Diagnostic Aids

WARNING: This page is about a different car, the 2008 GMC Sierra, 2008 GMC Cab & Chassis Sierra, 2008 Chevrolet Silverado, and 2008 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

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.
DTC P0964 set in combination with DTC P0972, P0975 and P0978 may indicate an open in the HSD2 circuit.

Step	Action	Value	Yes	No
Schematic Reference: Automatic Transmission Controls Schematics
1	Did you perform the Diagnostic System Check - Vehicle?	-	Go to Step 2	Go to Diagnostic System Check - Vehicle
2	Install the 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 for reference. The Clear Info function will erase the data. Record the DTC Freeze Frame and Failure Records. Clear the DTC. Using the scan tool, measure ignition voltage. Is voltage within the specified value?	9-18 V	Go to Step 3	Go to DTC P0562 for low voltage or DTC P0563 for high voltage
3	Turn the ignition OFF. Disconnect the 80-way connector at the TCM. Install the J 39700 breakout box, the J-47275 breakout box adapter and the J 47275-1 magnetic overlay. Do not reconnect the TCM. Using the DMM, measure resistance at terminals 36 and 71. Is the resistance reading within the specified value?	5.05 Ω at 20°C (68°F)	Go to Testing for Intermittent Conditions and Poor Connections	Go to Step 4
4	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 transmission side of the AT inline 20-way connector. Using the DMM and the J 35616 GM terminal test kit, measure the resistance between terminals N and P of the J 44152 . Refer to Inline Harness Connector End Views . Is the resistance within the specified value?	5.05 Ω at 20°C (68°F)	Go to Step 6	Go to Step 5
5	Remove the transmission oil pan. Refer to Oil Pan Replacement . Remove the AT internal wiring harness at the PCS2 connector. Using the DMM, measure the resistance of the PCS2. Is the solenoid resistance within the specified value?	5.05 Ω at 20°C (68°F)	Go to Step 7	Go to Step 8
6	Test the PCS2 circuit between the TCM and the AT inline 20-way connector for an open condition. Refer to Testing for Continuity . Did you find and correct the condition?	-	Go to Step 10	Go to Step 9
7	Replace the AT internal wiring harness. Refer to Wiring Harness Replacement . Did you complete the replacement?	-	Go to Step 10	-
8	Replace the PCS2. Refer to Control Valve Solenoid Replacement (SS1, SS2, SS3, TCC, and MAIN MOD) or Control Valve Solenoid Replacement (PCS1 and PCS2) . Did you complete the replacement?	-	Go to Step 10	-
9	IMPORTANT: In most cases, the TCM is not at fault. Investigate thoroughly before replacing the TCM. 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: Clear the DTC. Drive the vehicle under normal operating conditions. Select Specific DTC. Enter DTC P0964. 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