Allison 3000 & 4000 Gen 4 Fault Code: P0883 TCM Power Input Signal High

DIAGNOSTIC RESPONSE:
None

CIRCUIT DESCRIPTION:
The Transmission Control Module (TCM) requires direct battery voltage input to operate. This test monitors for high battery voltage to the TCM on terminals 10 and 70.

NOTE: The TCM battery power signal must be provided through a 10a or 15A fuse, or a manually-reset circuit breaker.

CONDITIONS FOR RUNNING THE DTC:
1. Engine speed above 450 rpm for at least 30 seconds.
2. DTC test runs at 0.025 second intervals.

CONDITIONS FOR SETTING THE DTC:
DTC P0883 sets:
1. For a 12V TCM, battery voltage exceeds 18 volts after engine runtime over 1.5 seconds.
2. For a 24V TCM, battery voltage exceeds 32 volts after engine runtime over 1.5 seconds.

ACTION TAKEN WHEN THE DTC SETS:
1. The TCM illuminates the CHECK TRANS light.
2. Solenoids OFF (Hydraulic default).
3. TCC solenoid OFF.
4. Main Mod Solenoid OFF.

CONDITIONS FOR CLEARING THE DTC:
Use the diagnostic tool 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. A defective vehicle battery may allow this DTC to set. Test all vehicle batteries to OEM specifications for proper voltage and load capacity.
2. A defective vehicle charging system may cause this DTC. Test the charging system to all OEM specifications.
3. Over-voltage from battery charger.
4. Battery voltage is available on the diagnostic tool Data Monitor grid. Prior to ‘Connect’ for the diagnostic tool, check the ‘Troubleshoot Specific Problem’ box under “Connection Options” and then check the ‘Sensor, Voltage, Ohms, and Counts Data’ box.
5. Broken or defective connector assemblies allowing pushed back pins to short together.
6. Unlocked connectors, missing seal plugs allowing moisture in connectors.
7. Defective TCM may cause this code.

Review applicable information in Control System and Transmission Specifications to find additional circuit specifications, system and connector diagrams, and troubleshooting tips.