Diagnostic Manual, Diesel Engines, Volume 1.1
Diagnosis - Diagnostic Trouble Code (DTC) Memory
Note regarding diagnostic trouble code (DTC) readout:
 DTC memory: Fault display
Actual faults : are on a grey background
Stored faults : are on a light background
The signal plausibility is checked on all input and output connections during operation.
All malfunctions which occur are stored in the diagnostic trouble code memory of the IFI control module (N3/7).
The DTC memory remains active even if the ignition is turned "OFF" or the vehicle's battery is disconnected.
With emission related faults the CHECK ENGINE MIL (A1e26) lights up
and/or the multifunction indicator displays: CHECK ENGINE
ENGINE ELECTRONICS.
The faults are identified with an OBD failure code: See listing starting on page 5.
Such faults are for example:
- EGR lifting sender (B28/3)
- EGR valve vacuum transducer (Y31/1)
- Pressure control flap vacuum transducer (Y31/2)
Fault freeze frame data
Additionally, ambient conditions present at the time the fault occurs, can be displayed with the HHT. Only those freeze frame data are stored which were present when the fault first occurred. The freeze frame data may be indicated on several screen displays (up to 8 screen displays). The last two screen displays are for development purposes only.
Screen displays with the result  /F indicate the cause of the fault e.g.
Voltage too high
Voltage too low
Signal too large
Signal too small
Value implausible
Substitution for missing signals.
The IFI control module (N3/7) replaces missing input signals with substitute values based on other signals available in order to maintain system function.
The substitute values may result in:
- Performance reduction/reduction of maximum engine rpm.
- Switching off anti-vibration control.
- EGR system malfunction.
- Cruise control malfunction.
- Intake MAP control malfunction. |
Notes for HHT
Loose connections
Loose connections are stored if they occur several times in a certain time period. Therefore, they can appear only as stored DTC's and never as actual DTC's.
Nominal values
All nominal values relative to the actual values shown on the HHT are listed in the Diagnostic Manual, Diesel Engines, Volume 1.1,
section A.
Actual value for engine coolant temperature
In case of an open or short circuit, the actual value is immediately replaced by a substitute value which is very close to the actual value. Therefore, a fault can not be recognized clearly. A readout of the fault is possible only via the diagnostic trouble code (DTC) memory.
Actual value for engine rpm
In case of the engine rpm's, the HHT display indicates under menu selection 3/1 the closed throttle (idle) speed nominal value calculated by the control module on the left and the rpm actual value on the right.
Actual value for injection quantity
In case of the injection quantity, the HHT display indicates under menu selection 3/2 engine test the injection quantity nominal value calculated by the control module on the left and the injection quantity actual value on the right.
Actual value for intake manifold pressure
In case of the intake manifold pressure, the HHT display indicates under menu selection 3/2 engine test the intake manifold pressure nominal value calculated by the control module on the left and the intake manifold pressure actual value on the right.
The values should differ from each other only slightly. The permissible tolerances are presently unknown.
Notes regarding the Drive Authorization System Stage 2 (DAS)
The activation of the drive authorization system stage 2 takes place only from the RCL control module via the CAN data bus to the IFI control module.
After activation of the DAS, the IFI control module renders the fuel injection system inoperable. This drive authorization system can only be activated or de-activated using either the IR transmitter or the master key.
The IFI control module and the RCL control module are permanently matched to one another via an identification code. This identification code can not be erased (see HHT actual value "drive authorization system" menu selection 3/7).
Troubleshooting of an IFI control module or the RCL control module by swapping control modules from another vehicle is no longer possible.
If a new IFI control module is installed for test purposes only, a maximum of 40 engine starts can be performed before the control modules are permanently locked with each other. After 40 engine starts, the IFI control module can no longer be used in any other vehicle.
Before the first engine start, version coding must be performed on the IFI control module with the HHT. After that, identification must be initiated. |
Version coding with HHT
a) Version coding can be performed automatically and manually only with the Hand-Held Tester (see menu selection 5 "Version coding").
Automatic
Before removing the IFI control module, read existing version code with HHT. After installation of the new control module, enter the previously read version code (menu program in HHT).
Manual
If the code number can not be read, the vehicle equipment/version must be determined. The corresponding code number is obtained from the Spare Parts Microfiche, Group 54 and manually entered with the HHT.
The following vehicle version data must be observed for coding:
Vehicle model
ABS
Manual transmission
4-speed automatic transmission
With cruise control
Without cruise control
ETS
Country version
When returning a new control module to a PDC, the code number must be erased.
Trial installation of a control module from an other vehicle is not possible.
Trial installation of a new control module from spare parts stock is possible, but only to a maximum of 40 engine starts. After 40 engine starts, the control module is permanently assigned to the vehicle.
Operating Cycle  version only
One operating cycle is reached if:
Engine coolant temperature > 60o C
Engine rpm for 5 seconds at 2500 rpm
Ignition OFF for 5 seconds
Engine rpm for 5 seconds at 2500 rpm
Ignition OFF for 5 seconds
Engine rpm for 5 seconds at 2500 rpm
See HHT Menu 3/8 Memory storage enablement OBD II. |
Prerequisite for DTC memory readout
1. Fuse on relay module (K40) in order.
2. Connect HHT to data link connector (X11/4, 38-pole) according to connection diagram (see section 0).
Yellow wire to socket 4.
Electrical wiring diagram:
Electrical Troubleshooting Manual, Model 210 |
DTC
 |
OBD
DTC |
Possible cause |
DTC
Description |
Test step/Remedy 1) |
| |
|
No malfunction in system |
|
- |
    |
|
Pressure sensor (B28) |
 13 > 1 |
23  6.0 |
| |
|
IAT sensor (B17) |
13 > 2 |
23 5.0 |
| |
|
ECT sensor (B11/4) |
13 > 3 |
23 4.0 |
 |
|
Fuel temperature sensor (Y1/1b1) |
13 > 4 |
23 23.0 |
 |
|
EGR, Pressure control, intake manifold pressure |
13 > 5 |
23 31.0 |
| |
|
VSS |
|
23 15.0 |
 |
2) |
CAN data bus |
|
23 25.0 |
  |
|
Stop lamp switch (S9/1) |
|
23 12.0 + 13.0 |
| |
|
Atmospheric pressure sensor in control module |
13 > 6 |
N3/7 |
 |
|
Fuel quantity actuator (IFI) (Y23/1) |
13 > 7 |
23 8.0 |
| |
|
IFI accelerator pedal position sensor (R25/2) |
13 > 8 |
23 10.0 |
| |
|
Fuel rack position sensor (Y23/1l1) |
13 > 9 |
23 9.0 |
| |
|
CKP sensor (IFI) (L5/6) |
13 > 10 |
23 7.0 |
| |
|
EGR lifting sender (B28/3) |
13 > 11 |
23 30.0 |
| |
|
Pressure control flap vacuum transducer (Y31/2) |
13 > 12 |
23 32.0 |
| |
|
Resonance intake line switchover valve (Y22/7) |
13 > 13 |
23 26.0 |
| |
|
Resonance intake manifold switchover valve (Y22/6) |
13 > 14 |
23 27.0 |
| |
|
Preglow control |
13 > 15 |
24 1.0 - 4.0 |
| |
|
Cruise control switch (S40) |
|
23 16.0 |
| |
|
Voltage supply missing or relay module (K40) |
|
23 3.0 |
| |
|
IFI control module (N3/7) |
13 > 16 |
N3/7 |
| |
|
IFI control module (N3/7) voltage, circuit 15 |
13 > 17 |
23 2.0 |
| |
|
IFI control module (N3/7) |
13 > 18 |
N3/7 |
| |
|
IFI control module (N3/7) or fuel metering actuator (Y23/1k1) or fuel rack position sensor (Y23/1l1) |
13 > 19 |
23 8.0 + 9.0 |
| |
|
IFI control module (N3/7) supply voltage |
13 > 20 |
23 1.0 |
| |
|
Control module or not coded |
13 > 21 |
see HHT "version coding"
menu selection 5 |
| |
|
Electrohydraulic shut-off actuator (Y1/1) |
13 > 22 |
23 22.0 |
| |
|
CHECK ENGINE MIL |
|
23 17.0 |
| |
|
Drive authorization signal |
|
see section A4 or HHT actual values "drive authorization" menu selection 3/7 |
| |
|
Starter lock-out/backup lamp switch (S16/1) |
|
23 11.0 + 29.0 |
| |
|
Modulating pressure switchover valve (AT/CC) (Y3/4)or upshift delay switchover valve (AT/CC) (Y3/5) |
|
23 19.0 + 21.0 |
| |
|
Upshift delay switchover valve (AT/CC) (Y3/5) |
|
23 21.0 |
1) Observe Preparation for Test, see 22 .
2) The DTC P0600 can be displayed even if no malfunction is present |
|
Printable version
