Circuit/System Testing

WARNING: This page is about a different car, the 2008 GMC Yukon XL, 2008 GMC Yukon, 2008 Chevrolet Tahoe, 2008 Chevrolet Suburban, and 2008 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.

Perform the Transmission Fluid Check .
- Correct the transmission fluid level if the fluid is not at the proper level.
Using the scan tool, clear the DTC. If DTC P0742 was set, operate the vehicle in D at 72 km/h (45 mph) with the throttle greater than 15 percent, allowing the transmission to shift through all gears. Use the scan tool to command the TCC ON. Observe the TCC Slip Speed parameter on the scan tool. The TCC Slip Speed should be between -20 to 20 RPM.
- If the TCC Slip Speed is between 130-1,500 RPM for greater than 2.5 seconds, inspect the following components and repair or replace as necessary:
  - Clogged exhaust orifice in the TCC solenoid valve
  - Converter clutch apply valve stuck in the apply position
  - Misaligned or damaged valve body gasket
  - Restricted release passage
  - Restricted transmission cooler line
Using the scan tool, clear the DTC. If DTC P0752 or P0757 is set, drive the vehicle in D and ensure that the TCM commands all gears. The ratios should match the commanded gear for all gears.

If the gear ratios do not match the commanded gear, inspect the following and repair or replace as necessary:

P0752, P0757

An internal malfunction
Damaged seals on the shift solenoid valve-Refer to Shift Solenoid Leak Test .