Control Module Output Test
- See TESTING PRECAUTIONS and PRELIMINARY CHECKS
before beginning test. Turn ignition off for 5 seconds. Start engine and run to warm. With gear selector in Park, press DE-ICE key. Disconnect WCM connector. See Figure
or Figure
. Connect 10 Amp fused jumper wire between terminals A6 and B1 of WCM connector. See Fig 1
.CAUTION: DO NOT leave jumper connected for more than 4 minutes.NOTE: Figure 6 is Courtesy of General Motors Corp.
- If WPM clicks, go to step 3). If power module does not click, disconnect fused jumper and check fuse. If fuse is blown, check for short between WCM and WPM (Yellow/Black wire). If fuse is not blown, check for open circuit in Yellow/Black wire. Also check Black/White wire between WCM and isolated ground junction box, located behind battery, for open or high resistance. If all tests are okay, replace WPM.
- Reconnect fused jumper wire as in step 1). Measure voltage between terminals "B" and "C" at harness half of windshield connector. See Figure . If voltage is greater than 50 volts, ensure terminals in both halves of windshield connector are making contact. Repeat WINDSHIELD RESISTANCE TEST under PRELIMINARY TEST . Ensure symptom still exists. If voltage is lower than 50 volts, recheck connector terminal contact. Check for open circuit in Red/Black and Black/White wires between windshield and WPM. If okay, go to ALTERNATOR OUTPUT TEST.