Aux lights and cooling fan questions

1989 XJ
4.0l
Automatic
Completely stock.


I just wired up some auxillary lights. I essentially followed the diagram below, except that instead of running the switch to the fusebox, I tapped into the high beams, since I only wanted the aux lights on when the high beams are on. The lights are grounded directly to the battery, the relay is grounded to a screw on the fender, and the switch is grounded to a stud on the firewall.



The problem is that now the high beams, and aux lights can be turned on when the Jeep is off and the headlights are off. So, where have I gone wrong? Also, when I took out the relay to make sure it doesn't drain the battery, I notice that I can still use the "flash-to-pass." Is that normal? I've never tried it before with the Jeep and headlights off, so I wasn't sure if it's supposed to behave this way.

Now the fan. I'm not sure if it's something that I did while wiring the lights, or if it's a previous problem that I didn't notice since I don't normally idle for very long, but the electric fan isn't coming on and it is overheating.

I did some googling and looking through the Haynes manual but I'm not able to find where the fuse or relay is for the fan. I keep seeing mention about trying to run the A/C to see if the fan turns on. The A/C was removed by the previous owner, and the fan did run until recently.

Thanks!

You have obviously made a positive power path though your switch.

The factory uses one relay to enable the fog light circuit. Will get to my point in a second.

How they do this is put a relay in parallel with the high beam lamp.
When the high beams are activated, the relay activates. No switch, no way to go wrong.

On the other side of the relay, they use the Normally Closed set of contacts to run the power from the fog light switch to the Fog Lights. So when the relay is activated, the contacts open disabling the Fog lights.

So to do your AUX lights, you would use the Normally Open set of contacts. When the relay activates, the contacts close which enables your Aux circuit.

when you say the PO removed the a/c did they remove the compressor and everything? If its still there, try unplugging the compressor, then turning the a/c on and seeing if the fan comes on. That used to be my poor man's fan control on my 94.

if he pulled the compressor, what I would do is unhook the the fan, then run wires to it, and touch it to the positive and negative on the battery to see if the fan spins, to make sure the motor isn't burned out.

Sounds like you've tapped into a constant hot. If you want the aux lights to only turn on when high beams are on AND the aux switch is on then you need to tap into the signal circuit between the high beam switch and it's relay. Use the high beam signal power to power the aux switch.

WB9YZU said:

You have obviously made a positive power path though your switch.

The factory uses one relay to enable the fog light circuit. Will get to my point in a second.

How they do this is put a relay in parallel with the high beam lamp.
When the high beams are activated, the relay activates. No switch, no way to go wrong.

On the other side of the relay, they use the Normally Closed set of contacts to run the power from the fog light switch to the Fog Lights. So when the relay is activated, the contacts open disabling the Fog lights.

So to do your AUX lights, you would use the Normally Open set of contacts. When the relay activates, the contacts close which enables your Aux circuit.

Click to expand...

That makes sense and gives me some ideas. Thanks, that helps a lot!

Also just realized I posted this in the modified tech discussion. I meant for it to go in the OEM. Oops.

IslanderOffRoad said:

when you say the PO removed the a/c did they remove the compressor and everything? If its still there, try unplugging the compressor, then turning the a/c on and seeing if the fan comes on. That used to be my poor man's fan control on my 94.

if he pulled the compressor, what I would do is unhook the the fan, then run wires to it, and touch it to the positive and negative on the battery to see if the fan spins, to make sure the motor isn't burned out.

Click to expand...

The compressor itself is still in there. He said it quit working so he just removed it instead of fixing it, but everything except for the lines from the compressor to the firewall seem to be there...he wasn't really clear about it, and I didn't think to ask more since I didn't care about not having A/C anyhow. The more I was thinking about it today, I'm not so sure that the electric fan has been running in the past. I just know that I have heard a fan running when the Jeep is warm. This is the first one I've owned with the dual fan setup.

I'll give the a/c a try and if necessary try wiring it to the battery tomorrow if I get a chance. Thanks!

Foothill said:

Sounds like you've tapped into a constant hot. If you want the aux lights to only turn on when high beams are on AND the aux switch is on then you need to tap into the signal circuit between the high beam switch and it's relay. Use the high beam signal power to power the aux switch.

Click to expand...

Yup, that's exactly what I've done. It occurred to me this evening that was probably what I had done wrong, but I wasn't certain, and wasn't sure how to re-wire it so this and WB9YZU's posts help a lot. Thanks!

mhaserodt said:

Also just realized I posted this in the modified tech discussion. I meant for it to go in the OEM. Oops.

Click to expand...

I think you did post it in OEM...

But because it is not a repair, but an upgrade with non-OEM stuff, I suspect the Moderator made the judgement call and put it here in Modified Tech.

No worries, it's all good

WB9YZU said:

I think you did post it in OEM...

But because it is not a repair, but an upgrade with non-OEM stuff, I suspect the Moderator made the judgement call and put it here in Modified Tech.

No worries, it's all good

Click to expand...

Ahh, that makes sense.

So I checked out the fan today, and it turns out that I either accidentally unplugged it, or unplugged it and forgot. It's running fine now. I should have suspected that I did something dumb. :dunce: