Dim headlights

[Stonewall83]

I have an 83 J20 that I’m working on that is all stock. I’ve put a new battery and new headlights in. All stock replacements, however, the headlights are very dim. I don’t see anything in the fuse block marked “Headlights”. Is there a relay or anything that could be faulty and if so where would it be located?

[tgreese]

Welcome from Boston.

There is a circuit diagram for 1983 here: https://oljeep.com/gw/elec/GW_wiring.html Suggest you trace through the wires on the diagram. IIRC there is no fuse for the headlights, though there may be a thermal switch inside the headlight switch (good authority says there is, but I have not been able to confirm this anywhere). Power for the lights comes from the battery through a fusible link up to the dash and ammeter. It then continues to a splice where it branches to the light switch. From the light switch, it goes to the foot-operated dimmer switch and out from the dash and across the front inner fender.

I would disconnect the bulkhead connector for the wiring harness that goes to the front of the Jeep, and jumper the gray wires individually to the battery. If the lights are bright, this indicates a problem with the dimmer switch, headlight switch, or connecting wiring. If not, the problem is in the front of the truck. Continue similarly until you isolate the problem.

[candymancan]

Do the headligjts get brighter when you rev the engine ? Meaning are they dim in drive when at stop lights. But brighter when you drive off or in park at high idle.

An issue i noticed on these Jeeps is too low if an idle like 500-550 even 600 is too low for an alternatir to supply proper voltage when you use lights and blower motors etc. I upped my idle to 700rpm and that fixed my issue completetly

[Stonewall83]

I have not noticed the lights getting brighter with higher rev. Although I do believe my idle is a bit low and planned on adjusting that up. If that doesn’t work I will try the jumper method to see if I have a bad switch.

[candymancan]

Install a tachometer. Its veey easy. Theyre like 15$ or 10$ in autozone. Just wire the thing up to the ignition coil. And to a keyedpower switch.. meaning a power switch that gives 12v when the key is turned on only.. usually they are orange wires i noticed. Like the cig lighter wire is what i put mine on. Easy peazy. Love having a tach.. i shoved mine between the dash and windshiled drivers side.. stays put there

[Stonewall83]

I have an aftermarket gauge cluster. Will definitely get a tach as well. Appreciate the help and will fill you in on the results.

[letank]

the headlight switch with theoretical built-in thermal fuse ages poorly, I used to replace it every 100Kmiles... Otherwise the best way is to use one of these relay powered headlight harness, of make your own.

Rick's original design , which included a thermal switch and nice ceramic headlamp connectors. His design was good , I bought one.
http://www.ifsja.org/forums/vb/showthread.php?t=184659

after Rick's passing, other choices are available

https://www.fsjnetwork.com/forum/viewtopic.php?t=17821

from one of our skilled mate:
https://www.fsjnetwork.com/forum/viewtopic.php?t=18630

or quick and dirty: snip the wires on the inner fender and add A relay for each Hi and Lo and feed from the battery, and convert to H4 headlights

[tgreese]

My J20 with H4 headlights -



My article about CJ lights, applicable to these Jeeps - http://www.earlycj5.com/xf_cj5/index.ph ... il.142321/

The advantage of Rick's harness is it takes over the existing headlight plugs and thus you don't need to cut any wires. With a bad headlight switch it might still work. The headlight plugs should have enough power to drive the new relays.