Electrical Another burned up dimmer switch
TSB8C
Old Time Jeeper
- Posts
- 1,027
- Featured
- 11
- Media
- 26
- Resources
- 1
- Solutions
- 24
- Thanks
- 536
- Location
- Cut-n-Shoot, TX
- Vehicle(s)
- 1984 CJ7, 420 HP "ZZ6 EFI" Crate engine, 700R4, D300, Dana30 front, Dana489 rear, 4.56 gears, 4" lift
This seems a common issue for CJ's - the floor mounted dimmer switch burns up and/or the socket along with it. My headlights (prior to LED conversion) quit working and tracing the wiring I discovered that the dimmer switch had a burned center prong and the socket connector had partially melted. Now we all know that these old CJ's had some inferior wiring for some circuits, and this appears to be one of those areas. So I decided to do a mod to this wiring that removed the high current draw of the headlight bulbs away from this headlight switch and dimmer switch wiring and instead move it to some relays in a separate fuse box. Now the headlight switch and dimmer switch merely activate the low current draw relays instead. Now I later upgraded to LED lights (headlights and turn signals both), so this may be a moot point since those draw lower current. But I still like the mod and thought others might as well.
First off was a new headlight switch (Crown # J5751098) and a new dimmer switch (Crown # J5461816). I also needed the dimmer switch electrical socket connector (AC Delco # 89581YB). Next comes the fun part. Locate the two power wires for the headlights where they come out of the junction block on the driver side firewall (one wire for low beams and one for high beams). See the pic below for the connections. Cut these two wires. Now connect up two relays, one for high beam and one for low. Connect the wires you just cut from the junction block to pin 86 (one on each of the relays). Connect the other end of the wires you cut (going out to the headlights) to pin 87 on the relays (be sure to connect low and high to the right relays). Now connect a direct wire back to your battery (through a fuse) to pin 30 on each relay. Then simply ground pin 85 on each relay. Each relay should now have 4 wires on it: fused power from the battery on pin 30, output power to the headlights from pin 87, activation power from the junction block on pin 86, and ground on pin 85. Now when you switch on the headlights and use the dimmer, you are actually applying 12V to the activation coil on the relays (one at a time depending on low or high beam selected on the dimmer switch). These relay activation coils only draw about 1 amp of current through your headlight and dimmer switch wiring. Nowhere near the 10 amps or so two halogen headlamp bulbs would draw. The power for the headlights is actually coming straight from your battery (through a fuse you hopefully installed) and the relays (normally capable of 30 amps each).
Even if you're not experiencing burned wiring or electrical connectors, many report brighter lights when doing this mod as well. So may be a great choice and it's easy and cheap to do. And who doesn't like modding something else on their Jeep just for the fun of it?
First off was a new headlight switch (Crown # J5751098) and a new dimmer switch (Crown # J5461816). I also needed the dimmer switch electrical socket connector (AC Delco # 89581YB). Next comes the fun part. Locate the two power wires for the headlights where they come out of the junction block on the driver side firewall (one wire for low beams and one for high beams). See the pic below for the connections. Cut these two wires. Now connect up two relays, one for high beam and one for low. Connect the wires you just cut from the junction block to pin 86 (one on each of the relays). Connect the other end of the wires you cut (going out to the headlights) to pin 87 on the relays (be sure to connect low and high to the right relays). Now connect a direct wire back to your battery (through a fuse) to pin 30 on each relay. Then simply ground pin 85 on each relay. Each relay should now have 4 wires on it: fused power from the battery on pin 30, output power to the headlights from pin 87, activation power from the junction block on pin 86, and ground on pin 85. Now when you switch on the headlights and use the dimmer, you are actually applying 12V to the activation coil on the relays (one at a time depending on low or high beam selected on the dimmer switch). These relay activation coils only draw about 1 amp of current through your headlight and dimmer switch wiring. Nowhere near the 10 amps or so two halogen headlamp bulbs would draw. The power for the headlights is actually coming straight from your battery (through a fuse you hopefully installed) and the relays (normally capable of 30 amps each).
Even if you're not experiencing burned wiring or electrical connectors, many report brighter lights when doing this mod as well. So may be a great choice and it's easy and cheap to do. And who doesn't like modding something else on their Jeep just for the fun of it?

