Installing headlamp relays on a 1989

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By Nick Chrimes, BaySHO Performance

1989...the first pic shows a multifunction switch connector. The second pic shows the corresponding part inside the MF switch. This knocked out the headlamps. IMG 20191203 144224770 (1024x836).jpg IMG 20191203 170245867 (816x1024).jpg

The circuit overheated somehow. Wasn’t because the bulbs were too powerful. This has been a somewhat rare problem with the 89s. The MF switch was redesigned for 1990 on, and has never been a problem since. Burnt area around the R/Y wire comes from the main light switch and the autolamp switch. The O/BK wire goes to the headlight low beam. The solution is to install relays in the engine compartment so that the power for the headlights comes directly from the battery as opposed to through the MF switch. Will not only prevent the switch from overheating but can allow the 9004 bulbs to be upgraded from 55W to 85W. The only downside is that the LAMP OUT bulb is lit on low beam, but goes out on high beam.


Power from the starter solenoid, ground on the fender, LG/BK high and R/BK low beam wires located, relays installed on the cruise control servo mounting bracket:

IMG 20191207 113633060 (768x1024).jpg IMG 20191207 114027757 HDR (1024x768).jpg IMG 20191207 141619871 HDR (1024x768).jpg Relay schematic.jpg

Parts required:

SPST Headlamp Circuit Power Relay (2 Novita) RL44 $15 Autozone

Terminal Rings (2 Dorman) 85411 $1 Autozone

Female Spade Connectors (8 Dorman) 84151 $6 Autozone

Wire, Wire Sleeve, Insulation Tape, Mounting bolts / nuts $5

Total Parts $27


Install Headlamp Relays 3.0 hours Actual 8+ hours