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Home >> GMC >> 1999 >> Forward Control 7.4 B >> Repair and Diagnosis >> Accessories & Equipment >> Wiper/Washer Systems >> Wiper System And Washer System >> System Tests >> Test 1: Wipers All Modes Inoperative

Test 1: Wipers All Modes Inoperative

  1. Turn ignition switch to RUN position. Connect test light between ground and wiper/washer provision connector terminal "E" (Yellow wire). If test light is on, go to next step. If test light is off, repair open in Yellow wire between WIPER fuse (25-amp) in instrument panel fuse block and wiper/washer provision connector terminal "E". See WIRING DIAGRAMS  .
  2. Using DVOM connected to battery voltage, backprobe pulse wiper control module terminal "D" (Black wire). See Fig 1 . Pulse wiper control module is tie strapped to engine wiring harness, under steering column support. If reading is 10 volts or more, go to next step. If reading is less than 10 volts, repair open in Black wire between pulse wiper control module terminal "D" and ground connection G200. Ground connection G200 is located at top front of steering column support plate. See WIRING DIAGRAMS  .
  3. Using DVOM connected to battery voltage, backprobe wiper/washer switch pigtail connector terminal "D" (Black wire) at base of steering column. If reading is less than 10 volts, replace pulse wiper control module. See PULSE WIPER CONTROL MODULE  under REMOVAL & INSTALLATION. If reading is 10 volts or more, replace wiper/washer switch. See WIPER SWITCH  under REMOVAL & INSTALLATION.
Fig 1: Identifying Pulse Wiper Control Module Connector Terminals
G99C02284