MAN Edc Troubleshooting Manual
Foreword
Dear Customer
These instructions are intended to help you properly carry out repairs on the electronically controlled diesel
injection system described in this document.
In writing these instructions, we have assumed that you have the necessary knowledge of control systems
for working on and with the electronic diesel control.
Best regards
MAN Nutzfahrzeuge Aktiengesellschaft
Nuremberg Plant
Since our products are in continuous development, we reserve the right to make technical modifications.
2002 MAN Nutzfahrzeuge Aktiengesellschaft
Reprint, duplication or translation, as a whole or in part without the written approval of MAN is prohibited.
MAN reserves all rights accorded by the relevant laws on copyright.
MTDA Technical status: 02.2002 51.99598–8049
1
Contents
Safety information 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electronic diesel control 6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
System description 7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Component description 9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Control unit plug connector 9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Injection pump 11 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electromagnetic fuel-delivery regulator 11 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Resistor bank 12 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electrohydraulic shut-off device EHAB 13 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Drive stage selection 16 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Turbo air and coolant temperature sensors 17 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Turbo pressure sensor (51.27421–0181) 18 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
RPM sensor 19 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Notes on operation 20 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Self-diagnosis 21 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Flash code 22 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
List of checking procedures 24 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Troubleshooting chart 27 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Troubleshooting program 30 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Test 31 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Drive stage selection 31 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
RPM sensor 32 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Boost pressure sensor 33 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Control rod position sensor 34 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Coolant temperature sensor 35 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Resistor bank 36 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Fuel volume regulator 37 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Auxiliary rpm sensor 38 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Charge-air temperature sensor 39 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Undervoltage 40 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Control unit 41 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Engine overspeed 42 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
EDC control box for idle speed adjustment 43 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CAN system (control unit) 44 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Main relay 45 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Atmospheric pressure sensor (in control unit) 46 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
CAN system (TSC1-FM message) 47 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Control unit, EEPROM processor 1 fault 48 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Control unit, EEPROM processor 2 fault 49 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Control unit (processor run-on) 50 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Control unit watchdog run-on fault 51 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Control rod position sensor – loose contact 52 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
PBM interface 53 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electrohydraulic shut-off device EHAB 54 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2
Contents
Plug connections 55 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Rating data sheet 57 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Revision list 57 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Scope 57 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
General features 57 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Temperature range 58 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Mechanical characteristics 59 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electrical ratings 60 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Immunity to interference 61 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Resistance to motor vehicle-specific liquids / fluids 62 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Mechanical test data 62 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Service life test 62 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Connection diagram 63 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Index 66 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3
Safety information
General
Important safety regulations are summarized in this quick-reference overview and arranged by topic to effectively convey the knowledge necessary to avoid accidents causing injury, damage or environmental hazard.
The engine operating manual contains further information.
Important:
Should an accident occur despite all precautionary measures, particularly one involving contact with corrosive acid, penetration of fuel under the skin, scalding by hot oil, antifreeze splashing into the eyes etc. you
must seek medical assistance immediately.
1. Instructions for avoiding accidents likely to cause injury
Only authorized and qualified personnel are permitted to carry out inspection, adjustment and repair work
D Secure and chock vehicles to prevent the vehicle rolling
D Firmly secure units and assemblies on disassembly
D Only authorized personnel are permitted to start and operate the engine
D Do not stand too close to rotating parts while the engine is running
Wear close-fitting working clothes
D Do not touch a hot engine with bare hands:
Risk of burns
D Keep area surrounding engine, ladders and stairways free of oil and grease.
Accidents caused by slipping can have serious consequences
D Only work with tools which are in good condition. Damaged or worn spanners and
wrenches can slip off: Risk of injury
D Persons must not stand under an engine suspended on a crane hook. Keep lifting
gear in perfect condition
D Only open coolant circuit once the engine has cooled down. Follow the instructions
given under “Care and Maintenance” in the Operating Manual exactly if it is not possible to avoid opening the coolant circuit with the engine at operating temperature
4
Safety information
D Do not tighten or loosen pipes and hoses that are under pressure (lubricant circuit,
coolant circuit and any downstream hydraulic oil circuits): Risk of injury caused by
liquids escaping under pressure
D Do not place hands under the fuel jet when checking injection nozzles.
Do not inhale fuel mist
D Always disconnect battery when working on the electrical system
D Do not use rapid charger to start the engine. Rapid charging of batteries is only per-
mitted with the positive and negative leads disconnected!
D Disconnect batteries only with the ignition turned off
D Observe manufacturer ’s instructions for handling batteries.
Caution:
Battery acid is toxic and corrosive. Battery gasses are explosive
D Only use suitable measuring instruments to measure voltages! The minimum input
resistance of a measuring instrument should be 10 MΩ
D Only disconnect or connect wiring harness connectors on electronic control units with
the ignition turned off!
Disconnect batteries and connect the positive lead to the negative lead such that they are
electrically conductive before carrying out any electric welding work. Earth the welding set
as close to the weld as possible. Do not place cables of welding set parallel to electrical
lines in the vehicle.
Refer to the “Welders Code of Practice” for further accident prevention measures.
D When carrying out repaint jobs, electronic components may be subject to high tem-
peratures (max. 95°C) for only very short periods; a period of up to approx. 2 hours is
permissible at a max. temperature of 85°C, disconnect batteries
Limitation of liability for parts and accessories
In your own interest, we strongly recommend you use only accessories and original MAN parts expressly
approved by MAN for your MAN engine. The reliability, safety and suitability of these parts and accessories
have been tested specially for MAN engines. Despite us keeping a constant eye on the market, we cannot
assess and be held responsible for these properties in other products, even if they bear TÜV (German testing and inspection institute) approval or any other official approval in any particular case.
Laying up or storage
Special measures must be implemented in accordance with MAN Company Standard M 3069 Part 3 if engines are to be laid up or placed into storage for more than 3 months.
5
Electronic diesel control
Electronic diesel control EDC
General
The requirements set by customers and legislation in respect of fuel consumption, exhaust emission and
noise characteristics etc. on diesel engines have grown over the years and will be even more stringent in
the future.
The fact that conventional mechanical injection systems have reached their performance limits has made
electronically controlled fuel injection systems necessary.
Such systems increase engine efficiency, improve driving comfort and lessen the burden on the environment.
EDC (Electronic Diesel Control) meets these requirements.
6
System description EDC M(S) 5
System description
Engine
speed 1
Engine
speed 2
Drive stage
selection
Boost
pressure
Power supply
Intermediate
engine speeds
Charge air intake
temperature
Coolant
temperature
Control unit
PWM signal
terminal 30
Terminal 15
ISO diagnosis
Diagnosis
request
EHAB
Electrohydraulic cut-out
Diagnosis
warning lamp
CAN bus
Engine speed
The controller contains
– the linear solenoid
– the control rod position transducer
The linear solenoid is actuated by the electronic control unit. The control unit processes information which it
receives via
– the control rod position transducer
– the drive position selection
– drive stage selection
– coolant temperature sensor
– charge-air temperature sensor
– intermediate engine speed setpoint
– and the rpm sensors.
The diagnosis request push button and the EDC indicator lamp are used in detecting faults and signalling
them through a code.
An ISO interface provides a communication with the MAN-cats test and diagnostic computer.
The control unit, with its program adapted to the engine model concerned, determines the optimum setting
of the control rod from all the measured values.
To ensure the vehicle can still be driven to the nearest workshop in the event of one or several sensors fail-
ing, an emergency drive function is integrated in the control unit which, depending on the situation, makes it
possible to continue driving with restricted functions.
When the brakes are applied, the system operates as an intermediate engine speed controller with a cyclic
irregularity (P-degree) of 0, i.e. a set intermediate engine speed is maintained exactly provided the engine
develops sufficient power output for this purpose.
7
System description
The idle speed control operates in the same way as the intermediate engine speed control. The idle speed
is exactly maintained by means of the idle speed governor as long as the engine output is sufficient for this.
The regulated idle speed can be varied within certain limits.
Starting-fuel delivery is output when either a lower start recognition speed is exceeded. The starting fuel
volume and cold idle speed are limited as a function of the coolant temperature to avoid impermissible
smoke emission and unnecessary revving of the engine after starting.
8
Component description
Control unit plug connector
Pin arrangement
19 1. . . . . . . . . . . . . . . . . . . . . . .
37 20. . . . . . . . . . . . . . . . . . . . . .
55 38. . . . . . . . . . . . . . . . . . . . . .
Pin assignments of control unit plug connector
EDC Pin Connection to component (O=Output, I=Input)
1 Injection pump controller pin 8 O
Jumper to pin 2 (activation of fuel volume regulator) O
2 Jumper to pin 1 (activation of fuel-delivery regulator) O
3 Not used
4 Not used
5 Not used
6 Not used
7 Not used
8 Not used
9 Injection pump controller pin 5 (control rod position sensor, instrument coil)
10 Injection pump controller pin 1 (control rod position sensor, reference coil)
11 Injection pump controller pin 6 (control rod position sensor, centre pick-off)
12 Not used
13 Negative from control unit for (Sensor ground)
– rpm sensor
– turbo pressure sensor
– drive stage selection
– turbo air temperature sensor
– coolant temperature sensor
– resistor bank
14 Electrohydraulic shut-off valve (EHAB) O
15 Control unit power supply battery + (via main relay and fuse) I
16 Control unit power supply battery + (via main relay and fuse) I
17 Ground for auxiliary rpm sensor
18 Power supply battery –
19 Power supply battery –
20 EDC indicator lamp and diagnostic lamp O
21 RPM sensor (twisted with cable pin 13) I
22 Auxiliary rpm sensor (twisted with cable pin 17) I
23 Intermediate engine speed control ZDR 1 I
24 Not used
25 Not used
9
Component description
EDC Pin Connection to component (O=Output, I=Input)
26 Not used
27 Drive stage selection (signal) I
28 Engine speed signal output from control unit (square-wave pulses) O
29 Multiplex signal O
30 CAN-L
31 CAN-H
32 Not used
33 Turbo pressure sensor (supply) O
34 Turbo air temperature sensor I
35 Resistor bank
36 Turbo pressure sensor (signal) I
37 Not used
38 Not used
39 Empty fuel switch signal
40 External engine cut-out
41 Intermediate engine speed control ZDR 2 I
42 Not used
43 Not used
44 Speed control device I
45 Drive stage selection (supply)
46 Relay power supply batt.+ (main relay) O
47 Relay power supply n/o contact I
48 Diagnostic connection (K-link)
49 Diagnostic connection (L-link)
50 Not used
51 Resistor bank 3 kΩ
52 Assigned to batt.+ (to enable multiplex signal) I
53 Coolant temperature sensor I
54 Not used
55 Not used
10
Component description
Injection pump
The EDC injection pump consists of a heavy-duty version of a conventional injection stage of the wellknown Bosch P-pumps and, instead of the mechanical regulator, a flange-mounted electromagnetic fueldelivery regulator with a control rod position transducer.
Electromagnetic fuel-delivery regulator
Description:
The fuel-delivery regulator operates in conjunction with the P-pump. The most important component of the
fuel-delivery regulator is a linear solenoid whose armature acts directly on the control rod thus determining
the injection volume by means of the control position. When no power is applied, the control rod is held in
the stop position by means of a spring.
The other important component in the regulator is a control rod position sensor.
Injection pump
Control rod Control rod position sensor
Fuel delivery regulator
(linear solenoid)
Fuel-delivery regulator
2
7
1
6
3
4
5
11
Control rod position sensor
Plug connection
Component description
Resistor bank
On commercial vehicles, certain items of data are fed to the EDC which are not required for railway operation.
An example of such data is a signal from the tachograph (speedometer, tachograph) which is used for controlling or limiting the driving speed (see Page 36).
Some unused EDC connections must be closed by resistors since the EDC constantly conducts a signalrange check, as described on Page 21.
Interior circuit
3
1
2
5
6
4
R1 0.511 kOhm
R5 0.511 kOhm
R2 1.37 kOhm
R6 1.37 kOhm
R7 3.08 kOhm
R3 3.08 kOhm
R8 8.20 kOhm
R4 8.20 kOhm
8
9
7
2 84357691
12
Component description
Electrohydraulic shut-off device EHAB
The EHAB (electrohydraulic shut-off device) is a safety-relevant component.
The EHAB shuts off the fuel supply to the injection pump in the event of certain faults occurring in the EDC
system. The EHAB is connected into the fuel supply system between the delivery pump and pump suction
chamber. The EHAB reverses the delivery direction of the delivery pump so that the pressure in the suction
chamber is reduced rapidly thus interrupting the filling procedure.
Power is always applied to the EHAB during operation. The power circuit is interrupted by the EDC control
unit in order to activate the EHAB (e.g. for emergency engine shut-down).
For this reason, the ignition must be turned on when bleeding the fuel system by means of the presupply pump.
21
TÜV
2
1
Plug connection
Fi FP
43
56
13
Component description
Fuel circuit diagram – Engine running
Injection pump
Flame starting
system
11 11
10
6
9999
Suction
chamber
TUV
3
Fi
Fp
44
6
7
Pressure chamber
Injection nozzles
Engine
5
8
1 Fuel tank 7 Overflow valve 3.7–4.3 bar
2 Prefilter 8 Pre-delivery pump (hand primer)
3 Electrohydraulic shut-off device (EHAB) 9 Fuel hose NW12
(overrevving protection) 10 Magneto valve
4 Delivery pump (double acting) 11 Flame heater plugs
5 Fuel filter 12 Electric fuel pump
6 Overflow valve 2.0–2.5 bar 13 Overflow valve 1.0 bar
Caution:
Presupply pump integration in the fuel circuit should be checked according to pump type.
13
M
12
2
1
14
Component description
Fuel circuit diagram – engine shutoff using EHAB
Injection pump
Flame starting
system
11 11
10
6
Suction
chamber
T
UV3
Fi Fp
44
9999
6
7
Pressure chamber
Injection nozzles
Engine
5
8
1 Fuel tank 7 Overflow valve 3.7–4.3 bar
2 Prefilter 8 Pre-delivery pump (hand primer)
3 Electrohydraulic shut-off device (EHAB) 9 Fuel hose NW12
(overrevving protection) 10 Magneto valve
4 Delivery pump (double-acting) 11 Flame heater plug
5 Fuel filter 12 Electric fuel pump
6 Overflow valve 2.0–2.5 bar 13 Overflow valve 1.0 bar
Caution:
Presupply pump integration in the fuel circuit should be checked according to pump type.
13
M
12
2
1
15
Component description
Drive stage selection
Function
The drive stage selection device transfers driver’s requests in the form of voltages to the control unit.
The control unit then derives the corresponding engine speed or volumetric charge from these voltages.
Block diagram
Pin 13
Pin 39
Pin 13
Pin 27
U = Reference voltage, approx. 5 V from the EDC control unit
u = Setpoint
Pedal travel sensor simulation values
Lower idle speed: 257–539 mV / upper idle speed: 2944–4501 mV
Empty fuel switch: switch-on point at 569–976 mV (typically 800 mV)
top idle
speed
Pin 45
lower idle
speed
257 mV 976 mV 2944 mV 4501 mV [ mV ]
539 mV 569 mV
Fault registration
Empty fuel switch range
(typically 880 mV)
Exceptionally, the voltage “u” is produced electronically as drive position selection, or the setpoint selection
(drive position selection) takes place via the CAN bus.
16
Turbo air and coolant temperature sensors
Turbo air B197 (51.27421–0165)
Characteristic R=f (-í )
Component description
2
4
3
1
Plug connection
Coolant B124 (51.27421–0172)
Characteristic R=f (-í )
2
4
3
1
Plug connection
Function
The turbo air and coolant temperature sensors are NTC resistors. The coolant temperature sensor is located in the coolant circuit and the turbo air temperature sensor in the turbo air circuit after the intercooler.
They supply the control unit with information relating to the coolant and turbo air temperature.
17
Component description
Turbo pressure sensor (51.27421–0181)
1
Ground – Supply +
4
32
Output
Plug connection
Function
The pressure sensor element consists of an Si diaphragm which contains several piezo-resistive (pressuresensitive) semiconductor resistors. The pressure to be measured “deflects” the sprung diaphragms. As a
result, extended or compressed zones are created on the surface of the diaphragms. The action of these
forces changes the electrical ratings of semiconductor resistor arrays arranged in these zones. These values are a measure for the pressure to be measured.
Circuit diagram
Output +5 V
Pin 13 3336
Pressure
connection
18
Component description
RPM sensor
Housing: grey
Coding A
Function
The rpm sensor consists of a permanent magnet and a coil with a high number of windings. The magnet
“touches” the rotaring component to be measured, normally a crown gear or grooved ring gear, with its
magnetic field.
With the EDC M(S) 5 system, there are 6 grooves on the flywheel.
When a groove passes the sensor, the magnetic current is reduced. This generates an induction voltage in
the sensor coil which is measured by the electronic control. The distance between the sensor and the
grooved ring gear is approx. 1 mm.
Two rpm sensors are required to ensure reliable operation of the EDC system.
Both rpm sensors are installed in the flywheel housing.
A distinction is made between the rpm sensor and the auxiliary rpm sensor.
The rpm sensor is installed in the flywheel housing such that an rpm pulse is triggered 10° after TDC.
The auxiliary rpm sensor is installed in the flywheel housing in such a way that an auxiliary speed pulse is
triggered 18° after TDC. The signals of the auxiliary rpm sensor are used only for redundant engine speed
sensing.
2
Plug connection
RPM sensor (1)
1
Auxiliary rpm sensor (2)
21
Plug connection
Housing: black
Coding B
Caution:
Do not confuse installation locations of the rpm sensor (1) and the auxiliary rpm sensor (2), nor the “+”
and “–” wires of the sensors.
19
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