Headlight Fuse Issues

[Doc]

Ok, when I took possesion of the 1993 fzj80 the wifey drives the headlights were funky.

When I say funky, I mean when you turn the headlight switch one click (marker lights only) everything comes on, markers and headlights both. Turning the switch to the second position resulted in no change in lighting.

Using High beams for more than 30 seconds blew the fuse

Now that I have HIR's installed in both high and low spots, using high beams blows the fuse in 3-5 seconds.

Any idea what's going on here?

Would the Slee harness adress these issues?

 

[Scamper]

Probably others more knowledgeable than me about this since my only experience had to do with a 1980 Tercel. I had a very similar problem and found that the switch itself was worn, leading to both sets of contacts making the connection at the same time. This would be providing power to both hi and lo beams at one time which is something they're not designed for. I blew a lot of fuses before I figured it out. I ended up disassembling the switch and rebuilding it at the time (a real Rube Goldberg job ).

I don't know if that can happen with these trucks since I imagine Toyota redesigned the switch in the past 20 years. But who knows... If the switch feels really loose and wobbley, that may be the problem.

 

[Doc]

Sorry. I was unclear.

At the first switch position, the marker lights and low beam headlights come on, not both the high and low beams.

Now that I re-read that it looks like all 4 head lights are on at once, which is not the case here.

 

[IdahoDoug]

Doc,

Tough to call from here as obviously somebody's been into your wiring. Without knowing at what point the previous owner started messing with things (switch-relays-headlamps), it would be a guess if the Slee harness would help. For the money, that's what I'd try first, though. Can't even get an automotive electrical shop to look at it to diagnose for what the Slee harness costs.

DougM

 

[Safado]

You've got a short somewhere. It could be in the stock harness, and a highly recommended upgrade could just take care of it for you. It's going to be something you want anyway so you might as well just get it and take that part out of the equation...if it still blows the fuse...you'll still have the upgraded harness once you finally fix it. It could very well be the switch itself, I have a 93 EWD I've never used that you're welcome to buy for the CDAN price. Good luck and post back if it doesn't work.

 

[Beowulf]

I may be wrong but it seems like the Slee harness plugs into the factory harness. If there is a problem in the wiring it will still be there with the Slee harness.

My recommendation would be to figure out what is going on, then upgrade.

-B-

 

[Doc]

How would I even begin the diagnosis process?

The fuse only seems to blow once you pull the lever for brights. You get a few seconds of your bright lights, then POW- lights go out.

When I replace the fuse, the 15 amp headlight fuse is HOT.

 

[cary]

My vote is that it is the switch itself. You might try and trigger the high beams through the relay to see if the fuse blows to isolate the problem as wiring versus the switch.

Cary

 

[Scamper]

Doc,

An EWD would really be helpful here. Some rambling thoughts...One easy thing I'd suggest to start, is to pull the headlight bulb connectors off (all of them) and turn the circuit on. If the fuse blows, then there's a short somewhere in the wiring. If not, then at least you know it requires a completed circuit to cause the short. You could also try this by pulling one side at a time to see if you can at least narrow it down.

If it's easy to do (I don't know, never had to try) you can try pulling the cover off the steering column to get at the switch connections and see if they are shorting out in the various "on" positions (need a multimeter).

I belive there is also a relay that controls the headlights (???). If so, then you could test between the switch and the relay, and between the relay and the headlight connectors for continutity and/or grounding.

Then it's time to break out the multimeter again (or buy one if you don't have one) and start tracking backwards. The EWD is probably required unless you have a lot of time and patience... Good luck, since electrical problems can be a bear to isolate.

 

[Doc]

I've got the FSM, I think it includes the EWD, the problem is I'm a complete idiot when it comes to circuitry and electronics.

 

[lurker]

I'd disconnect the headlights and try again. If you reblow the fuse again then I'd (replace fuse, then eng. power off) ohm from the headlight connectors to ground with the switch in the questionable position. Both shouldn't ground. You'll have to start disconnect plugs as you work your way back to the drivers switch.

Good luck.

 

[Doc]

Huh? I have no idea what you just said.

Ask me to do a birf job, no problem.

Ask me to ohm something out, and I get all tingly inside. I do have a 'multi-meter' but I wouldn't know where to put which lead.

 

[lurker]

Huh? I have no idea what you just said.

Ask me to do a birf job, no problem.

Ask me to ohm something out, and I get all tingly inside. I do have a 'multi-meter' but I wouldn't know where to put which lead.

With the ohm meter the leads (red/black) don't matter.

You'll find 2 prongs in the head light connector, one should go to ground (engine/chassy/ect...) and the other should go tho the switch.

I this case we suspect that the wire to the switch is grounded somewhere. The problem is where? This is why you need to start breaking the connection towards the switch. If say the wire from the head light towards the switch is 1 foot long before you see a connector and you ohm it and you see 0.0000 it's grounded somewhere (remember one should be but not both), now you disconnect the connector with the multimeter wire still in the headlight connector and it should go to -999999.99999
(open) GREAT! now move the ohm multimeter wire from the headlight to the newly disconnected wire, do you see a short again? Then you find another connector and work your way back towards the drivers switch.

Sooner or later you'll see a gum wraper in a fuse box or some thing? You can also play with the driver switch to get a better understanding if it's flakly also.

Good luck and keep asking questions if necessary.

 

[Safado]

I may be wrong but it seems like the Slee harness plugs into the factory harness. If there is a problem in the wiring it will still be there with the Slee harness.

My recommendation would be to figure out what is going on, then upgrade.

-B-

It uses from the switch to the DS harness. That is how the trigger is set. The rest is done with the new harness. Do I think it will fix the problem...about a 1 in 10 chance it will. But it's kinda hard to walk someone through a DMM over chat.

Doc, I think the suggestions that SCAMPER gave are the easiest and best way to go. Just unplug all the lights and then turn the switch. If the fuse blows...it's a problem in the wiring itself or the switch. If not...connect back one at a time and see where you blow.

 

[Beowulf]

The FSM does not include the EWD. The stock lighting system has a headlight relay (99% sure of this but haven't checked the EWD to confirm.) The headlights are negative switched.

Doc,

This might be the time you want to get a shop involved. If you're going to try to fix this yourself first then I would tackle it something like this:

Buy a 12v tester at most any auto parts store. It is small light with an alligator clip on one end of a wire and an ice-pick looking tool on the other end. The ice-pick looking tool has a 12v bulb and will illuminate when it gets 12v flowing through the wire. In general, you attach the alligator clip to a ground (-12v) and probe a wire where you expect to have +12v. Or vice-versa; clip to +12v and probe where you expect a wire to be grounded. To test, place the alligator clip on the (+) terminal of your battery and touch the probe to the (-) terminal. The lamp will illuminate but you don't know if you have a full +12v or more or less. The DMM would be used to measure the actual voltage.

The DMM can be set to "Ohms" which measures resistance in a circuit. In this case you are basically looking for "open" or "continuity" in wires since it's pretty obvious you have a short (i.e. continuity) where it is not supposed to be. You measure resistance by putting one probe (+ or -) to one end of a wire and the other probe to the other end of the same wire. You should get zero (0.000) ohms which means there is no resistance. An "open" would give you an infinite resistance (represented by all 9's on the DMM display.) You should first test this by placing the 2 DMM probes together with the DMM on and set to measure ohms (resistance) Then notice what happens when you separate the 2 DMM probes.

The DMM can also be set to measure DC voltage. This is usually represented by a straight line over a dotted line next to a V. You will use the (+) probe and touch it to the (+) terminal on your battery and the (-) probe to the (-) terminal on your battery. You should see approx +12v. You would use this to check for the proper voltage in a circuit but you would need to know what to look for by reading the EWD.

With these 2 basic tools, the EWD, and some problem determination skills, you should be able to determine where the problem lies. Since you don't have the EWD it might help to look at the headlight wiring diagram on Christo's web site. That will give you some idea of what wires should be +12v and what wires should be -12v. Maybe someone will post a scan of the headlight circuit to get you started.

-B-has

 

[Doc]

I have the 12v tester already, and an analog multi meter- not digital.

I'll do some tests tonight and report back on what I find.

would one hire an electrician in this case (if I wanted to farm out the labor) or an auto shop? I think an electrician might be cheaper and a quicker diagnosis?

 

[RavenTai]

If you mean a household electrician unless he has some automotive experience he will be quite lost, auto electrical systems are much more complicated than household

 

[Scamper]

-B- : no relay? okay...I just thought everything running on this rig went thru a relay. Exposing my biases And yes, Toyota does like the negative switching. Can be a bit unfriendly to someone unsuspecting.

Yeah, I'd agree with Raven on the issue of electricians. If you farm out the work, use an auto electrician.

Anyone from MUD nearby? (i.e., anyone who knows anything about wiring?) If you were near NJ, I'd be glad to help you out.

 

[Doc]

Ok, here's what I did tonight. It was a very interesting evening.

First I pulled off all of the light connectors, and turned the lights on, brights too, and left them on for a minute, flashed the lights a couple of times and checked the fuse. Not blown. Not even warm.

Interesting.

Then I plugged in the high and low bulbs on the passenger side. Again I turned the lights on, flashed the brights a couple of times, and the fuse held.

I went to plug in the drivers side lights and found THIS:

Notice the extra wire in there? That's the drivers side outermost bulb connector (low beam?) There's a black wire spliced into the OE wires and 'insulated' with electrical tape. Here's where that wire went:

Yeah, the drivers side blinker.

Ok. I thought I had the culprit. So I get the introduced wire cut out of there and the OE wires re-insulated. I plug the drivers side connectors back in, and turn the lights on. Nothing happens. No lights on drivers or passenger side. Somehow, that spliced in wire was supporting all the lighting on the truck.

My first reaction was to check the fuses. The fuse that kept blowing out was the 'tail' fuse on the left of the steering wheel, second from the top. It was fine. I checked both headlight fuses in the engine bay, both fine.

What's that relay that says HEAD on it? For the headlights? How do I check to see if it's working?

My next thought was that I have a blown a fuseable link. How do you check the fuesable links?

 

[Doc]

PS, I have marker lights, but not headlights. Sorry if that was not clear. I did not test blinkers, but assumed they were OK, since the marker lights worked.

there was no such wire on the passenger side, only on the drivers side.