What is the maximum allowable current draw for the windshield wiper motor?

The current draw at either the low-speed or high-speed terminal should not exceed 3.5 amperes during the Windshield Wiper Motor Current Draw Test.

How do I test the wiper motor ground wire?

With the windshield wiper switch set to HIGH, ground the wiper motor case to body ground. If the wiper motor then runs, repair the windshield wiper motor ground wire.

What resistance should be between circuits 993 and 589 with the wiper switch at LO?

With the WCM disconnected and the Wiper Switch at LO, resistance between circuits 993 and 589 should be 3.5K–4.5K ohms. If OK, replace the WCM; if not, check for a damaged Multi-function Switch.

What are the wire colors at wiper motor connectors C151 and C152?

C151: circuit 58 (W), 56 (DB/O), 61 (Y/R). C152: circuit 57 (BK), 28 (BK/PK), 65 (DG).

What should I check if the wipers will not turn off?

Check that wiper motor and WCM connectors are seated; with ignition in RUN and switch OFF, check continuity between circuits 28 and 56 and between 61 and chassis ground. If OK, check for a damaged wiper motor; if no continuity, check circuit 57 and measure resistance between circuits 589 and 993 (45K–50K ohms expected, otherwise replace WCM or repair wiring/switch).

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Ford Bronco Windshield Wiper Motor Testing & Diagnosis - WCM, C151/C152 Pinouts

Windshield wiper motor test procedure with wiring figure and diagnostic table

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Windshield wiper motor ground and current-draw test procedure with wiring diagram, connector pinout and diagnostic table.

AI caption October 2005 · Photo 156 of 277

This service document covers diagnosis and testing of a Ford windshield wiper motor system. It includes an illustrated Wiper Ground Wire Test and a Windshield Wiper Motor Current Draw Test using a Digital Volt-Ohmmeter (014-00407), with a labeled diagram showing tester lead hookups, battery connections, motor high/low speed terminals, motor ground terminal, and connectors C151 and C152. The current draw at both low- and high-speed terminals should not exceed 3.5 amperes. A detailed diagnostic table lists symptoms (wipers do not operate, LO speed inoperative, INT inoperative, wipers will not turn off, wipers will not park, washer inoperative), possible causes involving the Wiper Control Module (WCM), Multi-function switch, wiper motor, linkage, and washer pump, and step-by-step actions referencing circuit numbers (28, 56, 57, 58, 61, 65, 589, 590, 941, 993) and resistance specifications (e.g., 3.5K–4.5K ohms at LO, 10.5K–12K ohms for INT, 45K–50K ohms at OFF). Bottom pinout diagrams identify wire colors at wiper motor connectors C151 (58 W, 56 DB/O, 61 Y/R) and C152 (57 BK, 28 BK/PK, 65 DG). Readers can learn how to isolate faults among the wiper motor, WCM, switch, and wiring.

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Frequently asked questions

What is the maximum allowable current draw for the windshield wiper motor?: The current draw at either the low-speed or high-speed terminal should not exceed 3.5 amperes during the Windshield Wiper Motor Current Draw Test.
How do I test the wiper motor ground wire?: With the windshield wiper switch set to HIGH, ground the wiper motor case to body ground. If the wiper motor then runs, repair the windshield wiper motor ground wire.
What resistance should be between circuits 993 and 589 with the wiper switch at LO?: With the WCM disconnected and the Wiper Switch at LO, resistance between circuits 993 and 589 should be 3.5K–4.5K ohms. If OK, replace the WCM; if not, check for a damaged Multi-function Switch.
What are the wire colors at wiper motor connectors C151 and C152?: C151: circuit 58 (W), 56 (DB/O), 61 (Y/R). C152: circuit 57 (BK), 28 (BK/PK), 65 (DG).
What should I check if the wipers will not turn off?: Check that wiper motor and WCM connectors are seated; with ignition in RUN and switch OFF, check continuity between circuits 28 and 56 and between 61 and chassis ground. If OK, check for a damaged wiper motor; if no continuity, check circuit 57 and measure resistance between circuits 589 and 993 (45K–50K ohms expected, otherwise replace WCM or repair wiring/switch).