Circuit/System Testing
WARNING: This page does not describe the selected car, but rather 7 other vehicles, including the 2008 GMC Yukon XL, 2008 GMC Yukon, 2008 Chevrolet Tahoe, 2008 Chevrolet Suburban, and 2008 Cadillac Escalade EXT. However, it is still accessible from the selected car via links, so may be relevant.
- Turn the ignition ON.
- Observe the transmission ISS/OSS supply voltage circuit status on the scan tool. The parameter should display OK.
- If the parameter does not display OK, disconnect the ISS/OSS connector from the control solenoid (w/body and TCM) valve assembly and recheck the scan tool display.
- If the transmission ISS/OSS supply voltage circuit status still displays OK, visually inspect the OSS, harness, connector, the control solenoid (w/body and TCM) valve assembly pins for metallic debris and output shaft machined surface for damage or misalignment.
- Repair or replace the damaged components.
- Perform the Control Solenoid Valve and Transmission Control Module Assembly Input Shaft Speed/Output Shaft Speed Input Test
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- The scan tool Transmission OSS parameter should display 100-400 RPM.
- If the Transmission OSS parameter is between 100-400 RPM, replace the ISS/OSS assembly.
- If no OSS RPM is displayed or the parameter is out of range, replace the control solenoid (w/body and TCM) valve assembly.