Headlight Wiring

[scoobyxj]

Get a VOM and test the voltage at the headlight plug with the engine idling. If it is above 12.5 volts then a harness upgrade will not make any noticeable difference for you. On my '01 the voltage at the headlight was 12.9 volts so spending time and money on a harness would be pointless.

This doesn't mean that ALL 2001's will be the same. I've heard of some that measured less that 12.0 volts at the headlight plug. But a tester is only, like, $10 so it is dumb not to get one and test your own connections before spending the time and money on a harness upgrade.

Remember you need to have the headlight connected when you do this. You won't get an accurate voltage reading without the current draw of the light.
Also the working voltage of a operating vehicles charging system is closer to 14v (my 2000 holds 13.8v when running without any acc. on)than 12v.

 

[Randy_66]

This is going to sound absolutly crazy, but do any of you think this stuff will work?
http://www.wsdeans.com/products/wire/index.html
I've used their products on a number of occasions on my RC's and have always had good luck with it, plus working at a hobbyshop, I can get an employee discount on it too!

It sounds good in theory, dc current travels along the surface of the strands, more strands=more surface=more juice arriving at the work end. Whether or not it is enough more effective to justify what they want for it is a whole other question.

 

[elementip]

I've got Daytime Running Lights (Factory) in my 98 XJ -

I'd like to upgrade the harness like everyone else, but how do I do this while keeping the DRL?

Is there a special DRL Relay? From what I've been able to gather from the internet, the high beams are put in series while DRL is active, and then parallel when the high beams are on.

I'm pretty sure I'll need to run the two sets of wire for the high beam circuit, but I have not worked out the details of doing so yet.

Any ideas?

 

[Littlewhitexj]

Just make it so it plugs into the stock harness, although, now that I think about it, this would make your DRL's run at full power all the time.... sorry bud, im not very good w/ electricity. Hopefully someone else can help ya out.

 

[Jeff 98XJ WI]

Does anyone know if the headlight wiring upgrade is of any real difference on an 01 XJ? (i.e. is the wiring already good enough, this just problem for the older models?) Thnx

I recently lost high beams on my '98 using stock wiring. I traced it to a burnt up pin in a multi conductor connector under the dash. I pulled the high beam wires out of that connector and spliced in a separate plug just for that wire. However, that shows you how much current the stock harness is carrying. I'm planning to add a relay harness after that incident. Jeff

 

[theksmith]

I've got Daytime Running Lights (Factory) in my 98 XJ -

I'd like to upgrade the harness like everyone else, but how do I do this while keeping the DRL?

Is there a special DRL Relay? From what I've been able to gather from the internet, the high beams are put in series while DRL is active, and then parallel when the high beams are on.

I'm pretty sure I'll need to run the two sets of wire for the high beam circuit, but I have not worked out the details of doing so yet.

Any ideas?

Ok, I may be talkin out of my ass here but...

I don't think you would need anything special. The new harness plugs directly into the plugs that where going to your lights before. It uses those inputs to trip relays to allow power to then go directly from the battery. It doesn't matter whether your old lights would have been on because of DRL sensor or becuase of the switch... they would work the same with the harness... does that make sense?

 

[5-90]

Yer talkin' out yer arse!

(Sorry, I just had to do that...)

With the lamp filaments connected in series, they're both sharing source voltage, which will make them dimmer (they both get half of what's left after connector/conductor losses. This is why DRL's aren't full high beams.) When they're in parallel, the both get full voltage, and therefore require full current.

Current is a function of voltage and resistance - reduce voltage, reduce current. Reduce resistance, increase current - you may want to Google "Ohm's Law" and "Watt's Law" to understand more.

I hadn't thought of DRL when designing my harness - I guess I'll have to. I'd planned on picking up the signal from the right light (right behind the battery) to trip the relays, which would make for DRL being full high beam. I don't know of a practical way to correct that, because I don't know the system yet (I'll have to look.) Maybe I'll come up with something, but I'll have to dig out my 99 FSM (they had DRL in 99, right?) to be sure.

5-90

 

[theksmith]

Alright, Alright! Something told me I didn't know what I was talkin bout


I didn't realize the DRL put both filaments in series. Why are they so overly complicated, why not just turn on the low beams?