Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSGMC1999FORWARD CONTROL 5.7 R, AUTOMATICREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 236 (WIPER SYSTEM & WASHER SYSTEM)SYMPTOM TESTSTEST B: WASHERS INOPERATIVE
1999 GMC Forward Control 5.7 R, Automatic
Test B: Washers Inoperative
1999 GMC Forward Control 5.7 R, AutomaticSECTION Test B: Washers Inoperative
WARNING: This page is about a different car, the 2002 GMC Savana and 2002 Chevrolet Chevy Express. However, it is still accessible from the selected car via links, so may be relevant.
- If wiper/washer system description and operation, and preliminary inspection has been reviewed, and necessary inspections have been performed, go to next step. See DESCRIPTION , OPERATION & PRELIMINARY INSPECTION under TROUBLE SHOOTING.
- Turn ignition switch to RUN position. Press windshield washer switch. If washers do not operate normally, go to next step. If washers operate normally, concern my be intermittent. For aid in diagnosing intermittents, see PRELIMINARY INSPECTION under TROUBLE SHOOTING.
- Disconnect windshield washer pump motor 2-pin harness connector. Windshield washer pump motor is located in washer reservoir. Turn ignition switch to RUN position. Connect test light between windshield wiper motor harness connector terminals "A" (Red wire) and "B" (Black wire). Press windshield washer switch. If test light does not illuminate, go to next step. If test light illuminates, go to step 7 .
- Check for open or high resistance in washer pump control circuit, Red wire between wiper motor harness connector "E" and washer pump motor harness connector "A". See WIRING DIAGRAMS . Check for open or high resistance in washer pump ground circuit, Black wire between ground and washer pump motor harness connector "B". Ground point is located behind driver's side kick panel. If no problem exists, go to next step. If problem exists, repair as necessary and go to step 14 .
- Disconnect windshield wiper motor 6-pin harness connector. Windshield wiper motor is located in cowling at left front of engine compartment. Using a test light connected to ground, probe windshield wiper motor harness connector "D" (Brown wire), windshield wiper switch pulse delay signal circuit. See Fig 1 . Turn ignition switch to RUN position. If test light does not illuminate, go to next step. If test light illuminates, go to step 14 .
- Connect test lamp from low signal circuit terminal in wiper motor harness connector to a good ground. Turn ignition ON. Press the windshield washer switch. If test lamp does not illuminate, go to next step. If test lamp illuminates, go to step 12 .
- Check for open or high resistance in windshield wiper switch pulse delay signal circuit, Gray wire (changes to Brown at wiper motor) between windshield wiper switch harness connector terminal No. 96 and windshield wiper motor harness connector terminal "D". See WIRING DIAGRAMS . If problem exists, repair as necessary and go to step 14 . If no problem exists, go to next step.
- Inspect windshield wiper/washer switch for poor connections. If no condition is found, go to next step. If condition is found, repair as necessary and go to step 14 .
- Replace windshield wiper/washer switch. See WINDSHIELD WIPER/WASHER SWITCH under REMOVAL & INSTALLATION. After repairs are made, go to step 14 .
- Inspect windshield washer pump for poor connections. If no condition is found, go to next step. If condition is found, repair as necessary and go to step 14 .
- Replace washer pump motor. See WASHER RESERVOIR & PUMP MOTOR under REMOVAL & INSTALLATION. After repairs are made, go to step 14 .
- Inspect windshield wiper motor for poor connections. If no condition is found, go to next step. If condition is found, repair as necessary and go to step 14 .
- Replace wiper motor cover. See WIPER MOTOR COVER under REMOVAL & INSTALLATION. After repairs are made, go to next step.
- Operate wiper/washer system to verify repairs. If system operates normally, testing is complete. If system does not operate normally, go to step 3 .
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.