Headlights and parking lights don't work
- Thread starter Shel
- Start date
- City
- Redmond
- State
- OR
What year is it? Headlamp fuses should be hot all the time. You could test-light both sides of each fuse to see if one is hot one side and not on the other. If not a fuse, then possibly the headlamp switch.
FLCJ8
Legacy Registered User
- City
- Palm Bay
- State
- FL
As Randy stated, a test light is your friend.
There should be a 20a fuse labeled "Park /Tail" for the park/tail lights.
There is a fusible link in the feed going to the light switch, there is also a circuit breaker in the switch for the headlights.
Also a defective floor mounted dimmer switch/wiring can cause the headlights not to work.
As you can see on the schematic the headlight switch is common to both systems, however you could easily have two separate problems, so don't jump to changing the switch without testing.
A series of simple tests from source to load will help pinpoint the problem(s).
If all the power checks test out, (using a known good ground), it's time to check grounds at the lights.
Thanks for you reply.
I cannot locate a fuse. I checked all the fuses I could locate independent of circuit. All good.
Where is the fusible link?
I replaced broken dimmer switch and termination. ($18)
I replaced the light switch ($17). The knob doesn't stay in well. I cut open the old switch to see how it holds in place. One has to pull the extended switch opposite. the release button. Rather poor design. Still pulls completely out sometimes.
- City
- Redmond
- State
- OR
Once the knob assembly is all the way in, push down partially on the release while wiggling the switch in and out a few times. I’ve had the retainer get cocked a few times and the maneuver I described solved the problem.
What year is your Jeep? I’ll try and find a specific wiring diagram and maybe give you some wires to check.
Thanks for info on the headlight knob. I'll try that.
My Jeep is a 1984 CJ-7 Renegade. I was sent a diagram which was helpful; however, I don't know where the fuses are located. I need help on physical location of fuses and links. The fuses I found, checked them all. I checked that I have " ground to the headlight assembly. I am scheduled for a Hawaii safety check and will not pass without running lights. I am almost at the point of running wire to the lights with my own fuse and toggle switch. Your further help is appreciated.
My Jeep is a 1984 CJ-7 Renegade. I was sent a diagram which was helpful; however, I don't know where the fuses are located. I need help on physical location of fuses and links. The fuses I found, checked them all. I checked that I have " ground to the headlight assembly. I am scheduled for a Hawaii safety check and will not pass without running lights. I am almost at the point of running wire to the lights with my own fuse and toggle switch. Your further help is appreciated.
- City
- Redmond
- State
- OR
Ok. Using a test light see if you are getting power to the fat red wire that is rearmost on the headlamp switch. If there’s no power, you have to work your way backwards. Check both sides of the fuse marked “Park Tail 20”
Do you have power there? If you do, then your problem is probably in the splice under the dash. But I’m betting you don’t.
The fat red wire on the back of the headlamp switch feeds the switch, the fuse panel fuse I indicated, the horn relay, and the ignition switch. It passes through the firewall at the bulkhead connector. But first check the fusible link. It’s coming directly off the starter solenoid on the fender well. Same bolt as the battery cable. The Fusible link is a 14 gauge red wire spliced into a 10gauge red wire. The 14g red wire may look good, but see if it feels soft or really flexible, or burned! If that passes inspection, next step is to check the bulkhead connector. You can see the red 10g wire there. Check for voltage. You may need to unbolt the connector. It comes off the firewall in 2 pieces. One is power feeds. Find the red 10g wire and look at the terminals, both in the harness you just unbolted and in the bulkhead. Do they look good, not burned?
12D RED 14 is the fusible link. The triangle in the circle indicates the bolt to the solenoid. You can see where it splices to 12C RED 10. That in turn has a splices wire going to a relay, but you’re concerned with the wire going to the bulkhead connector as 12G RED 10 
Here you can see 12G RED 10 in its position at the bulkhead connector 
And here is the mating connector on the inside of the firewall. The wire becomes 12A RED 10 and goes to a splice which feeds the ignition switch, fuse panel, horn relay, and headlamp switch 
12D RED 10 is what the wire going to the headlamp switch is called after the splice. The splice looks like 4 wires coming together wrapped in duct tape.
Here’s 12D RED 10 going to the headlamp switch. Battery feed. This is the complete headlamp power feed circuit .
Do you have power there? If you do, then your problem is probably in the splice under the dash. But I’m betting you don’t.The fat red wire on the back of the headlamp switch feeds the switch, the fuse panel fuse I indicated, the horn relay, and the ignition switch. It passes through the firewall at the bulkhead connector. But first check the fusible link. It’s coming directly off the starter solenoid on the fender well. Same bolt as the battery cable. The Fusible link is a 14 gauge red wire spliced into a 10gauge red wire. The 14g red wire may look good, but see if it feels soft or really flexible, or burned! If that passes inspection, next step is to check the bulkhead connector. You can see the red 10g wire there. Check for voltage. You may need to unbolt the connector. It comes off the firewall in 2 pieces. One is power feeds. Find the red 10g wire and look at the terminals, both in the harness you just unbolted and in the bulkhead. Do they look good, not burned?
12D RED 14 is the fusible link. The triangle in the circle indicates the bolt to the solenoid. You can see where it splices to 12C RED 10. That in turn has a splices wire going to a relay, but you’re concerned with the wire going to the bulkhead connector as 12G RED 10 Here you can see 12G RED 10 in its position at the bulkhead connector And here is the mating connector on the inside of the firewall. The wire becomes 12A RED 10 and goes to a splice which feeds the ignition switch, fuse panel, horn relay, and headlamp switch 12D RED 10 is what the wire going to the headlamp switch is called after the splice. The splice looks like 4 wires coming together wrapped in duct tape.Here’s 12D RED 10 going to the headlamp switch. Battery feed. This is the complete headlamp power feed circuit .
- City
- Ducor
- State
- Ca
I had the same problem with a Toyota Land Cruiser “FJ 40”. I bought it from a friend of mine about 15 years ago. When I got it home, I discovered that none of the lights worked. It ended up being a bad dimmer switch in the floor. The early land cruisers have the same type of dimmer switch that our Scramblers have. Once I changed the dimmer switch, all the lights worked with no further problems.
Worth a shot.
Worth a shot.
Last edited:
mtruckstuff
Back Home in Colorado
- City
- Loveland
- State
- CO
use this from Ebay
G4 AUTOMOTIVE HID Relay Harness 50W Resistor Headlight Power Upgrade Adapter Kit
This uses a relay to run low amperage to your headlight switch and high amperage to your headlights. Kept cooking headlight switches until I realized the headlight switch was receiving full amperage. Because each headlamp is wired directly to the battery, you also get brighter headlights. Win, Win!'83_401V8_CJ8
New member
- City
- Cut & Shoot
- State
- TX
CJ's are notorious for bad electrical ground issues as they are body grounded & also prone to corrosion
Check the switch. My Scrambler came from the gulf and had serious corrosion issues. Once I determined the switch was the problem, I ordered a new one through one of the vendors. The new switch was worse than the original so an eBay listing got me a low mile oem switch and the old girl has never been so happy. Electrical on these things is taxing, at best. Good luck.