Diagnostic Manual, Chassis and Drivetrain,
Volume 3
Diagnosis - Complaint Related Diagnostic Chart
WARNING!
Life threatening injures possible due to vehicle slipping or toppling off while on lift.
Prior to lift vehicle completely (wheels still in contact with floor), ensure that the vehicle is centered within the lift columns and lift arm supports are correctly placed unto the vehicle contact points.
Preparation for Test:
1. Review section 0, 13, 21, 22, 23
2. Review Important Data Charts on pages 13/2, 13/3, 13/4
|
Complaint/Problem |
Possible cause |
Test step/Remedy 1) |
ESP MIL (A1e42) or ABS MIL (A1e17) illuminates with engine running. |
|
Read DTC memory,
12 |
BAS/ESP MIL (A1e47) or ABS MIL (A1e17) illuminates while driving and does not go out |
|
Read DTC memory,
12 |
ESP MIL (A1e42) or ABS MIL (A1e17) illuminates while driving and then goes out |
Vehicle system voltage < 11 V, too many electrical consumers in use. |
Check generator (G2),
Read DTC memory,
12 |
ESP MIL (A1e42) or ABS MIL (A1e17) does not illuminate with ignition turned on |
Lamp,
Wiring. |
Read DTC memory,
12
Read DTC memory for instrument cluster, using HHT |
ABS MIL (A1e17) comes on with engine running after brake test or dynamometer use |
Implausible wheel speed signal due to different rpm at front and rear axles. |
Read, erase DTC memory
12 |
ESP MIL (A1e42) illuminates after the following causes (see Possible Causes) and upon DTC read-out using the HHT, the DTC is displayed |
Driving through steep turning curves,
Vehicle collision,
Vehicle spin-out on slippery road surfaces,
as a result: the DTC can be ignored. |
Read, erase DTC memory
|
ESP MIL (A1e42) illuminates and after reading-out the DTC's via the HHT, the DTC and at least one additional DTC between and is/are displayed. |
Short circuit in more then one of the solenoid valves of the hydraulic unit or
short in the wiring harness
If two of the solenoid valves have a short circuit, then the voltage supply to all the solenoid valves is shut-off.
|
Check all the solenoid valves of the hydraulic unit along with the corresponding wiring for solenoid valves for any short circuits. |
1) Observe Preparation for Test, see 22. |
CAN signal |
Type of Information |
ABS/ETS/ESP status |
Brake pad wear sensor indicator lamp
Parking brake warning lamp
ABS MIL
System fault or diagnostics
Stop lamp switch (S9/1):
Brake pedal not pressed,
Brake pedal depressed,
No signal
Cruise control OFF
ABS/ETS/ESP functions OK
ABS/ETS/ESP function OFF |
Left front wheel speed signal |
Wheel rpm |
Right front wheel speed signal |
Wheel rpm |
Left rear wheel speed signal |
Wheel rpm |
Right rear wheel speed signal |
Wheel rpm |
Left front wheel speed signal for cruise control |
Wheel rpm |
Right front wheel speed signal for cruise control |
Wheel rpm |
CAN signal |
Type of Information |
ABS status |
Cruise control function OFF
ABS/ETS/ESP functions OK
ABS/ETS/ESP function OFF
System fault or diagnostics |
ETS/ASR/ESP status |
Brake pad wear sensor indicator lamp
Parking brake warning lamp
ABS MIL
ETS/ASR/ESP MIL
ASR/ESP OFF MIL
Wheel spin or ASR/ESP active (MIL blinks)
Stop lamp switch (S9/1):
Brake pedal not pressed,
Brake pedal depressed,
No signal
ASR request: "2nd gear start"
ASR request: "hold in gear"
Rapid ASR control function
Increase in: engine braking regulation (EBR)
Decrease in: engine braking regulation (EBR)
Cruise control OFF
ASR functions OK
ABS/ASR function OFF
System fault or diagnostics |
Left front wheel speed signal |
Wheel rpm |
Right front wheel speed signal |
Wheel rpm |
Left rear wheel speed signal |
Wheel rpm |
Right rear wheel speed signal |
Wheel rpm |
Left front wheel speed signal for cruise control |
Wheel rpm |
Right front wheel speed signal for cruise control |
Wheel rpm |
CAN signal |
Type of Information |
From which control module |
Engine status |
Engine rpm |
Engine control module |
Engine status |
Required engine torque for traction control |
Engine control module |
Engine status |
Atmospheric pressure |
Engine control module |
Engine status |
Acknowledge engine moment request |
Engine control module |
Engine status |
Accelerator Pedal value |
Engine control module |
Engine status |
Indicated engine moment |
Engine control module |
Engine status |
Engine friction moment |
Engine control module |
Engine status |
Maximum engine moment |
Engine control module |
Vehicle version code |
Model
Chassis
Engine
Transmission |
Engine control module |
Transmission status |
Actual gear
Requested gear |
Electronic transmission control (ETC) |
Transmission status |
Rear Drive
All wheel drive |
Electronic transmission control (ETC) |
Transmission status |
Intial shift request
Transmission in emergency limp-home-mode |
Electronic transmission control (ETC) |
Transmission code |
Large transmission
Small transmission |
Electronic transmission control (ETC) |
Transmission status |
Torque converter lock-up: "locked"
Torque converter lock-up: "unlocked"
Torque converter lock-up: "slip" |
Electronic transmission control (ETC) |
|