Trouble Code Conditions

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Trouble Code Conditions
- The transmission control module (TCM) calculates the ratio between the transmission input speed and the vehicle speed. There is a specific ratio for each gear. Diagnostic trouble codes (DTCs) AT-321, AT-322 or AT-323 are stored if the transmission control module registers a deviation of greater than 10% in the ratios of 1st, 2nd or 3rd gears respectively.

Substitute value(s)
- The transmission control module limp-home program has been initiated.

Possible source(s)
- Interference with or faulty transmission speed sensor signal.
- Interference with or errors in the speed signal from the combined instrument panel.
- Contact resistance in the Solenoid S1 and S2 circuits.
- Gear-shift position sensor incorrectly adjusted.
- Defective gear-shift position sensor.
- Transmission oil level too low.
- Mechanical fault in the transmission. Worn components in the transmission causing slippage or reduced system pressure.
- Defective power ground.
- Short-circuit to ground in transmission speed sensor signal cable (-).

Fault symptom(s)
- The combined instrument panel warning lamp flashes.
- Mechanical malfunction. Faults are usually indicated by noise or other obvious function problems.
- Deterioration in performance because the transmission control module prevents activation of the solenoids, this stops gear-shifting. The transmission only operates in 3rd gear in positions 3 and L, 4th gearing position D and reverse in position R. Shifting can only be carried out manually between 3rd, 4th, and reverse gears.
- No system pressure solenoid STH control resulting in constant maximum system pressure leading to harsher shifting and gear meshing.
- No lock-up function.

NOTE: The Motronic 4.4 engine control module (ECM) posts a diagnostic trouble code when the transmission sends a malfunction indicator lamp (MIL) request. Erase this diagnostic trouble code in the Motronic engine control module when the transmission fault has been repaired.

- Start fault-tracing.Incorrect Gear Ratio