Test Description

WARNING: This page is about a different variant/trim than selected.

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

3: This step tests the PCM and the wiring to the transmission.
5: This step verifies that the circuit has the correct resistance.

DTC P0977

Step	Action	Values	Yes	No
1	Did you perform the Diagnostic System Check - Vehicle?	-	Go to Step 2	Go to Diagnostic System Check - Vehicle
2	Install a scan tool. Turn ON the ignition, with the engine OFF. IMPORTANT: Before clearing the DTC, use the scan tool in order to record the Freeze Frame and Failure Records. Using the Clear Info function erases the Freeze Frame and Failure Records from the powertrain control module (PCM). Record the DTC Freeze Frame and Failure Records. Clear the DTC. Select 2-3 Sol. Short to Volts on the scan tool. Drive the vehicle in D4. When 3rd or 4th gear is commanded, does the scan tool display indicate a short to voltage?	-	Go to Step 3	Go to Testing for Intermittent Conditions and Poor Connections
3	Turn OFF the ignition. Disconnect the AT inline 20-way connector. Additional DTCs may set. Install the J 44152 Jumper Harness (20 pins) on the engine side of the AT inline 20-way connector. See Special Tools . Using the J 35616 GM Terminal Test Kit, connect a test lamp between the 2-3 shift solenoid (SS) valve control circuit of the J 44152 and ground. See Special Tools . Refer to Automatic Transmission Inline 20-Way Connector End View . Turn ON the ignition, with the engine OFF. Is the test lamp ON?	-	Go to Step 4	Go to Step 5
4	Test the control circuit of the 2-3 SS valve for a short to voltage between the PCM and the AT inline 20-way connector. Refer to Testing for a Short to Voltage and Wiring Repairs . Did you find and correct the condition?	-	Go to Step 11	Go to Step 10
5	Turn OFF the ignition. Disconnect the J 44152 from the engine side of the AT inline 20-way connector. See Special Tools . Install the J 44152 on the transmission side of the AT inline 20-way connector. See Special Tools . Using the DMM and the J 35616 , measure the resistance between the 2-3 SS valve ignition voltage and control circuits of the J 44152 . See Special Tools . Refer to Automatic Transmission Inline 20-Way Connector End View .Does the resistance measure within the specified range?	20-40 Ω	Go to Step 7	Go to Step 6
6	Leave the DMM test leads connected. Disconnect the 2-3 SS valve from the automatic transmission wiring harness. Does the resistance measure less than the specified value?	100 Ω	Go to Step 8	Go to Step 9
7	Measure the resistance between the 2-3 SS valve control circuit and all other terminals, except the 2-3 SS valve ignition voltage circuit, of the J 44152 . See Special Tools . Refer to Automatic Transmission Inline 20-Way Connector End View . Does the resistance measure less than the specified value?	100 Ω	Go to Step 8	Go to Testing for Intermittent Conditions and Poor Connections
8	Replace the automatic transmission wiring harness. Refer to Valve Body and Pressure Switch Replacement . Did you complete the replacement?	-	Go to Step 11	-
9	Replace the 2-3 SS valve. Refer to Valve Body and Pressure Switch Replacement . Did you complete the replacement?	-	Go to Step 11	-
10	Replace the PCM. Refer to Control Module References . Did you complete the replacement?	-	Go to Step 11	-
11	Perform the following procedure in order to verify the repair: Select DTC. Select Clear Info. Operate the vehicle under the following conditions: Drive the vehicle in D4. Allow the transmission to obtain a 3-4 upshift. Select Specific DTC. Enter DTC P0977. Has the test run and passed?	-	Go to Step 12	Go to Step 2
12	With the scan tool, observe the stored information, capture info. and DTC info. Does the scan tool display any DTCs that you have not diagnosed?	-	Go to Diagnostic Trouble Code (DTC) List - Vehicle	System OK