Indicator and Warning Lamps

Indicator and warning lamps

Automatic transmission




The transmission control module (TCM) activates the combined instrument panel warning lamp. The lamp lights up when the ignition is switched on and when driving if:
- The gear selector is in positions 3 or L
- Driving mode W (winter) has been selected.
The lamp flashes when the ignition is switched on and when driving if:
- The transmission control module (TCM) has detected a fault in the transmission. There are certain exceptions. See DTC table Automatic Transmission.
If the fault is intermittent the indicator and warning lamp will go out after the ignition has been switched on and off a certain number of times. The ignition may have to be switched on up to five times, depending on the diagnostic trouble code (DTC) that has been stored. For diagnostic trouble code (DTC) AT-235, High oil temperature, the lamp flashes only as long as the temperature of the oil exceeds +140°C.

Malfunction indicator lamp (MIL)




The malfunction indicator lamp (MIL) is activated if the engine management systems malfunction. These malfunctions can cause engine running problems and result in the engine failing to maintain required emission levels. In some markets where an on-board diagnostics system OBD II is a statutory requirement, the transmission control module (TCM) can also activate the malfunction indicator lamp (MIL). The transmission control module (TCM) sends a request to the engine control module (ECM) to activate the malfunction indicator lamp (MIL) if an emission-related transmission malfunction occurs. (The Motronic 4.4 engine control module (ECM) posts a diagnostic trouble code (DTC) when the transmission sends a malfunction indicator lamp (MIL) request.) The malfunction indicator lamp (MIL) lights when the following automatic transmission diagnostic trouble codes (DTCs) are stored:
- AT-121 Shift solenoid S1, short-circuit to ground
- AT-122 Shift solenoid S1, fault in the solenoid circuit
- AT-123 Line pressure solenoid STH, short-circuit to supply voltage
- AT-132 Control module, short-circuit in amplifier STH
- AT-213 Throttle position (TP) sensor signal, signal too high
- AT-221 Shift solenoid S2, short-circuit to ground
- AT-222 Shift solenoid S2, fault in solenoid circuit
- AT-223 Throttle position (TP) sensor signal, signal too low
- AT-232 Vehicle speed signal, signal missing
- AT-311 Transmission speed sensor, signal missing
- AT-313 Gear-shift position sensor, faulty signal
- AT-321, Gear 1, incorrect ratio
- AT-322, Gear 2, incorrect ratio
- AT-323, Gear 3, incorrect ratio
- AT-324, Gear 4, incorrect ratio
- AT-331 Lock-up solenoid SL, short-circuit to supply *)
- AT-332, Lock-up solenoid SL, break in circuit *)
- AT-333 Lock-up solenoid SL, short-circuit to supply *)
- AT-341 Lock-up slips or is disengaged *)
- EFI-412 Engine control module (ECM), memory fault *)
*) Applies to 1997 model year-
See also table, On Board Diagnostics II (OBD II) On Board Diagnostics II (OBD II).