fuse blows when headlights turned on

masteroak · 06-27-2009, 05:07 PM

15 amp fuse keeps blowing when I turn my headlights on. The headlights continue to work, but the tail, turn, and brake lights do not work when the fuse is blown. Everything works fine until i turn the headlights on. Any ideas on where to start? Seems to be a short somewhere, but i have no idea where to start the process.
Thanks for any help!

farmfuel · 06-27-2009, 05:16 PM

Do you have a trailer wiring harness? 4 pin flat or 7 pin round (RV-style)?

I'd check that first to make sure that you don't have a short to ground. If you DO have a 7 pin trailer harness, unplug it from the driver's side kick panel. You have to remove the driver's side taillight/lens housing to gain access. a 7 pin has multiple relays on a seperate harness. Remove this harness from the circuit just as an experiment to see if you keep blowing fuses. If you don't use the 7 pin trailer connector, you could just eleminate it from the circuit all together by simply pluging the the main harness into the taillight harness. It'll all make sense once you tear into it.

Firestorm500 · 06-27-2009, 06:20 PM

Headlights are on a separate circuit with a breaker.

You may have a taillight or clearance light bulb that has a short to ground.

You might end up taking every one of them out and reinstalling them one at a time until the fuse blows.

Get a fistful of fuses before you start all this.

toast · 06-27-2009, 06:45 PM

Quote:

Originally Posted by masteroak

15 amp fuse keeps blowing when I turn my headlights on. The headlights continue to work, but the tail, turn, and brake lights do not work when the fuse is blown. Everything works fine until i turn the headlights on. Any ideas on where to start? Seems to be a short somewhere, but i have no idea where to start the process.
Thanks for any help!

Ha! I am tracing down the same EXACT problem! So far every bulb is out, including the headlight switch, but there is still continuity from both terminals on every running light socket. Getting frustrated thats for sure. I was unable to even segregate the front from the back..let me know if you figure it out! Checking the trailer wiring next.

masteroak · 06-27-2009, 08:52 PM

[quote=farmfuel;216881]Do you have a trailer wiring harness? 4 pin flat or 7 pin round (RV-style)?

I do have the 7 pin harness. It all started when I went mudding in the field behind my house during a big rainstorm. Prior to that, everything was fine. Also, I took off the rear hatch panel and was going to replace the speakers, but ended up not completing this. Are any of the wires in the rear hatch likely to be the culprit?
Thanks! I will start messing tomorrow morning and see where I get.

winston427 · 06-27-2009, 08:52 PM

Have either of you been inside the rear hatch panel lately? Possibly found a loose connector and plugged it together?

Check this thread and it may have an answer.
http://www.cherokeeforum.com/f2/dreaded-electrical-sizzle-17743/

masteroak · 06-27-2009, 08:53 PM

Ha! I am tracing down the same EXACT problem! So far every bulb is out, including the headlight switch, but there is still continuity from both terminals on every running light socket. Getting frustrated thats for sure. I was unable to even segregate the front from the back..let me know if you figure it out! Checking the trailer wiring next.[/quote]

Sorry you are going through the same thing. Let me know if you figure anything out and I will do the same.
Mike

masteroak · 06-27-2009, 09:03 PM

Quote:

Originally Posted by winston427

Have either of you been inside the rear hatch panel lately? Possibly found a loose connector and plugged it together?

Check this thread and it may have an answer.
http://www.cherokeeforum.com/f2/dreaded-electrical-sizzle-17743/

You are a genious! I owe you a cold one or 12...
Went out and disconnected the plug which I was messing with when I was going to replace my speakers and thought it was a connect between the left and right speakers. The other post does not give any clue at to what the connection is for. Anyone have any idea?

winston427 · 06-27-2009, 09:09 PM

The only thing I could find was that it is for the license plate light on an XJ with the factory swing out tire carrier because the tire covers the stock plate location. I looked at my 87 junker and that plug is connected for the plate light and the plug for the standard plate light is not. Somehow when both are connected it creates a ground fault circuit that blows the fuse.

Firestorm500 · 06-28-2009, 01:24 AM

Quote:

Originally Posted by winston427

The only thing I could find was that it is for the license plate light on an XJ with the factory swing out tire carrier because the tire covers the stock plate location. I looked at my 87 junker and that plug is connected for the plate light and the plug for the standard plate light is not. Somehow when both are connected it creates a ground fault circuit that blows the fuse.

Yeah, and in Europe they use those wires to power 2 license plate lights instead of our 1.

Their plates are longer.

06-27-2009, 05:07 PM	#1
masteroak Newbie Join Date: Jun 2009 Posts: 26 My Photos 1991 Cherokee Year: 1991 Model: Cherokee Engine: 4.0 H.O. Misc Accessories: Stock...today	fuse blows when headlights turned on 15 amp fuse keeps blowing when I turn my headlights on. The headlights continue to work, but the tail, turn, and brake lights do not work when the fuse is blown. Everything works fine until i turn the headlights on. Any ideas on where to start? Seems to be a short somewhere, but i have no idea where to start the process. Thanks for any help!

06-27-2009, 05:16 PM	#2
farmfuel Member Join Date: Nov 2008 Location: Dallas Posts: 154 My Photos	Do you have a trailer wiring harness? 4 pin flat or 7 pin round (RV-style)? I'd check that first to make sure that you don't have a short to ground. If you DO have a 7 pin trailer harness, unplug it from the driver's side kick panel. You have to remove the driver's side taillight/lens housing to gain access. a 7 pin has multiple relays on a seperate harness. Remove this harness from the circuit just as an experiment to see if you keep blowing fuses. If you don't use the 7 pin trailer connector, you could just eleminate it from the circuit all together by simply pluging the the main harness into the taillight harness. It'll all make sense once you tear into it. __________________ 1993 Cherokee, 2WD, 2 door, L6, AX-15, D44 1989 F350 SRW 4X4, D60 front, Sterling 10.25 rear, Banks turbo'd 7.3IDI, ZF-5, BW1356 1978 Bronco 400M, NP435, NP205, 44 front, 9" rear, 35X15.50 Swamper TSL's, 9" Skyjacker lift, chopped top, no doors; summertime buggy 2008 Tiger 20' car hauler trailer

06-27-2009, 08:52 PM	#6
winston427 Junkyard pillager Join Date: Feb 2009 Location: Lebanon, TN Posts: 5,368 My Photos 1991 Laredo Cherokee Year: 1991 Laredo Model: Cherokee Engine: 4.0 Transmission: AW4 Transfer Case: NP231 Front Axle: Dana 30 3.55 soon to be 4.56 Rear Axle: 8.25 3.55, got a D44 waiting for a regear to be installed Tires: 33x12.5x15 Dunlop Mud Rovers on 15x10 black steelies Lift Specifications: 6.5 inch Misc Accessories: hours of profanity, Le Baron hood vents, ZJ tie rod, ZJ pitman arm, CSF 3 row radiator	Have either of you been inside the rear hatch panel lately? Possibly found a loose connector and plugged it together? Check this thread and it may have an answer. http://www.cherokeeforum.com/f2/dreaded-electrical-sizzle-17743/ __________________ Why is it called common sense if it's not very common? 89 XJ 4.0, AW4, D30, D35 91 XJ 4.0, AW4, D30, 8.25 01 XJ 4.0, AW4, D30, 8.25 89 Wee J

06-27-2009, 09:09 PM	#9
winston427 Junkyard pillager Join Date: Feb 2009 Location: Lebanon, TN Posts: 5,368 My Photos 1991 Laredo Cherokee Year: 1991 Laredo Model: Cherokee Engine: 4.0 Transmission: AW4 Transfer Case: NP231 Front Axle: Dana 30 3.55 soon to be 4.56 Rear Axle: 8.25 3.55, got a D44 waiting for a regear to be installed Tires: 33x12.5x15 Dunlop Mud Rovers on 15x10 black steelies Lift Specifications: 6.5 inch Misc Accessories: hours of profanity, Le Baron hood vents, ZJ tie rod, ZJ pitman arm, CSF 3 row radiator	The only thing I could find was that it is for the license plate light on an XJ with the factory swing out tire carrier because the tire covers the stock plate location. I looked at my 87 junker and that plug is connected for the plate light and the plug for the standard plate light is not. Somehow when both are connected it creates a ground fault circuit that blows the fuse. __________________ Why is it called common sense if it's not very common? 89 XJ 4.0, AW4, D30, D35 91 XJ 4.0, AW4, D30, 8.25 01 XJ 4.0, AW4, D30, 8.25 89 Wee J

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06-27-2009, 06:20 PM	#3
Firestorm500 Senior Member Join Date: Apr 2009 Posts: 610 My Photos 1987, 1992 Cherokee Year: 1987, 1992 Model: Cherokee Engine: 4.0, 4.0 HO Transmission: 4 spd auto OD Transfer Case: New Process Tires: LT 235/75R15 Hankook Lift Specifications: stock Misc Accessories: Warn XD9000i (87)	Headlights are on a separate circuit with a breaker. You may have a taillight or clearance light bulb that has a short to ground. You might end up taking every one of them out and reinstalling them one at a time until the fuse blows. Get a fistful of fuses before you start all this.

06-27-2009, 08:53 PM	#7
masteroak Newbie Join Date: Jun 2009 Posts: 26 My Photos 1991 Cherokee Year: 1991 Model: Cherokee Engine: 4.0 H.O. Misc Accessories: Stock...today	Ha! I am tracing down the same EXACT problem! So far every bulb is out, including the headlight switch, but there is still continuity from both terminals on every running light socket. Getting frustrated thats for sure. I was unable to even segregate the front from the back..let me know if you figure it out! Checking the trailer wiring next.[/quote] Sorry you are going through the same thing. Let me know if you figure anything out and I will do the same. Mike

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