Headlight troubleshooting

[MoonForest]

Recently purchased my first which has a few issues one including a headlight problem. Stock headlights, brand new battery...

Noticed when I as about to do a quick night test drive, the headlights started flickering during idle - 1st time turning them on since owning it. I pulled the headlight knob out more, sort of holding it and they seemed to stay on while holding it. I want to say the more I dimmed the dash (by twisting the headlight knob) the less the lights flickers. Revving in neutral didn't make them brighter. I didn't drive due to the issue. Came back to it during daylight and now, nothing on the headlights.

Checked the fuse - from my understanding the 10AMP Park LPS fuse up top (https://amceaglesden.com/guide/Fuse_Panel), and all good. Been reading about a new relay setup, but would like narrow it down and get the headlights working first...although maybe there just isn't enough power getting to the headlights so would need a relay?

Removing the headlight switch. I see some ppl have luck removing a few upper dashboard bolts then tilting it out from the top? What if it doesn't tilt down, does the full dashboard need to be removed? Trying to find a guide on this but only have come across: https://amceaglesden.com/guide/Headlight_Switch_Replacement

I believe the previous owner replaced the steering column if this has anything to do with it, like grounding or knocking something loose (?). Any ground/wires to look/feel for without removing the dash? Any recommendations on troubleshooting first before swapping the headlight switch? I see other ppl have ran into this issue as well, swapping them realizing the switch wasn't the issue..but didn't mention what the actual issue was.

Thanks all

[MIPS]

The headlight B+ terminal is known to overheat and melt, adding to that there's an internal circuit breaker in the switch that can start cycling if there's too much load, however in later years it seems the factory harness is barely strong enough to handle all four lamps with OE lamps installed.

I pulled my dash and had to both replace the switch because of a burned terminal and a melted connector. Even after that I still had the lights fail with the high-beams running, so I ended up installing a plug-in relay harness kit.

[Taylor]

I would definitely go with a plug in relay harness kit. Removes a huge load off the switch. I have had mine out before. They definitely get hot and a relay kit will solve that. Make sure that the kit has a fuse for each relay.
Also check all the grounds. Those can cause many headaches.

[MoonForest]

Thanks for the advice - will plan to just replace the switch and do the relay setup. Messed with it last night and noticed they turn on when the key is in and engaged. Had to pop them on/off a time or two to turn them on. Just finicky and feels like the cable isn't fully engaging or "popping" to the fully extended out/on position. Anyways, will rip apart and investigate.

Also worth noting, checked the headlight switch ground, which according to the docs is a small ring ground on the firewall behind to the left of the brake booster/master-cylinder. (image attached)

Just bought a few relays on amazon along with some inline fuses. Seems pretty straight forward, although I haven't looked at the wires themselves to the headlights. I see the diagram here: https://amceaglesden.com/guide/%2781_-_%2788_Headlight_Diagram

I'm still a noob, so my understanding is cut into whatever wire(s) that provide power to the headlights (1 for low beams and 1 for high beams) and link with the relay(s).

One more question - since the dash will be removed, any recommendations on other things to replace in there - things that are known to break? My temp gauge is faulty, which I'd assume is the thermostat (wasn't smoking tho on a 1 hr drive) or a temp sensor - but maybe there's a known issue behind the dash?  Eagle has always been a dream car, so planning to spend some money and time on it.

Relay's if interested: https://www.amazon.com/gp/product/B074FSZWVT/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

[MIPS]

I strongly recommend you buy the prebuilt wiring and relay kit. It's only $30 and underpriced for the quality of all the connectors it comes with. It doesn't require any tape, solder or crimping unless you wish to cleanly dress the new harness. Just plug it in.
https://www.ebay.com/itm/303762913586

Thankfully you do not have to pull the entire dash to get the cluster or the switch out. If you don't have the lower tray package you can reach behind and unplug the cluster and disconnect the speedometer (careful, the end is made of plastic), then remove the screws for the fake wood bezel on the drivers side and tilt it out far enough to unplug the wiper, headlamp switch and the lighting harness for both. ISTR though there's clips or slots hiding somewhere below the cluster that are a royal pain to unclip, so you can't immediately tilt everything out.

While you are in there, run some transmission fluid down the speedometer cable and  check all the bulbs.

[MoonForest]

Nice, was looking for something like this - just ordered em. Will try to figure it out when it gets here, but guessing that male switch (not the relay or headlight female connectors) just plugs directly into the headlight switch located under the dash. Have no eyes on the headlight switch yet so that's the only unknown atm.

Noted on the dash removal and preventative checks, thank you that'll help. I do have the lower tray (83 limited wagon). Although now after looking more into the stock tray via google images I see mine has been cut out on the upper driver side section - image attached. Thought that was stock and just how AMC did business..hah

Anyway, will get after it over the next week while supplies trickle in. I'll plan to post the process in video on YT or pics here. Will add/edit with sources. TY again.

[MIPS]

It doesn't even need to make you fight under the dash. It plugs into one of the high/low beam lamp sockets under the hood and controls the relays from there. No routing through the firewall or even running cables beyond the front of the car. It converts the existing wiring into low current control wiring.

[rmick]

I have done this same mod the other thing when doing this is to separate the High and low beam power input with a separate fuse incase one blows you still have the other

[MoonForest]

The new headlight harness did the trick  didn't even mess with the headlight switch.

Now just have to figure out where to mount the relays since the length it came as isn't long enough to go past the battery - have 3M dual locking velcro which I plan to use. Worst case I'll just splice 14awg wire into all the relay wires in order to extend.

Also waiting for new headlight plastic fasteners/retainers since a few old ones broke off while removing.