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Unread 09-22-2014, 04:41 PM   #1
KayakWarrior
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76 CJ7 - Electrical failures front to back

Bought an old Jeep and attempted to drive it home. I knew from the test drive it had carb issues but overall the old beast seemed mechanically sound. 15 minutes into the ride home, the headlights went out and within seconds, the running lights slowly faded to black and then left me in the dark. I have gone through and removed all of the light assemblies as well as dropped the dash panel forward for easy access. Its now been a week of walking wires looking for metal contact and can't seem to find the electrical problem. While going through the lights, I tapped each ground penetration to 1/4-20 and threaded a 1/2" bolt through wire termination eyelet and secured it to the firewall and then put a lock-washer and hex nut on the backside with blue thread-locker. Grounds are now awesome but seem to have a dead short on the Grey/Tracer headlight wire as well as the green on the side markers and running lights up front. I covered it up when the rain started and didn't even check the rear at that point, since I believe that they all are tied together under the dash, correct?

Any ideas as to how to find my short, I have rammed my head numerous times into the roll bars trying to force the resolution into my head, but that technique does not help either.

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Unread 09-22-2014, 06:44 PM   #2
KayakWarrior
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Does anybody know how to test a headlight switch for a possible short circuit within the device. I am assuming that I should check from each terminal block to a ground point on the dash panel and see if it reads continuity through the switch body. Is there supposed to be any continuity from terminal to terminal anywhere?

Building on a zero budget or I would just spend another $25 bucks and replace the switch...However, that money would be better spent on the rebuild kit for the Carter carb that wants to self-accelerate and send the old girl down the road at 4000 rpm's without enough braking power to hold that beast at bay. Not much of a concern in wide open spaces, but here in Central Florida, its just not conducive to our local bumper-to-bumper tourist traffic.
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Unread 09-22-2014, 06:55 PM   #3
texasdave
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A test light would be helpful as would a multi-meter. The Light switch is un-fused so if it is an internal short there's no real way to tell. The running lights should be fused so you could pull that fuse and it takes away the problem then it is that circuit. You could also run a length of wire and bypass the original wire that could eliminate that wire.
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Unread 09-22-2014, 07:18 PM   #4
PanteraPilot
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I'm not sure why you think there is a short. There should be a wire associated with the headlights that is grounded. From what you described regarding the lights fading to black, you have a classic example of a bad alternator. When the alternator stops doing its thing, all power to the lights, and everything else, is pulled directly from the battery. Since the battery isn't being recharged, the battery dies out and the lights simply go dim and then dark. Is there more to this?
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Unread 09-22-2014, 10:50 PM   #5
BagusJeep
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The headlights on a CJ are not fused. The feed from the solenoid goes through a fusible link, branches off to the fuse box but feeds the headlight switch directly on the dash.

The headlight switch contains a circuit breaker, as standard anyway. If you have power going in but not coming out of the switch it is probably the circuit breaker. The breaker is a momentary breaker, in other words it goes off and comes back on momentaruly until the fault clears, a lot safer on a headlight.

The switch feeds the lamps on the panel and goes down to the dimmer switch on the floor. The floor switch chooses between low beams and high beams. It is not unusual that it fails or shorts just here, being on the fllor is not ideal.

The two grey wires then go out to the headlights.

The rear lights or tail lights come seperately from the fuse box up to the switch and is switched on a seperate circuit to the tail lamps.

The head lamps are ot connected to the tail lamps or side marker lights.

Teh atatche ddiagram does not show the side marker lights.

First thing I would check is operation of the light swtch on the dash. Does it conduct electricity.
84-86fuseboxsch-copy.jpg

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Unread 09-23-2014, 08:20 PM   #6
bigjoe
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Quote:
Originally Posted by PanteraPilot View Post
I'm not sure why you think there is a short. There should be a wire associated with the headlights that is grounded. From what you described regarding the lights fading to black, you have a classic example of a bad alternator. When the alternator stops doing its thing, all power to the lights, and everything else, is pulled directly from the battery. Since the battery isn't being recharged, the battery dies out and the lights simply go dim and then dark. Is there more to this?
I agree, sounds to me like a bad alternator or a broken lead at the alternator to recharge the battery.
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Unread 09-24-2014, 08:17 AM   #7
KayakWarrior
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Since this Jeep has seen more than its share of Cypress Swamp, I unhooked every gauge and dropped the dash panel. Headlight switch is a caked in mud and rusted heavily inside and out. Same goes for the Dimmer switch, as soon as i disconnected it, all the dash panel bulbs lit up. Woo-Hoo, finally seeing forward progress. Just gotta come up with the necessary cabbage to replace both of those parts before i can continue the electrical diagnosis. Alternator seems to be doing its job.

Guess i have time now to focus on some other pressing issues:
1 Brake system that need serious attention, completely rusted out and spewing fluid from numerous spots.
2 Working the bugs out of this CARTER carburetor, so it wont run so rich and spit so much smoke.
3 Seat-belts so my family will ride around with me. (Why do you need seat-belts when you know how to "Tuck-N-Roll"?

Thanks everyone for keeping me pointed forward with your suggestions. Asking for help hurts less than banging my head in frustration.
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Unread 09-24-2014, 10:03 AM   #8
texasdave
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One way I have worked on the dash panel is to get a couple of threaded rods or long bolts and "hang" the dash on them. I put one bolt on each end and pull it out as far as the wires will permit. It is hard for an old fat man to lay inside the Jeep trying to locate wires. Ask me how I know?
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Unread 09-25-2014, 11:53 AM   #9
KayakWarrior
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Thanks for that idea TexasDave, unfortunately i unhooked everything, which makes it all really accessible and lets me see all the lovely rust up in the corner seams. But when it comes time to rehang the dash panel it will be "supported for the reconnection process. Us old thin guys don't get under them well any easier than old fat guys, we just have a little more wiggle room once we do get contorted into oblivion
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Unread 09-25-2014, 02:19 PM   #10
ECJ-7
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Quote:
Originally Posted by KayakWarrior View Post
Thanks for that idea TexasDave, unfortunately i unhooked everything, which makes it all really accessible and lets me see all the lovely rust up in the corner seams. But when it comes time to rehang the dash panel it will be "supported for the reconnection process. Us old thin guys don't get under them well any easier than old fat guys, we just have a little more wiggle room once we do get contorted into oblivion
You Old guys are doing it wrong, pour yourself an extra large Woodfords Reserve and you'll slide right under the dash. :-) and them's the facts.
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Unread 09-25-2014, 04:17 PM   #11
Garyr2138
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You really should check out Jeephammer's threads on grounding. Did a major battery cable and grounding upgrade to my 1980 CJ7 and the results were awesome. Heavy duty battery cables, proper grounds, and terminal blocks made a huge difference. I added a power and ground block so I could add accessories later but decided to sell it before adding anything. Also added Daniel Stern headlight relays and magically my headlights, parking lights, and corner lights all started working, and i could see! Getting ready to do it all again on my 83 Cali girl CJ7 shipped straight from Cali to central FL.

Gary
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Year & Model: 1983 CJ7
Engine: 258
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Unread 09-27-2014, 04:04 PM   #12
KayakWarrior
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Fixed a door handle on an 06 Ford Fusion for a friend and he bought a new headlight switch as a trade for my labor. This is going to be a low budget project every chance I get, as I am in that "Financially Embarrassed" category these days. Popped it in the Dash Panel and instantly, I lost dash panel lights but gained running lights. Still no headlights though and I need to figure out why the fender lights wont light up now. No brake lights either but that could be the brake switch that I never bothered to check for some reason. Think my plan was to swap it out when I replace the brake booster and master cylinder.

Gonna poke around under the dash some more and see if screaming obscenities will make it work any better.
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Unread 09-27-2014, 06:56 PM   #13
KayakWarrior
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Reread some of jeep-hammers threads and decided i was intelligent enough to go back through the grounds one more time and wouldn't you know it, one bad ground connection in driver rear fender lamp had all four corners out. Passenger headlamp had the low beam connector pin sliding out and making contact with ground pin (also slide out of back of headlamp connector)...

1 deep breath followed by a quick 5 minute walk-through, not a single utterance of aggressive angry vulgarities...And the beast has lights all the way around! gonna reground that dash panel and cure that little issue of no dash lights next.

This site is an awesome consortium of Jeep knowledge and ideas. Next task is to install the Team-Rush Upgrade and need to reset the distributor. It seems that the prior owner has the distributor installed with the vacuum advance is facing fender-well, not front of motor. Plug wires are in the right firing order just rotated on the cap to make it fire close to right. Figure i can check the slop in the timing chain while that takes place. Done been all up on the Jeephammer threads on that one and looking forward to sharing some more shop time with my son.
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Unread 09-27-2014, 07:00 PM   #14
KayakWarrior
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Did a quick change of oil, plugs, filters, and tire rotation on wife's Grand Cherokee. Autozone rewards for that earned me free motor mounts for the CJ-7. Took my son and I about an hour to change both front mounts and he loved the wrench time instead of doing homework. Been a great weekend for me

Thanks everyone for the input on resolving this electrical nightmare.
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Unread 09-29-2014, 01:29 PM   #15
bigjoe
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Glad to hear you solved it. Of course the Jeep will give you an other issue before you know if it's like mine.

Keep us posted on her and good luck.
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