I was getting warnings from that display for the same things, rear light failure and low coolant warning. I filled the coolant reservoir and I found the high center brake light had a bulb out. Simple fixes thank goodness.

 

Thanks OverlandZJ for the link! I'll give it a try before spending $80 for a new switch.

 

I just noticed something today. He put a nice new big battery in. 825cca.

However...I see the alternator was replaced with a brand.....

Tough 1ne....13208.

When I Google it. It comes back to advance auto parts. 90 amp alternator? I think I'm supposed to have a 130 amp or up. Don't know if this one will cause problems or not.

When idling...it's at 14 volts. So its working...

 

A 90 amp alt should be fine. I'd want a 130 A if I were doing a lot of towing.

 

Ok, so not to thread jack, but I posted with a near identical issue before and never got anywhere. My jeep (94 ZJ) will do exactly the same thing, however it does not matter if my lights are on, I still get the clicking in the dash. Could this also be the ambient light sensor?

 

I will leave the 90 AMP on there then for now. It's new. I won't be doing any Towing thank you very much

 

It's not thread jacking, we have a similar issue.

I thought that light sensor was for the automatic mode? But I'm probably wrong though still learning the system. If I put my headlights in the on position instead of Auto I don't seem to be having that problem so far.

 

I think it is, but if it is failing I could see it sending a bad signal to the computer and messing things up. Ill try to pull mine shortly and see if that will fix it, though I have my doubts. Well see though.

 

It still could be sending a bad signal possibly. Mine may be my switch. Since it works in the On position. Wel...so far.
If mine acts up again then I may replace that sensor. If that isn't it. I will be lost...ugh

 

The 90 amp is for a jeep without rear widow defogger. That sucker draws a lot of amps!

 

Wait...are you being serious?? I didn't know if you were joking or not.

 

Well I removed my switch and it still does it. So thats not my issue. Dave that good to know.

 

Yes, My 2000 WJ is a plain-Jane cheap model Laredo with the 4.0, but as required by NY, had to be equipped with a rear window defogger. It has a 136 amp alternator from the factory. A dealer parts manager told me the 90 amp is for vehicles that don't have one. It also came with a 625 amp battery.

I've been searching my FSM and finally found the fuse. It appears it's only a 10 amp, so IDK why they tell me it draws lots of amps. You would think, being a resistance unit, it would draw more than that. Maybe that's only for the relay. I may have not looked far enough.

 

Ah yes, I forgot about the rear defog and side view mirror heaters drawing juice. That would justify the higher amp alt.
I had time today to pull the light switch, and perform the re-solder of the board and pot. I noticed after pulling the white plastic cover, the row of solder points between the circuit board and the light switch pot had hair line cracks. Thanks again OverlandZJ for that link! It just saved me $80.
Take note about cleaning the circuit board after re-soldering the contacts. I forgot this step and put everything back together, except the dash bezel. While I was driving, I saw arching from the back of the switch. Pulled it, cleaned it, no more problems.

 

That's crazy that there's only a 10 amp fuse. But it does make sense that it draws a lot.

I did read that the cooling sensor/rear light warning and a annoying singing was the display unit down there. I may eventually remove it and check for cracked solder joints. I bookmarked it somewhere so I can look back on it. Hopefully that's all mine needs.

I just bookmarked OverlandZJ's link he put up. I better check my headlight switch for that issue. Is,it expensive to buy a new headlight switch. I am terrible with electrical.

I just found this...

http://www.partsgeek.com/61w5zyg-jee...adlight+Switch

.