Headlight Switch: Mustang
- Ensure all bulbs and fuses are good before proceeding. Remove headlight switch. Refer to HEADLIGHT SWITCH R & I under REMOVAL & INSTALLATION. Test headlight switch positions for continuity. See Fig 1.
- Reconnect headlight switch. Using test light, backprobe connector between terminals B1 and body ground. If test light does not glow, repair open in Black/Orange wire from fusible link. See appropriate WIRING DIAGRAMS in this article.
- Using test light, backprobe connector between terminals B1 and "G" (ground). If test light does not glow, repair open in Black wire ground circuit.
- Using test light, backprobe connector between terminal B2 and body ground. If test light does not glow, repair open in Tan/White wire to fuse block fuse No. 4.
- Using jumper wire, connect terminals B1 and "H". If headlights do not operate, check for the following and repair as required:
- Open in Red/Yellow wiring to dimmer switch
- Faulty dimmer switch
- Open in high beam Light Green/Black wiring to both headlights
- Open in low beam Red/Black wiring to both headlights
- Open in ground circuit to headlights
- Using jumper wire, connect terminals B2 and "R". If rear lights and all parking lights do not come on, repair open in Brown wiring. If no problem exists in those circuits, repair ground circuit to rear lights.
- Circuit "R" also powers LCD illumination relay and panel dimming rheostat. If dimmer control does not vary panel brightness, repair open in Brown wire between headlight switch terminal "R" and dimmer control switch. Also check for blown fuse No. 13.
- Using jumper wire, connect terminals B2 and "I". If instrument panel does not come on fully bright, repair open in Light Brown/Red wiring.
Courtesy of FORD MOTORS CO.