Allison 1000 & 2000 Gen 5 Fault Code:P0882 TCM Power Input Signal – Low

CIRCUIT DESCRIPTION:
The TCM requires input battery voltage which originates direct from the vehicle battery and runs through a 10 amp fuse to TCM pins 10 (wire 110) and 70 (wire 170).

DTC P0882 sets when the TCM detects the following:
Battery direct voltage is detected below 9 volts for a calibrated time.

ACTION TAKEN WHEN THE DTC SETS:
1. Hydraulic default is commanded. Shift selector position and hydraulic state of logic valves determine range.
2. The CHECK TRANS light illuminates (non-OBD II strategy).
3. The TCM forces Variable Modulated Main off.
4. The TCM inhibits Torque Converter Clutch (TCC) engagement.

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:
The following procedures are not documented in any OEM procedures or in any OEM Troubleshooting or Service information and should not be used as a method to diagnose any transmission DTCs, function, or shift quality concern:

1. Back-probing any connections used for transmission features or functions may damage and/or unlock terminals from the back-probed connector creating permanent or intermittent shorts and/or open circuits. If possible, use the J-39700 Breakout Box, the appropriate harness adapters, and appropriate magnetic overlays to troubleshoot the vehicle.

2. Load-testing any transmission-related circuits with any other electrical devices such as vehicle lamps or relays, especially with the TCM connected to the harness. Use J-39700 Breakout Box and appropriate harnesses with the diagnostic tool to monitor the circuit performance in question unless otherwise specified in the various Troubleshooting information.

3. Piercing a wire to check for voltages, shorts-to-grounds or other wires anywhere in the circuit but especially at the TCM. This creates a leak path for moisture and damages the wire and insulation.

4. Vehicle charging system failure may cause this DTC to set under certain circumstances

5. A defective vehicle battery may induce this DTC. Test the vehicle battery to verify proper voltage and load capacity.

Inspect the wiring for poor electrical connections at the TCM. Look for the following conditions:
1. A bent terminal.
2. A backed-out terminal.
3. A damaged terminal.
4. Poor terminal tension
5. A chafed wire.
6. A broken wire inside the insulation.

When diagnosing for an intermittent short or open, massage the wiring harness while watching the test equipment for a change.