Allison 1000 & 2000 Gen 5 Fault Code:P0701 Transmission Control System – Performance

Description

CIRCUIT DESCRIPTION:
The TCM monitors the status of the pressure switches at start-up to detect the presence of hydraulic pressure.

ACTION TAKEN WHEN THE DTC SETS:
1. The CHECK TRANS light is not illuminated (non-OBD II strategy).
2. The TCM forces Variable Modulated Main off.
3. A latched range inhibit is commanded. Operator is required to reselect range.
4. DTC is stored in the TCM history.

CONDITIONS FOR CLEARING THE DTC:
The diagnostic tool may be used to clear the DTC from the TCM history. The TCM automatically clears the DTC from the TCM history if the vehicle completes 40 warm-up cycles without the DTC recurring.

DIAGNOSTIC AIDS:
1. DTC P0701 may be logged if a forward or reverse range is selected immediately after the engine is started and before the TCM detects pressure at the switches.
2. A plugged control main filter may cause this DTC to set.
3. A cracked internal suction filter tube or damaged tube seal may cause this DTC to set.
4. A stuck lube regulator valve (located in the front support) may cause this DTC to set. A high static oil level with the vehicle running is often a good indication of this complaint. Often pressure switch DTCs are set in this scenario.
5. You may have to drive the vehicle in order to experience a fault.
6. Use of a shallow sump filter in a deep sump pan can also set this DTC. Inspect for correct filter size.