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Ignition/Electrical Short...??????

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Ignition/Electrical Short...??????
M

mycj7

Jeeper
Posts
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Location
California
Vehicle(s)
1984 Jeep CJ-7 Scrambler, 4.2L, Manual, 6 cyl
I just replaced the temperature gauge today in my 1984 Jeep CJ7 and was very careful to put everything back as it was. I read lots about being careful because of grounding issues. It worked great and then I drove it. I drove about 2o minutes on the freeway and then got off at an exit and it shut down. I could then turn the ignition but it would not start. Yes there is fuel. The temp and fuel gauge are now pegged to the left (dead I assume). The lights, stereo, and voltmeter all still work. I would assume it has to be some kind of short.... but where and how do I find out and fix..??? Any thoughts?? Thx
 
First thing would be to check the fuses then go to the fusible links coming off the starter relay. The coil attachment clip is a known troublemaker, it should be replaced or at least checked. The best thing would be to replace it with a coil that has screw on connectors.
 
Confirm the engine cranks with the starter but doesn't 'lite' up. Is that correct??
First- Put 5gal of fuel in the tank.
If the engine doesn't 'crank'-Most likely the alt. died and it therefore could not recharge the battery.
LG
 
Its definitely not gas. I have gas in it. I will check the fuses. But why did it bow in the first place. Of course I woke up at 3 am thinking about this stupid thing!!
 
Please be specific. Will the engine turn over? It turns over but doesn't start? Does it have spark? Can you roll/push start it?

If it 1 - turns over. 2 - Doesn't have spark. 3 - Will push/roll start. It is likely that while pulling on the wires while working on the temp gauge you partially pulled out a wiring plug. get under the dash and check your wiring loom plugs for tightness.

If you aren't getting any power to the ignition circuit you could have shorted the jumper between the fuel gauge and the temp gauge shorting out a fuse somewhere.
 
mycj7 said:
Fuseable links......please explain and tell where they are??
Click to expand...

There are two fusible links coming off the hot side of the starter relay. They are pretty much a slow burning fuse. They can be checked by pulling on them to check for stretch also with a voltmeter. The wonderful internet has info on these. You seem also to have issues with the temp/fuel gauges, John Strenk is the authority on those:The new Gauge Page
 
Hedgehog said:
Please be specific. Will the engine turn over? It turns over but doesn't start? Does it have spark? Can you roll/push start it?

If it 1 - turns over. 2 - Doesn't have spark. 3 - Will push/roll start. It is likely that while pulling on the wires while working on the temp gauge you partially pulled out a wiring plug. get under the dash and check your wiring loom plugs for tightness.

If you aren't getting any power to the ignition circuit you could have shorted the jumper between the fuel gauge and the temp gauge shorting out a fuse somewhere.
Click to expand...

I was driving it when it quit. It shut down as I was driving from a the freeway. It turns over but won't stay on. I don't think it will roll/start. I will look at wiring loom but its like a jungle as you know.
 
spark test wouldn't hurt and is easy
last thing you did was replace gauges? i would check all fuses and relays to see if short popped one of them.....relays you cant visibly see but you could make a jumper and test
 
mycj7;21573 It turns over but won't stay on.[/QUOTE said:
:confused:
The engine will 'crank' when you turn the key, is that correct?
What do you mean by "won't stay on"? Does it start and then when you release the ign key the engine stops running/dies??? Describe in detail.

LG
Click to expand...
 
As Lumpy said. Please describe in detail. Imagine that we weren't there and you have to explain exactly what happened/happens. The details really do make a difference or at least easier.
 
OK.. so I found the Ignition Fuse blown. Just replaced it and turned it over with no success. Looked and the Fuse was blown again. No need to figure out the cause. A side note that may help someone figure this out for me.... As I pulled the key out, I felt a very small rumble. I then tried to start and no "very small-but noticeable" rumble. So I did it again went to remove the key and felt the rumble again. Another side note--- my next project was going to be replace the ignition switch because I think the tumbler is broken on current one since I have to play with it and the knob on the column to get it to stay in the lock position. Any ideas......????? Anyone ever replace the ignition lock?? Not sure how how it will be to pull steering wheel, etc.
 
You are blow'n fuses, and you state "No need to figure out the cause". WTH- You have a potential electrical fire on your hands.:confused:
Disconnect the battery, ASAP...............
LG
 
The culprit has to do with the red wire to the fuel gauge....Any ideas
 
Looking at a wiring schematic for my '86, That red wire goes to the ignition switch, ignition control module, hot wire to the coil, and alternator. Better trace that down.
 
If it were me I'd pull the wire off the speedometer and give her a test. I bet the gauge is fried. The gauge supplies a pulsed power output to the other gauge. All it takes is a blink at the wrong time to fry the tiny wires in the gauge.

Changing the cylinder isn't all that difficult, but if you have an adjustable steering column you should replace the bushings as well. You might be surprised to find out that the real power switch is behind the dash controlled by a wire running under the steering wheel column covers.
 
Hedgehog said:
If it were me I'd pull the wire off the speedometer and give her a test. I bet the gauge is fried. The gauge supplies a pulsed power output to the other gauge. All it takes is a blink at the wrong time to fry the tiny wires in the gauge.

Changing the cylinder isn't all that difficult, but if you have an adjustable steering column you should replace the bushings as well. You might be surprised to find out that the real power switch is behind the dash controlled by a wire running under the steering wheel column covers.
Click to expand...

I am sure you are right.. the temp gauge and the fuel gauge are fried.. still want to find out why it is frying. Im going to pull the gauge again tomorrow and look at the gauges.
 
There is a procedure for working with the gauges that absolutely HAS to be followed, if not, you fry your gauges. Never let 12v power touch the power side of, I think it's the fuel gauge or is it the temp gauge..... Hmmm can't remember while sitting here. Power goes into one gauge, goes through a small transformer and is reduced, pulsed power comes out that powers the gauges. These gauges are well known for their lack of electrical understanding and will pop in a second.
 
I bought new gauges and tested the old ones. One of the posts was making contact and was shorting out. The new gauges have been installed and work great!!

Thanks
 
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