GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2002 🢒 GMC C Sierra - 2WD 🢒 Transmission/Transaxle 🢒 Automatic Transmission - Allison 🢒 DTC P0880

Circuit Description

DTC P0880 will set if an abnormal power-down sequence has occurred. This condition means the transmission control module (TCM) has lost battery positive voltage circuit, supply voltage, before it has finished saving information from that drive cycle. This process is usually completed in less than 10 seconds.

DTC P0880 is a type C DTC.

Conditions for Running the DTC
    • The components are powered and ignition voltage is greater than 9.0 volts and less than 18 volts.
    • Loss of TCM supply voltage before drive cycle data is saved.

Conditions for Setting the DTC

DTC P0880 sets during the next ignition cycle if the TCM loses TCM supply voltage less than 10 seconds after the ignition voltage has been turned off.

Action Taken When the DTC Sets
    • The TCM does not illuminate the malfunction indicator lamp (MIL).
    • DTC P0880 will be stored in TCM history.
    • Loss of adaptive information for drive cycle. Revert to previous adaptive settings.
    • The TCM inhibits torque converter clutch (TCC) engagement.

Conditions for Clearing the DTC

A scan tool can clear the code from TCM history. The TCM automatically clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without failure.

Diagnostic Aids
    • Inspect the wiring for poor electrical connections at the TCM. Inspect for the following conditions:
       - A bent terminal
       - A backed-out terminal
       - A damaged terminal
       - Poor terminal tension
       - A chafed wire
       - 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.
    • You may have to drive the vehicle in order to experience a condition.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. This step tests the system voltage.

    2.

  2. This step tests the vehicle charging system.

    3.

  3. This step tests the wiring harness for opens or shorts.

Step

Action

Value

Yes

No

Schematic Reference: Automatic Transmission Controls Schematics

1

Did you perform the Diagnostic System Check - Automatic Transmission?

--

Go to Step 2

Go to Diagnostic System Check - Automatic Transmission

2

  1. Install the scan tool.
  2. Turn ON the ignition, with the engine OFF.

    3. Important: Before clearing the DTC, use the scan tool in order to record the Freeze Frame and Failure Records for reference. The Clear Info function will erase the data.

  3. Record the DTC Freeze Frame and Failure Records.
  4. Clear the DTC.

    5. Important: If other DTCs are present, refer to the applicable diagnostic tables before continuing.

  5. Using a DMM, measure and record the voltage at the battery terminals.

Is voltage within the specified value?

B+

Go to Step 3

Go to Battery Inspection/Test in Engine Electrical

3

Start the engine and warm to normal operating temperature.

Is the Alternator/Check Engine lamp ON?

--

Go to Charging System Test in Engine Electrical

Go to Step 4

4

  1. Increase the engine speed to 1,000-1,500 RPM.
  2. Observe the system voltage on the scan tool.

Is voltage within the specified range?

13-15 V

Go to Step 5

Go to Charging System Test in Engine Electrical

5

  1. Turn the ignition OFF.
  2. Disconnect the TCM connector C1 (GRAY).
  3. Install the J 39700 breakout box and the J 43799 breakout box adapter. Additional DTCs may set.
  4. Turn the ignition ON, with the engine OFF.
  5. Using a DMM, measure the voltage between connector C1 terminal 1 and terminal 2, with the ignition ON.
  6. Measure the voltage between connector C1 terminal 1 and terminal 3, with the ignition OFF.

Is voltage within the specified value of B+ voltage?

0.5 V

Go to Step 6

Go to Step 7

6
  1. Inspect the transmission wiring harness assembly.
  2. Repair the transmission wiring harness assembly.

    3. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 8

--

7

Important: In most cases, the TCM is not at fault. Investigate thoroughly before replacing the TCM.

Replace the TCM. Refer to Transmission Control Module Replacement .

Did you complete the replacement?

--

Go to Step 8

--

8

Perform the following procedure in order to verify the repair:

  1. Clear the DTC.
  2. Using the scan tool, monitor system voltage.
  3. Select Specific DTC.
  4. Enter DTC P0880.

Has the test run and passed?

--

System OK

Go to Step 1