Allison 1000 & 2000 Gen 4 Fault Codes: P2810 Solenoid G Electrical

CIRCUIT DESCRIPTION:
Solenoid G is a normally closed (N/C) solenoid used to modulate the transmission main pressure schedule. The TCM commands the G solenoid ON when specific transmission and engine conditions are met. When G solenoid is applied, pressure is routed to the main regulator valve. This in turn reduces the main pressure schedule and improves the volume of oil sent through the overage circuit. By modulating main pressure, cooler flow can be increased, allowing improved cooling and reduced pump noise.

CONDITIONS FOR RUNNING THE DTC:
1. The components are powered and ignition voltage is greater than 9V and less than 18V (12V TCM) or greater than 18V and less than 32V (24V TCM).
2. TCM initialization is in process or engine speed is greater than 200 rpm and less than 7500 rpm for 5 seconds.
3. The TCM must autodetect G solenoid for this test to run.

CONDITIONS FOR SETTING THE DTC:
DTC P2810 is set when the TCM detects an open circuit, short to ground or short to power at G solenoid circuit for more than 2 seconds.

ACTION TAKEN WHEN THE DTC SETS:
When DTC P2810 is active, the following conditions will occur:
1. DTC P2810 is stored in TCM history.
2. The CHECK TRANS light illuminates.

CONDITIONS FOR CLEARING THE DTC/CHECK TRANS LIGHT:
A scan tool may be used to clear the code from the TCM history. The TCM automatically clears the DTC from the TCM history if the vehicle completes 40 warm-up cycles without failure.

DIAGNOSTIC AIDS:
When this code is set there will be a noticeable reduction of engine performance.

An intermittent circuit condition may allow this DTC to set. Make sure you check for the following conditions at the OEM harness first and then at the transmission internal harness.

Inspect the wiring for poor electrical connections at the TCM connector and the transmission main connector. 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.
7. Inspect OEM wiring harness routing, looking for possible contact points where chafing could occur. Moving parts on the vehicle could be contacting the harness. Check for contact at the parking brake drum, suspension components, transmission shift linkage etc.
8. Inspect the internal transmission wiring harness for possible contact areas where chafing may occur.

When diagnosing for an intermittent short or open, massage the wiring harness while watching the test equipment for a change. It may be necessary to check for shorting to ground at individual wires within a harness to isolate an intermittent condition. Refer to Wire Check information.

You may have to drive the vehicle in order to experience a fault. Use the data obtained from failure records to determine transmission range and/or certain vehicle operating variables such as temperature, run time, etc. This data can be useful in reproducing the failure mode where DTC was set.

If the DTC appears to be temperature related, suspect a defective G solenoid. It is possible for a solenoid to be temperature sensitive causing resistance values to fluctuate. This may cause an intermittent DTC to be set.