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 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 pressure 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 Engine control module (IFI) (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. - 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 only rarely 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, air and fuel temperatures: 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 X (DAS) The activation of the drive authorization system stage X takes place only from the DAS control module (N54/1) via the CAN data bus to the engine control module (IFI) (N3/7). After activation of the DAS stage X, the engine control module (IFI) (N3/7) renders the fuel injection system inoperable. The activation or deactivation is accomplished with transponder technology via the ignition key. As soon as the ignition key is turned to position "2" in the steering lock, the DAS control module (N54/1) receives a signal and the fuel injection system is made operative via the CAN data bus. The engine control module (IFI) (N3/7) and the DAS control module (N54/1) 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 engine control module (IFI) (N3/7) or the DAS control module (N54/1) by swapping control modules from another vehicle is no longer possible. If a new engine control module (IFI) (N3/7) 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 engine control module (IFI) (N3/7) can no longer be used in any other vehicle. Before the first engine start, version coding must be performed on the engine control module (IFI) (N3/7) 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 engine control module (IFI) (N3/7), 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 5-speed automatic transmission With cruise control 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 Turn off engine Wait 5 seconds (internal control module test) Start engine Run engine at idle speed for 20 seconds In selector lever position P/N raise engine speed to 2500 rpm and release accelerator pedal and allow engine to return to idle speed. Accelerate (full load acceleration) vehicle in transmission range D to approx. 53 mph (85 km/h) and then decelerate (coasting) to approx. 37 mph (60 km/h).

Prerequisite for DTC memory readout 1. Review section 11, 12, 21 , 22, 23 , 2. Fuse on relay module (K40) in order, 3. Connect HHT to data link connector (X11/4, 38-pole) according to connection diagram (see section 0), Yellow wire to socket 4. 4. Review electrical wiring diagram: PE07.00-P-1100A Electrical wiring diagram: Electrical Troubleshooting Manual, Model 210, Volume 1

DTC	OBD DTC	Possible cause	DTC Description	Test step/Remedy 1)
		No malfunction in system		-
		Pressure sensor (B28)	13 > 1	23 5.0
		IAT sensor (B17)	13 > 2	23 4.0
		ECT sensor (B11)	13 > 3	23 3.0
		Fuel temperature sensor (Y1/1b1)	13 > 4	23 12.0
		CAN data bus	13 > 5	23 13.0
		Transmission failure		see DM, Chassis and Drivetrain, Volume 1, section 2
		Transmission failure		see DM, Chassis and Drivetrain, Volume 1, section 2
		Atmospheric pressure sensor in control module	13 > 6	N3/7
		Fuel quantity actuator (Y23/1)	13 > 7	23 7.0
		CAN communication, ETC or ETS interrupted	13 > 8	23 13.0
		IFI/DFI accelerator pedal position sensor (R25/2)	13 > 9	23 9.0
		Fuel rack position sensor (Y23/1l1)	13 > 10
		CKP sensor (IFI/DFI) (L5/6)	13 > 11	23 6.0
		EGR lifting sender (B28/3)	13 > 12	23 17.0
		EGR control	13 > 13	23 27.0
		Pressure control flap vacuum transducer (Y31/2)	13 > 14	23 20.0
		Shifting induction pipe switchover valve (Y22/6)	13 > 15	23 21.0
		Resonance intake line switchover valve (Y22/7)	13 > 16	23 23.0
		Preglow control	13 > 17	23 14.0
		Glow plug failure, cylinder 1 - 2 Glow plug failure, cylinder 3 - 4 Glow plug failure, cylinder 5 - 6	13 > 18	23 16.0
		Preglow control module (N14/2)	13 > 19	23 15.0
		CC switch (S40)		23 10.0
		Voltage supply missing or relay module (K40)	13 > 20	23 18.0
		Engine control module (IFI) (N3/7)	13 > 21	N3/7
		Engine control module (IFI) (N3/7) voltage, circuit 15	13 > 22	23 19.0
		Engine control module (IFI) (N3/7) or fuel metering actuator (Y23/1k1) or fuel rack position sensor (Y23/1l1)	13 > 23	23 7.0 23 8.0
		Engine control module (IFI) (N3/7), supply voltage		23 1.0 23 2.0
		Engine control module (IFI) (N3/7) or not properly coded	13 > 24	see HHT "Version Coding" menu selection 5
		IFI/DFI electrohydraulic shut-off actuator (Y1/1)	13 > 25	23 11.0
		Drive authorization signal (DAS)		see HHT actual values "Drive Authorization" menu selection 3/7

1) Observe Preparation for Test, see 22 .