Electronic engine control (EMR) diagnosis troubleshooting

AD30.33-W-5000A

Electronic engine control (EMR) diagnosis troubleshooting

27.10.97



Only perform the troubleshooting without measuring instruments described in the following, if no HHT or vehicle with FDS/FSS is available.

It also permits a limitation of the fault source(s) in the EMR system and should always be carried out before "Testing components at the connectors"



If the warning lamp comes on when the engine is running, the control unit has recognized a fault in the EMR system. The fault code and the actual values can only be read out using the HHT or on vehicles with FDS/FSS. For coding of code numbers or the required test steps, refer to fault code summary. If no fault code is stored, the large number of actual values allows for effective fault limitation.

Electronic engine control (EMR) diagnosis, previous knowledge

AD30.33-W-2000A

Electronic engine control (EMR) diagnosis, function check using actual values

AD30.33-W-3000A

Electronic engine control (EMR) diagnosis, fault memory

AD30.33-W-4000A

Troubleshooting with actual value, cruise control/Temposet, EMR

With HHT

AD30.33-W-5000-01A

With FDS/FSS

AD30.33-W-5000-01B



The connection of electrical appliances to the fuse of the EMR can render the EMR system inoperative in the event of short-circuit or overload (if necessary, not until during operation).



On-board voltage 24 V (acid density 1.16)



Indicator lamp for auxiliary appliances must go out



Compressed-air at least 5.5 bar



If the trip to the workshop was made with the emergency driving device:

Notes on emergency driving device, EMR

AD30.33-W-2000-01A

Troubleshooting

Test step/Scope of test

Operation/Requirement

Specified value

Possible cause/Remedy

1

Indicator lamp, EMR (H9)

Switch on ignition

Indicator lamp comes on

Replace light bulb in indicator lamp, EMR (H9), replace if necessary.

2

EMR system by means of indicator lamp, EMR (H9)

Ignition: ON

Start engine/engine running

Indicator lamp goes out

Control unit reports a fault in the EMR system.

AD30.33-W-4000A

3

Engine speed increase

(cruise control)

Ignition: ON

Engine running. Press cruise control lever forwards several times.

Engine speed increases audibly (or can be seen on rev counter).

Cruise control steering column switch, actuator motor disengaged/defective, electrical module, MN-module.

4

Engine speed increased by means of foot throttle actuator.

Ignition: ON

Engine running. Operate accelerator pedal.

Engine speed varies depending on the accelerator pedal position.

Foot throttle actuator disengaged/defective,

Electrical module.

5.0

Engine speed reduction at 3rd brake

(engine brake function)

 On production and special equipment ABS only

Ignition: ON

Engine running. Operate engine brake and accelerator pedal at the same time.

It is not permitted to "pick up speed".

(engine runs at idle speed)

On production vehicle: Fuse F9 on L-module, pressure switch on throttle flap valve, pneumatic error (foot-operated switch, no compressed-air).

On vehicle with ABS: B-module (ASR), engine brake foot-operated switch.

5.1

Engine speed reduction at 3rd brake

(engine brake function)

 Only on special equipment constant throttle

Ignition: ON

Engine running. Operate engine brake and accelerator pedal at the same time. Connect bridges of terminal 30 on relay K6 (A31) to V1 (2/1, +).

It is not permitted to "pick up speed" (engine running at idle speed).

Fuse F4/A3 or F2/A3 (depending on version). Speed switch (S38), diode V1, V2, relay K6 (A31), K3 (A32, depending on version).

Engine brake's foot-operated switch (S52).

Uprated engine brake switch (S39).

5.2

Engine speed reduction at 3rd brake

(Retarder engine brake function)

 Only on special equipment retarder 115H (Voith)

Ignition: ON

Engine running. Operate retarder stage

1 – 5 and accelerator pedal at the same time.

Connect bridges of terminal 30 on relay K6 (A31) to V1 (2/1, +) in connection with constant throttle only.

No "speed is picked up" (engine runs at idle speed).

Fuse F4/A3 or F2/A3 (depending on version)

Relay K6/A31,

Retarder control unit,

Retarder steering column switch in connection with constant throttle, refer to 5.1.

6

Temposet function, kickdown switch and idle throttle switch in foot throttle actuator.

Ignition: ON

1. Drive vehicle at approx. 32 km/h and set this maximum speed with Temposet button.

The set maximum speed cannot be exceeded even at full throttle at the foot throttle actuator.

Cruise control steering column switch,

C3-signal from I-module/tachograph is missing

Electrical module (control unit)

2. Operate kick-down position on foot throttle actuator briefly (then in idle position).

Set maximum speed is exceeded.

Kickdown switch, electrical module.

3. Operate accelerator pedal up to full throttle.

The set maximum speed cannot be exceeded again.

Idle throttle switch, electrical module.

7

Cruise control

Ignition: ON

1. Drive vehicle at 46 – 50 km/h and set this speed with the Cruise control control lever.

Set speed is maintained without "opening the throttle".

Cruise control steering column switch, C3-signal from I-module/tachograph missing, clutch stop lamp switch, electrical module (control unit). When connected to control unit:

Retarder recognition (V1, 10/4), neutral recognition (I, 4/4), reduction input (VII, 18/11).

2. Operate accelerator pedal.

Set speed can be exceeded.

Foot throttle actuator, electrical module

8

Cruise control switched off when braking

Ignition: ON

Drive vehicle with cruise control (46 – 50 km/h) and brake gently.

Cruise control is switched off.

Stop lamp switch (S8)

9

Cruise control switched off when using the clutch

Ignition: ON

Resume cruise control speed (control lever upwards) and operate clutch.

Cruise control is switched off.

Clutch switch.

Cruise control is switched off.

No shut-off on test step 8 and 9

Fuse F4/A3, electrical module, cable open-circuit.

10

Cruise control switched off at 3rd brake

Ignition: ON

Resume cruise control speed and operate engine brake or retarder.

Cruise control is switched off

Cruise control is switched off.

Depending on equipment, refer to 5.0 to 5.2.

Re 5.2 with retarder input, retarder recognition.

11

Cruise control switched off using cruise control switch

Ignition: ON

Resume cruise control speed and press cruise control control lever downwards (OFF position).

Cruise control is switched off.

Cruise control is switched off.

Cruise control switch (S27)

12

Cruise control switched off using neutral position (on special equipment automatic transmission only)

Ignition: ON

Resume cruise control speed and briefly shift into neutral.

Cruise control is switched off.

Neutral switch in transmission

Wiring to connection 4/4 on connector I.

13

Speed increase on special equipment power take-off

Ignition: ON

Operate parking brake and allow engine to run (idle).

Switch on switch for power take-off and if necessary, for speed increase.

Speed increases to set (programmed) value.

AD30.33-W-6001-20B

AD30.33-W-6001-20C

14

Parking brake signal when speed increases (on special equipment power take-off only)

Ignition: ON

Parking brake released (secure vehicle to prevent it from rolling away).

Switch on switch for power take-off and if necessary, for speed increase.

Speed does not increase.

AD30.33-W-6001-20B

AD30.33-W-6001-20C

15

Retarder switch off on special equipment retarder

Ignition: ON

On test trip, shift retarder into stage 1 – 5, then operate accelerator pedal gently.

Retarder is switched off.

Relay K5/A31

16

Speed increase by means of hand throttle actuator.

Ignition: ON

Apply parking brake and switch on power take-off.

Operate hand throttle actuator up to max. position.

Speed increases up to set limit speed.

AD30.33-W-6001-01B

AD30.33-W-6001-01C

AD30.33-W-6001-01D

AD30.33-W-6001-01E