Blowing fuse 8 - only RH lights on red-orange circuit

[DrJeff]

I'm reassembling my cabin and every time I turn the headlights on to the first setting I blow fuse 8. I've removed every bulb on the circuit, disconnected everything and its still happening. So I think that means I've got a short circuit somewhere... Perhaps a nicked wire or bad connection.

What's the best way to isolate the problem? I urgently need to track this down.

Thanks

[Cory W]

Know anybody you can borrow a headlight switch from for a quick test? I'd start there after what you've already checked.

[WelmoedJ]

Turning the switch on:
In what position it knocks the fuse: parking lights or main lights?

If it's the parking lights, you switch may have internal damage.
This could be due to overheating by either the main power routed through the switch or by the switch's light.

Also look at the connector if some wiring may short outside (or if burnt: inside the connector socket), or if the switch shows deforming.

You could also check directly on the wire connector with 12V power (make sure not to hit ground).
To see if the belonging lamps light normaly without blowing a fuse.
If the lamps do work, the issue is the switch.

[Bitsyncmaster]

Pull your cig-lighter lamp wire off and see it that fixes it.

[Ron]

You might get a clue by removing Fuse #2 or un-plunging the BLACK Bulkhead Connector.

[David T]

Open the R/H marker lights and look for corrosion or a bad bulb or anything that could cause a short. The front one is notorious for corroding badly. If that doesn't help you will have to follow the wire from the fuseblock to the short. A shortfinder will help if you can borrow one.
David Teitlebaum

[DrJeff]

Okay, it took a while but I tracked it down using a multimeter to test for a short to ground.

- Checked the front right marker light... corroded yes, but not the cause of the short
- Would have checked the cig bulb, but it is already out of the car
- Pulled out, disassembled, and reassembled the main headlight switch... not the problem - mine looks in perfect condition inside and out (thank you PO)
- Finally checked the LED bulbs in the Hazard lights switch, BINGO!

The hazard switch LED bulb tests good, so it may have been the way I had it jammed in there that was causing the short to ground. Once the bulb was removed everything worked fine.

Thanks everyone for all the suggestions...

Jeff

[jawn101]

Okay, it took a while but I tracked it down using a multimeter to test for a short to ground.

- Checked the front right marker light... corroded yes, but not the cause of the short
- Would have checked the cig bulb, but it is already out of the car
- Pulled out, disassembled, and reassembled the main headlight switch... not the problem - mine looks in perfect condition inside and out (thank you PO)
- Finally checked the LED bulbs in the Hazard lights switch, BINGO!

The hazard switch LED bulb tests good, so it may have been the way I had it jammed in there that was causing the short to ground. Once the bulb was removed everything worked fine.

Thanks everyone for all the suggestions...

Jeff

Ah, too late to help with this one. I saw your thread post and came in here just to say the same thing happened to me when I had installed the bulb in the switch badly. Glad you found it! :)

[Timeless]

Pull your cig-lighter lamp wire off and see it that fixes it.
This problem popped up yesterday for me. #8 blows as soon as parking lights turned on. No right side markers/lic lamp or instrument cluster gauge illumination. Unplugged all cig lighter wires, checked right marker sockets - clean, checked rheostat wires - ok. Fuse box and other related wiring is good. Left running lights and all 4 headlights and signals/hazard working. Headlight and hazard switches do NOT have LED bulbs, headlight switch original. Entire vehicle has LED bulbs.

[JBaker4981]

Headlight and hazard switches do NOT have LED bulbs, headlight switch original. Entire vehicle has LED bulbs.

First thing that comes to mind is that one of those LEDs on that Circuit for Fuse #8 is in the socket backwards. I know you mentioned that the Headlight switch AND Hazard Switches are not LED, but this is the exact behavior that occurs when your LED is in the Headlight Switch Socket backwards. Pops fuse 8 as soon as you engage. My thought is that since neither switch is LED, this reverse polarity issue exists in another socket and the fact that this occurs with the Hazard switch reinforces my theory.

Pull your bulbs, flip them around.

I have an LED Conversion guide for the car on our website under the Lighting Section if it's helpful
https://tn-dmc.com/downloads

[Timeless]

First thing that comes to mind is that one of those LEDs on that Circuit for Fuse #8 is in the socket backwards. I know you mentioned that the Headlight switch AND Hazard Switches are not LED, but this is the exact behavior that occurs when your LED is in the Headlight Switch Socket backwards. Pops fuse 8 as soon as you engage. My thought is that since neither switch is LED, this reverse polarity issue exists in another socket and the fact that this occurs with the Hazard switch reinforces my theory.

Pull your bulbs, flip them around.

I have an LED Conversion guide for the car on our website under the Lighting Section if it's helpful
https://tn-dmc.com/downloads
Thanks for that. Engaging the hazards does not blow the fuse - only the headlight switch engagement. Everything electrical has been perfect since day 1. The HVAC LEDs are checked and functioning as designed. FWIW the cluster lights up with a larger fuse installed as a test, but no right side markers/lic./tail lamps. I removed the larger fuse after the test.

[Bitsyncmaster]

Thanks for that. Engaging the hazards does not blow the fuse - only the headlight switch engagement. Everything electrical has been perfect since day 1. The HVAC LEDs are checked and functioning as designed. FWIW the cluster lights up with a larger fuse installed as a test, but no right side markers/lic./tail lamps. I removed the larger fuse after the test.

I had that fuse blow and it turned out to be one of the screws that hold down the shifter plate screwed into a wire in the harness. Try to back out those screws.

[Timeless]

I had that fuse blow and it turned out to be one of the screws that hold down the shifter plate screwed into a wire in the harness. Try to back out those screws.
Thanks. I have the plate removed currently to check cig lighter wiring and replace with a USB socket. I'll check the wiring in there.

[JBaker4981]

Thanks for that. Engaging the hazards does not blow the fuse - only the headlight switch engagement. Everything electrical has been perfect since day 1. The HVAC LEDs are checked and functioning as designed. FWIW the cluster lights up with a larger fuse installed as a test, but no right side markers/lic./tail lamps. I removed the larger fuse after the test.

Got it. That really seems to be the Headlight Switch - and you are running an InCan in it? Have you replaced it by chance or is it super old?

[Timeless]

Got it. That really seems to be the Headlight Switch - and you are running an InCan in it? Have you replaced it by chance or is it super old?
InCan and quite possibly original. (both bulbs bench tested) I made some progress just now. Unplugged the black connector at the bulkhead and turned on the parking/headlights - no fuse pop and cluster illumination and right front marker lamp working - rear lights out. Unplugged the right side aftermarket license plate lamp and reconnected with electrical tape over terminals and zip tie secured to the factory harness on the closing panel. Reconnect black bulkhead connection. Rechecked and all is working with no fuse pop but the headlight and hazard switch still do not illuminate.

[Timeless]

Update: drove last night with zero issues. I noticed the headlamp switch is lighting up but the hazard switch is not. I have switch LEDs from Dgo that I may install.