WIS Document: 8984

| | Engine rpm signal to the MIU, TCS and AF22 control modules Fault symptom Diagnostic trouble codes generated in the MIU, TCS and/or AF22 systems | Diagnostic procedure | 1. | Start the engine and use the ISAT command "ENGINE RPM SIGNAL" in the "READ ON/OFF" menu. If the control module sends out engine rpm signals, the ISAT display should read "ACTIVE". If the ISAT shows "INACTIVE", turn to for further diagnostic instructions. | 2. | If the ISAT display reads "ACTIVE", clear all diagnostic trouble codes in the MIU, TCS and/or AF22 systems and drive the car to see whether any are generated afresh. If they are, continue as described below. With the ignition switched off, connect a BOB to the MOTRONIC control module and cable. Check that there is a signal of about 6.5 V and 40 Hz on pin 43 at idling speed. At 2500 rpm the signal should be about 6.5 V and 125 hz. If the signal is OK, the fault lies either in the leads connected to the MIU, TCS and/or AF22 control modules or in any of these systems. If there is no output signal on pin 43, it may be on account of a short circuit to ground/batt+ in any of the leads connected to the above systems. Rectify any faults. If there is no short circuit, turn to for further diagnostic instructions.