Buffer Power Testing & Diagnosis
WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 1991 GMC Pickup, 1991 GMC Cab & Chassis, 1991 GMC C3500 HD, 1991 Chevrolet Pickup, and 1991 Chevrolet Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:
Before testing BUFFER POWER, perform test for any symptoms found. See SPEEDOMETER/ODOMETER TESTING & DIAGNOSIS .
- Disconnect instrument cluster connector. Turn ignition on. Turn on cruise control (if equipped). Using a DVOM, check for 12 volts between ground and Pink/Black wire at cluster harness connector terminal A9. See Figure. If voltage reading is 12 volts, go to step 2. If voltage reading is less than 12 volts, check for blown GAGES fuse. If fuse is okay, check for open in Pink/Black wire.
- Check for 12 volts between ground and Brown wire at harness connector terminal B14. See Figure. If voltage reading is 12 volts, go to step 3. If voltage reading is less than 12 volts, check for blown BRAKE fuse. If fuse is okay, check for open in Brown wire.
- Check for 12 volts between Brown wire at connector terminal B14 and White wire at cluster harness connector terminal B15. If voltage reading is 12 volts, go to step 4. If voltage reading is less than 12 volts, check for open in White wire.
- Check for 12 volts between Brown wire at connector terminal B14 and Black wire at harness connector terminal B1. If voltage reading is 12 volts, check for problem in VSS circuit. See VEHICLE SPEED SENSOR . If voltage reading is less than 12 volts, repair open in Black wire.