Diagnostic Aids
WARNING: This page is about a different car, the 2004 GMC Sierra, 2004 GMC Cab & Chassis Sierra, 2004 Chevrolet Silverado, and 2004 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.
- Solenoids are sensitive to battery voltage spikes and poor ground connections. This condition may not be indicated with your scan tool, or with a DVOM.
- The installation of aftermarket devices such as remote starters may interfere with proper TCM voltage supply.
- A faulty ignition switch may cause improper voltage supply to the TCM.
- Power or ground corrosion may cause voltage variation.
- Voltage may vary by 0.5 volts based on the state of charge in the battery.
- PC solenoid A operates on 1,000 Hz and can be measured using a DMM. Refer to Measuring Frequency in Wiring Systems.