

TERMINAL “C” REVERSE

CONNECT MALE TERMINAL TO

COVER LIGHTS HARNESS

ISUZU

FIG. 34-2

34

GREEN

RED

YELLOW

TERMINAL “F” LH STOP/TURN

TERMINAL “E” RH STOP/TURN

TERMINAL “D” STOP

SYSTEM DIAGRAMS

ELECTRICAL SCHEMATIC - HOUSING COVER ASSEMBLY

(WITHOUT LIGHTS)

CONNECT TO

WIRING HARNESS

LICENSE PLATE

LIGHT

LH LICENSE PLATE

LIGHT

RH LICENSE PLATE

LIGHT

11921 Slauson Ave. Santa Fe Springs, CA. 90670 [phone] FAX [phone]

FIG. 35-1

35

ELECTRICAL SCHEMATIC - HOUSING COVER ASSEMBLY

11921 Slauson Ave. Santa Fe Springs, CA. 90670 [phone] FAX [phone]

(WITH FOUR LIGHTS)

CONNECT TO

JUMPER HARNESS

36

CONNECT TO

VEHICLE HARNESS

SYSTEM DIAGRAMS

ELECTRICAL SCHEMATIC - HOUSING COVER ASSEMBLY,

FOREIGN VEHICLE (WITH 6 LIGHTS )

CONNECT TO

JUMPER HARNESS

37

CONNECT TO

VEHICLE HARNESS

11921 Slauson Ave. Santa Fe Springs, CA. 90670 [phone] FAX [phone]

SYSTEM DIAGRAMS

DMD ELECTRICAL VALUES

SOLENOID SWITCH 12V 24V

Coil Resistance:

Ampere:

Coil terminal torque: 10-15 lb-in max.

11921 Slauson Ave. Santa Fe Springs, CA. 90670 [phone] FAX [phone]

Contact terminal torque: 30-35 lb-in max.

Coil Resistance:

Ampere:

Coil terminal torque: 15-45 lb-in max.

Valve cartridge torque: 25-30 lb-ft max.

Coil nut torque: 15-45 lb-in

FOLD/UNFOLD VALVE

Coil Resistance:

Ampere:

5.4Ω @70ºF. ±15% 20.1Ω @70ºF. ±15%

2.2A 1.2A

LOWERING VALVE

6.6Ω @ 70ºF. ±15% 26.7Ω @ 70ºF. ±15%

1.8A 0.9A

8.0Ω @ 70ºF. ±15% 30Ω @ 70ºF. ±15%

1.5A 0.8A

Coil terminal torque: 3-4.5 lb-ft max.

Valve cartridge torque: 18.5-22 lb-ft max.

GROUND CABLE

Cap Screw Torque: 24 lb-ft max.

CYCLE COUNTER

Operation Voltage:

TABLE 38-1

7V - 30V 7V - 30V

38

RECOMMENDED BOLT TORQUES

CAUTION

The torque values in the following table are provided for torquing grade 8
bolts on Liftgate mechanical parts. To prevent damage, never use the infor­mation in this table for torquing electrical or hydraulic hose connections on
the pump assembly.

GRADE 8 BOLT TIGHTENING TORQUE

DIAMETER & THREAD PITCH TORQUE

1/4”-20 10-14 lb-ft

1/4”-28 11-16 lb-ft
5/16”-18 20-29 lb-ft
5/16”-24 22-33 lb-ft

3/8”-16 35-52 lb-ft

3/8”-24 40-59 lb-ft
7/16”-14 56-84 lb-ft
7/16”-20 62-93 lb-ft

1/2”-13 85-128 lb-ft

1/2”-20 96-144 lb-ft
9/16”-12 123-184 lb-ft
9/16”-18 137-206 lb-ft

5/8”-11 170-254 lb-ft

5/8”-18 192-288 lb-ft

3/4”-10 301-451 lb-ft

3/4”-18 336-504 lb-ft

TABLE 39-1

11921 Slauson Ave. Santa Fe Springs, CA. 90670 [phone] FAX [phone]

39