Conditions for Clearing the DTC

WARNING: This page is about a different car, the 2007 GMC Yukon XL and 2007 Chevrolet Suburban. However, it is still accessible from the selected car via links, so may be relevant.

The ECM turns OFF the MIL after the third consecutive drive trip in which the TCM does not send a MIL illumination request.
A scan tool can clear the DTC.
The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without an emission related diagnostic fault occurring.
The TCM cancels the default actions when the ignition is OFF long enough in order to power down the TCM.

DTC P0977

Step	Action	Value	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 ECM and TCM Freeze Frame and Failure Records. Using the Clear Info function erases the Freeze Frame and Failure Records from the ECM and TCM. Record the DTC Freeze Frame and Failure Records. With a scan tool, command the 2-3 Sol. ON. Does the 2-3 Sol. CKT status parameter display OK?	-	Go to Testing for Intermittent Conditions and Poor Connections	Go to Step 3
3	Turn OFF the ignition. Disconnect the automatic transmission (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. Turn ON the ignition, with the engine OFF. Using the J 35616 GM-approved terminal test kit, connect a test lamp from the 2-3 SS valve control circuit of the J 44152 to ground. See Special Tools . Refer to Automatic Transmission Inline 20-Way Connector End View .Does the test lamp illuminate?	-	Go to Step 6	Go to Step 4
4	Install the J 44152 on the transmission side of the AT inline 20-way connector. Using the DMM and the J 35616 , measure the resistance between the ignition voltage and the 2-3 SS valve control circuits of the J 44152 . Refer to Automatic Transmission Inline 20-Way Connector End View .Does the resistance measure less than the specified value?	20 Ω	Go to Step 5	Go to Step 7
5	Disconnect the AT internal wiring harness from the 2-3 SS valve. Measure the resistance of the 2-3 SS valve. Does the resistance measure less than the specified value?	20 Ω	Go to Step 8	Go to Step 7
6	Test the control circuit of the 2-3 SS valve for a short to voltage between the TCM and the AT inline 20-way connector. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition?	-	Go to Step 10	Go to Step 9
7	Replace the AT internal wiring harness. Refer to Valve Body and Pressure Switch Replacement . Did you complete the replacement?	-	Go to Step 10	-
8	Replace the 2-3 SS valve. Refer to Valve Body and Pressure Switch Replacement . Did you complete the replacement?	-	Go to Step 10	-
9	Replace the TCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement?	-	Go to Step 10	-
10	Perform the following procedure in order to verify the repair: Select DTC. Select Clear Info. Drive the vehicle in D4 and ensure the following conditions are met: The TCM commands the 2-3 SS valve ON and the 2-3 Sol. CKT status parameter displays OK. The TCM commands the 2-3 SS valve OFF and the 2-3 Sol. CKT status parameter displays OK. All conditions are met for 4.3 seconds. Select Specific DTC. Enter DTC P0977. Has the test run and passed?	-	Go to Step 11	Go to Step 2
11	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