Khawk2

Hello all, I have a 1997 GCL 4.0L which I'm considering installing a headlight relay kit to improve the headlights. Two questions I have for anyone who has already done this, first how do you compensate for the light out message on the VIC from the one headlight plug that is not used or do you just ignore it? Second is it better to assemble your own relays and harness or purchase a kit. If buying kit, which one? Any information is appreciated.

Charlie Foxtrot

The relays are just Bosch relays (or clones - Lucas, Potter Brumfield, etc) and you can make the harness up out of 12 ga wire MTW (stranded; MTW = Machine Tool Wire; it is oil resistant, flexible & very durable and more than able to carry 30 amps in free air) and good quality crimp on connectors. I'm not sure how to fake out the VIC but you will be using the headlight plugs. Do you need a diagram, pics?

cliffy

For the ease, I used a kit on my XJ. I think I could make a nicer one but there just isn't time these days.

Khawk2

Thanks for the feedback, I think I'm okay as far as the wiring part, thanks for the relay suggestions. My main concern is how to manage the VIC warning messages. I will probably assemble my own kit and work on the VIC as a continuing project.

jordan96xj

I'm not an expert, but if the headlight plug is a typical one, I'm thinking the only thing the VIC can be watching for is that the circuit(s) is closed. Which with the plug disconnected it is not. So you will need to close it, but of course, you can not just jump from the positive to the negative or you will short circuit it and blow a fuse up stream, or worse (melt wires). So you will need to find out what resistance the headlamps provide, and create a connector that provides that amount of resistance, and then close that circuit with a resistor inline to match what a headlamp would provide. I can't imagine that the VIC would know the difference as long as the circuit is closed.

Nick-B

I made my own harness for my '97 GC. I plugged into the existing line on the pass side for the switching and the drivers side is not used and I haven't gotten any "light out" alert on the VIC. You should be good to go Bro!

Khawk2

Jordan96 and Nick-B,

Thanks for the information I will check out the VIC with one lamp unplugged to see if it shows an error. I purchased a set of resistors that are marketed for turn signals and taillights thinking they might be correct to fake out the VIC for headlights. I didn't know if the relay coil would satisfy the VIC for the side used or if it would need a resistor also. I also wondered which side of the bulb if monitored would be used high, low or both. If my case is like Nick-B then it will be simple. When my schedule slows down again I will do further testing to determine how to proceed.

Thanks Guys,
Keith

mrbill

Why dont you use the left and right headlights as independent power sources for your added circuits? It would require two relays of course, but may be a little easier to wire and provide a more balanced load for the existing circuits.

Khawk2

mrbill, Good thought however, I believe that if the headlights are not monitored by the VIC then both high and low circuits end up at the same point on the headlight switch. I will need to unplug one headlight and see if the VIC detects the bulb out on the side being tested. I have the FSM but have not had time to see if there is a wiring diagram for the headlights.

Thanks

Hapdad

If you are only planning on running stock lamps ( or LED's) you should be just fine with a bought harness. If you plan on running higher wattage than stock lamps (which is likely illegal on the road by the way) then you will want to look at building your own. I run hella H4's that are 55/100 watt. the low beam is legal ( i think anyway) but the high beam is not and as a rule I do not show them to other traffic (a**holes not included). I used bosch 30 amp automotive relays, 12/3 SJOOW wire (oil and water reisistant and available at lowes), permaseal connectors for waterproof connections, and ceramic headlamp connectors (to handle the heat), and ARB glass housings. The parts works together as a system flawlessly. bright tight pattern on low and high beam. The low beams are brighter than the high beams from the stock lamps.. Of course I drive an XJ.. housing are different but that is the main difference..
Hapdad

Khawk2

Hapdad
Thanks for the information, my project has stalled due to lack of time. So far I have only procured the headlight connectors. Thanks for the wire tip I will check that out next time I am at Lowe's. Most likely I will restart the project mid to late summer.

Thanks to all for the inforamtion.