86 Cherokee. Need desperate electrical help!!!! plz

I have a Physics degree, I studied Electrical Engineering for four years in graduate school, and I have done lots of house wiring too, but I have a horror of automotive electrical systems. There is just something, about driving down a winding country road, with no moon, and having all the lights go out at once. I can't forget it, not even thirty-five years later. It would have been worse, had it been night time!

You do not have a bad ground. What you have, is the wire to one of the park or interior lights shorted to ground. Unplug the connector from the back of the light switch. Using a continuity tester or an ohm meter, figure out which of the connections to the switch has zero or very small resistance. Trace from that connection to the point where there is a wire, with its insulation skinned off, contacting part of the vehicle body. It may also help to unplug the marker and park light bulbs, and test the bulb socket for evidence of a short. If your interior light is part of the same circuit, it may also be the problem.

Earle

*** Free account sponsored by SecureIX.com *** *** Encrypt your Internet usage with a free VPN account from ***

You are describing ground theft.

There should be a wire mesh cable running from the engine block to the firewall.

On some there are computer grounds bolted to the inside firewall just above and to the right of the gas pedal. The rest of the computer grounds should be bolted to the engine block by the oil dipstick.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail >

Hi all its me again.

I pulled the instrument panel out none of the bulbs seem to be shorted I tried a new fuse with the instrument cluster out and pulled the headlight switch and it still blows a fuse. Where are all the grounds at for the parking lights, all of them seem to run back into a black wire!!!!! Nothing that I have found ties it back into the frame or the battery for an actual ground. How do I work an ohm meter I have one and when I touch say the red probe to the blue wire which would be the parking lights and then to either the body for a ground or the black wire coming out of the back of the headlight switch, I get a reading of either.008 or .002. and it beeps at me???????? Does this mean the circuit is good or bad??? I pulling my teeth out cause every time I turn around I find something else wrong with this jeep, its all mostly mechanical stuff so no prob, but this electricity stuff I'm almost clueless, and to top it all of it looks like someone has screwed around with the wiring......bad. Like 4 black wires that run from the signal lights (I believe), the marker lights and 2 other sources run in a plastic flex tube and are soldered to 3 black wires then it was wrapped in Duct Tape!!!!!!! I need desperate help and please feel free to go into depth with things. This is driving me crazy................ Literaly

Sincerely

Dave

Oh yeah I did find the main ground coming off the back off the block to the firewall, it looked ok but I took it off and cleaned it up just to be sure, I did this before I tried the new fuse with the instrument gages out, no luck.

Dave

For starters I would get that radio out of there and then see what happens.

Mike

Dave G wrote:

The duct tape is from the factory, all the Jeep harnesses I have seen use it here and there. Seriously...

I think the radio that the OP said killed the battery, which is why it was out in the first place, is the trouble. I think he will find his short there.

Mike

Earle Hort>

***

There are many different brands and models of ohm meter. I assume that you actually have some kind of "multimeter" with volts, ohms, and amps scales. I suggest that you read the manual that comes with yours, from start to finish. This will not only have the effect of familiarizing you with the meter, but it may calm you down and make all that electricity less scary. For this kind of work, you will want to put the meter on the lowest ohm scale that it has.

Mine is a Suntool multimeter with a 1-200 ohm scale, that has a beeper on that scale. Beeping indicates a dead short, and yours probably is the same way. The higher scales, like 100-20,000 ohms, etc., are useless in this application.

If you are getting readings of 0.002 or 0.008 ohms on the parking light circuit, or beeping for a dead short, then chances are good that you have a dead short to ground, in that circuit. Black wires are usually ground in an automotive application. Do not try to apply this to, for example, house wiring, or you are likely to give yourself a nasty burn.

In a case like this you will better off, unwrapping all the parking light wires, including the grounds. I'll bet someone has wired one of the feeds or 12 volts directly to ground. At the least you will want to get rid of that duct tape and replace it with proper electrical tape. Now just because a wire is black, that does not mean it is a ground. The previous owner might have replaced the parking light wires, which you say are blue, with black, just because the local Radio Shack or automotive parts store happened to have black in stock. Although the most likely place for a short is in the wiring, it is also possible that one of the light sockets is shorted internally.

You should be able to buy blue wire, black wire, and parking light sockets of the proper type, at your local auto parts store. Sometimes, it is more effective to replace the whole circuit, than to try to track down the short.

Earle

*** Free account sponsored by SecureIX.com *** *** Encrypt your Internet usage with a free VPN account from ***

Maybe the instrument panel light inside the radio?

Earle

***

*** Free account sponsored by SecureIX.com *** *** Encrypt your Internet usage with a free VPN account from ***

Seeing as that one is usually tied into the park light circuit, it made it my guess.....

I first thought the radio was acting as a ground for the wrong thing, but didn't say it well....

Mike

Earle Hort>

***

Even with the radio out it still pops a fuse the radio is an aftermarket one that doesn't use the same harness. I noticed that there are 2 harness one was cut off with new wires to go to the radio and the other one is just dangling there it does not go into the radio, that harness had the black ground wire snapped, but I doubt this could be the problem. I did reconnect it though. I'm really stumped would it just be either to hard wire it from say the battery with an inline fuse on the hot side, and running it to all the parking lights, and connect it to a toggle, but then I would have to figure out a way to light the interior this is driving me insane, does anyone have any waring harness diagrams and locations and such I have a lights diagram but it sure is not very helpful.

Dave

It sure sounds like a dead short. The meter was beeping on the power line to the lights which meant short. Have you checked all the bulbs on the circuit?

Does the sucker have a trailer hitch? The wires for that can short out.

I have the factory wiring diagram for an 88. I could email it if it might help.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail >

You know.....

He says everything was fine until he installed the radio and oh by the way there is a rats nest of suspect wiring and lose wires hanging about and there are wrong size fuses installed..

After checking the first suggestion of bad grounds that did not pan out common sense would suggest that he remove the radio.... the problems did not appear until this 'used' radio was installed that the previous owner advised was not working properly

Mike advised him to remove the radio and he took the dashboard apart looking for additional bad grounds and found nothing.

Then he started playing around the an ohm-meter he admits which he doesn't know how to use and adds that " it looks like someone has screwed around with the wiring.....bad" and "I need desperate help and please feel free to go into depth with things."

Okay Dave ... you have heard of 12 step programs for alcoholics and addicts and we have a 12 step program for this situation also

Step 1: Remove the radio, copy or photograph the diagram stamped into the case that says what wire goes where. Step 2: Smash the radio with a sledgehammer to prevent you or someone else from installing it in this or any other vehicle. Step 3: Throw the bits away Step 4: If the Jeep will start and the electrical components that worked before work now say a prayer and go to you local community Fish Fry for dinner.

If you really want a stock radio:

Step 5: Read the instruction book on the meter. It may be a Volt-Ohm meter or Volt-Ohm-Amp meter.. In any case wander around the house testing the various AC plugs and batteries you find. . Step 6: Test your vehicle battery for voltage, test your battery voltage with the headlights on and off, check with the car being cranked. Step 7: Check your main grounds for resistance. There should be three. Battery to body which is usually behind the battery, battery to engine block, and cylinder head to firewall which is usually a mesh strap connecting a valve cover bolt near the rear to the firewall diagonally across from it. Step 8: Take all these grounds apart and wire brush or steel wool them until they are shiny. Please note that these grounds have a nasty habit of rotting from within Step 9: Check the wiring diagram from step 1 and using your meter check the voltage in the radio wiring pigtail. Make sure it is 12v and that the hot is hot and the ground is ground and not switched. Check with the key on and the key off. It should have power with the key on and no power with the key off Step 10: Procure a matching or compatible Jeep Radio that works Step 11: Install it Step 12: Enjoy...

Dave,

Did you change ANY of the connections on these two sets of wires? What did you "reconnect"?

Are they having catfish, or cod? Because I really like catfish, but I am not so keen on cod.

Earle

*** Free account sponsored by SecureIX.com *** *** Encrypt your Internet usage with a free VPN account from ***

The church dinners around here usually serve Cod. Catfish fresh from the lake is always nice in the summer.. pix: 57

Nope it does not have a trailer hitch. The Fuse still pops with the radio un plugged. The night I drove the vehicle with the headlights on the radio was plugged in sitting on the passenger seat it was just not mounted in the dash. Again I don't think the radio is the problem cause even with it un-plugged it still blows a fuse. The only thing I can think of is a dead short but, how would I isolate it with the meter to know if its screwed up in the front or in the back. Like I said before I'm not good with elecricity. This is the first time I've encounter these kinds of problems, I never had these problems before in any of the previous vehicles I've owned. Heres a few pics to show you guys some of the things I'm talking about, and dealing with.

Pic 1 is of the wire on the radio harness "That is not used" and of where the wire was cut and my repair job.

Pic 2 is of the wiring harness that is used and the one that is not used.

Pic 3 There is an orange wire that is coming off of a part I have no idea what it is. The wire is real thin and oranage and ends at nothing next to my gas pedal.

Pic 4 Here you'll see where the orange wire from pic 3 ends up and does anyone know what that connector is by the gas pedal? It has 3 black with white stripes going into it, it breaks off from the main harness that goes to the computer?

Pic 5 Is My Nightmare!!!

Thanks you all for the help and thanks for the ridicule (I'm glad some people finds this ammusing) I'll figure it out, some way.

Sincerely

Dave

Does your oil pressure gauge work?

I think you need to stop and go back to the basics.

It was working fine before you decided to 'fix' broken wires and put the radio back in. Correct?

Therefore I highly recommend you stop trying to look for more trouble and go back and unfix 'every' connection you taped up or re-connected because it 'looked' right or was cut. The cuts could be related to the radio plug.

Some radio harnesses mate up power lines in the plug before they go into the units and some split up lines inside the plug where you can't see. This is for radio lights, memory, antenna, ground and power. That cut line might have been a dead short that you connected back up.

You 'know' you have radio or radio harness troubles because it used to kill the battery when the radio was plugged in, 'BUT' you said it was wired wrong so you fixed it... You need to un-fix it.

You have already pulled out 'all' the park circuit and dome light bulbs, right? That totally eliminates them as suspect. Therefore it is likely under the dash. The bulbs do internally short sometimes.

The orange wire is the oil pressure sender wire.

The last couple wiring nightmares I personally had dumped in my driveway were both a case of bad fixes causing more headaches. I had then remove their fixes and bingo we found the troubles using my multimeter on volts.

The fact that you pop a fuse as soon as the switch comes on makes it harder to track down.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail >

Trust us, Dave, it *is* the radio harness. Not the radio, not the parking lights, not the dome lights, just the harness.

Resist the temptation to Mickey Mouse some sort of toggle switch to make the parking and dome lights work. You'll forget and leave them on, resulting in a dead battery, or you'll forget them and leave them off, resulting in the person who rear-ends you being all dead-like and your arse in jail. Not to mention the fact that you'll be leaving a problem under the dash that could result in a fire in your lap.

Stop worrying about the grounds for your parking lights. Once power gets past the bulb you don't care (right now, anyway) how it gets back to the battery. That's just looking under the wrong rock.

Your brake lights and signal lights are on a different fuse, that's why they work and your parking lights don't. Your headlights are protected by a circuit breaker, that's why they work with the fuse blown. Your parking lights are probably on the same fuse as the dash lights (a feature to let you know when you don't have tail lights). Something in the radio harness is tying the dash lights to ground, popping the fuse and taking the parking lights with it. It isn't the bulbs.

Here's a very brief primer on automotive electricity:

(-) (+) [Ground]-------[ ]--------[FUSE]-----./ .-------@-----[Ground] [ BATTERY ] Switch Lamp [ ]

And here's what you've got:

(-) (+) *POP* [Ground]-------[ ]--------[FUSE]-----./ .--+----@-----[Ground] [ BATTERY ] Switch | Lamp [ ] | \[Ground]

If power gets to Ground before it passes through the load (a lamp, motor, whatever), the fuse should pop. If the fuse doesn't pop the wire gets hot, melts the plastic and starts a fire.

IIRC there's a ground wire in the factory radio harness. Hazy memory suggests that one side of each of the speakers _might_ be at ground too, so you've got lots of possibilities. Plus what ever non-standard hack the previous owner did to fark it up in the first place.

Do as Mike suggested: Undo as many of *your* wiring repairs to the radio harness as you can. Don't trust the aftermarket radio harness color code to match the factory color code. You can buy a "universal fit" aftermarket radio harness at your local AUtoZone or other chain retailer that should come with a color code chart that will tell you which radio wires do what.

Come to think of it, don't even trust the solid color codes you see in the XJ's harness, who knows what the previous owner did. Figure out which ones are speaker wires (using the key from the new harness) and connect them to the radio harness. Using your meter, _test_ the remaining wires to make sure it is fed voltage from the fuse that it should be fed by. Fuse in: power. Fuse out: no power. There should be two hot leads, one controlled by the keyswitch, one not. Accept no substitutes. Leave the dash light and power antenna wires out of the mix, cap both ends of the wires.

Let us know how you make out.

Dave G wrote: