Notes on fault memory, electronically-controlled in-line fuel injection (IFI) - AD07.12-P-2000-01B

• Fault memory: Fault readout Current faults:  have a grey  grid background Faults in memory:  have a light  background

All inputs/outputs are tested for plausibility during operation.

All faults which exist for more than 0.5 seconds are stored in the fault memory of the IFI control module (N3/7), except for control deviations (boost pressure, exhaust gas recirculation etc.) where the fault is only stored after 5 - 10 seconds.

The faults remain stored with ignition "OFF" or after disconnecting the vehicle battery.

In the case of major faults the Electronic Power Control malfunction indicator lamp (EPC, A1e43) is illuminated.

version 

If there are faults which are relevant to exhaust emissions, the

"CHECK ENGINE" malfunction indicator lamp (A1e26) comes on and CHECK-ENGINE ENGINE ELECTRONICS

comes on in the multi-function display.

The faults are identified by an OBD fault code: refer to electronically-controlled in-line fuel injection (IFI) diagnosis fault memory

• EGR lifting sender (B28/3) or hot film MAF sensor (B2/5)
• EGR vacuum transducer (Y31/1)
• Boost pressure control/pressure control flap vacuum transducer (Y31/5)

Fault ambient data 

The fault ambient data at the time the fault was stored can also be displayed with the HHT. Only the ambient data is stored which existed when the fault occurred for the first time. The ambient data is distributed over several display screens (up to 8 display screens), the last two display screens being intended purely for development.

Display screens with the result √/F explain the fault causes, e.g.

• voltage too high
• voltage too low
• signal too strong
• signal too weak
• value implausible

Emergency running mode in the event of signal failure 

In the event of failure of important input signals or other serious faults, the IFI control module changes to emergency running mode.

Emergency running mode may result in:

• Reduction in engine output/reduction in maximum engine speed
• Deactivation of smooth running control
• Failure of exhaust-gas recirculation
• Failure of cruise control
• Failure of boost pressure control

Notes on HHT 

• Loose contacts 

  Loose contacts are stored if they occur several times during a particular period of time. They can therefore only occur as stored faults and never as current faults.

• Specified values 

  All specified values relating to the actual values displayed in the HHT are given in the Diagnosis Manual, Diesel Engine, Volume 1.1 Chapter A.

• Actual values of engine coolant temperature 

  In the event of an open-circuit or short-circuit, the system switches over immediately from the current actual value to a substitute value which is very close to the actual value. Consequently, a fault cannot be clearly recognized. It is only possible to read the fault from the fault memory.

• Actual value of engine speed 

  For the engine speed, the specified  idle speed value calculated by the control module appears under menu item 3/1 Closed throttle position, on the left of the HHT display, and the actual  engine speed value appears on the right.

• Actual value of injected fuel quantity 

  For the injected fuel quantity, the specified  injected fuel quantity value calculated by the control module appears under menu item 3/2 Testing engine, on the left of the HHT display and the actual  injected fuel quantity value appears on the right.

• Actual value of distributor pipe pressure 

  The distributor pipe pressure appears on the HHT display under menu item 3/2 Testing engine. The specified distributor pipe pressure value calculated by the control module appears on the left and the actual distributor pipe pressure value appears on the right.

  The values should only deviate slightly from each other. The permissible tolerances are not yet specified.

Note on stage 2a drive authorization system (model 140) and note on stage 3 drive authorization system (model 210) 

• The stage 2a drive authorization system is only activated by the RCL control module via the CAN data bus to the IFI control module.

The stage 3 drive authorization system is only activated by the electronic ignition switch control module via the CAN data bus to the IFI control module.

After the drive authorization system has been activated, the IFI control module immobilizes the injection system. The stage 2a or 3 drive authorization system is activated and de-activated with the ignition key.

The IFI control module and the RCL or EZS control module are permanently locked together by an identification code. This identification cannot be erased (refer to HHT actual values "Drive authorization system" menu item 3/7). It is therefore not possible to replace the IFI or RCL or electronic ignition switch control module in another vehicle on a trial basis.

Before starting for the first time, a variant coding must  be carried out on the IFI control module using the HHT.

The VIN number is also entered in the IFI control module when locking.

If a new IFI control module is installed for test purposes, a maximum of 40 start procedures can be performed, then the control modules will be permanently locked together.

Variant coding with HHT 

a) The variant coding can only be performed automatically and manually with the Hand-Held Tester, refer to (Menu item 5 "Variant coding").

• Automatic 

  Before removing the IFI control module, read out the code number present with the HHT. When the new control module has been installed, input the stored code number (menu-guidance in HHT).

• Manual 

  If the code number cannot be read out, the vehicle version must be established. The appropriate code number is to be obtained from the parts microfilm, group 54 and input manually with the HHT.

  Take the following vehicle versions into account when coding:

  • Vehicle model
  • 5-speed automatic transmission with cruise control
  • National version

When the new control module is returned to the Parts Store, the code number must be erased.

The installation of a control module from another vehicle on a trial basis is not  possible.

The installation of a control module from the Parts Store on a trial basis is possible.

Notes on fault memory, electronically-controlled in-line fuel injection (IFI) 

An operating cycle is achieved when the following requirements are met:

• Engine coolant temperature is > 60°C
• Engine switched off
• Wait for 5 seconds afterrun
• Start engine
• Allow engine to idle for 2 minutes
• Full throttle acceleration in drive position D up to 55 mph
• Drive on overrun down to 40 mph