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.
Inspect the batteries for proper voltage.
Inspect the charging system for proper operation.
You may have to drive the vehicle in order to experience a condition.
Inspect for the presence of aftermarket accessories, such as remote starters, etc. Depending on how these aftermarket accessories are installed, they may interfere with the required voltage for proper operation of the transmission.

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. With the scan tool, monitor the ignition signal voltage in the TCM data list. Is the voltage greater than the specified value?	10.5 V	Go to Step 4	Go to Step 3
3	Test the ignition feed circuit to the TCM for high resistance or an open. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition?	-	Go to Step 7	Go to Step 5
4	Inspect for poor connections at the TCM. Refer to Testing for Intermittent Conditions and Poor Connections . If you find a poor connection, repair the condition, as necessary. Refer to Wiring Repairs . Did you find and correct the condition?	-	Go to Step 7	Go to Step 6
5	Repair the ignition feed circuit to the TCM for an open or a short to ground. Refer to Wiring Repairs . Did you complete the repair?	-	Go to Step 7	-
6	IMPORTANT: In most cases the TCM is not at fault. Attempt swapping with a known good TCM prior to replacing the TCM. Replace the TCM. Refer to Transmission Control Module Replacement .Did you complete the replacement?	-	Go to Step 6	-
7	Perform the following procedure in order to verify the repair: Clear the DTC. Using the scan tool, monitor TCM voltage. Select Specific DTC. Enter DTC P0562. Has the test run and passed?	-	System OK	Go to Step 1