ZJ electrical problem

Doc34 · 07-15-2012, 02:00 PM

My wife drove our 95 ZJ to see her uncle and stopped for a soda on the way. She was only in the store for 3 minutes and came back and turned the key. Nothing. No dash lights, interior light or anything. Completely dead.
Could the battery go to 0 that quickly? It's only 1 1/2 years old and was charging normally.
Other than the starter, where does the positive cable go that provides power to the rest of the Jeep? I know a broken, loose or shorted cable would be a likely suspect. It just seems odd that it would happen so fast with no warning.
Any suggestions?
Thanks

Nejeep · 07-15-2012, 02:13 PM

Yes a battery can die that fast, but see if it jump starts ok. If it wont jump start then you have other problems, bad connection or cables.

KoreaZJ · 07-15-2012, 03:45 PM

Measure the battery voltage at the terminals, is it near 0v?
If not, there's a bad connection.
Clean/tighten battery cable connections. Check for damaged cable.

SKorch630 · 07-15-2012, 05:09 PM

Also make sure the posts and connectors are NOT corroded. A simple battery terminal cleaner and a brush will be perfect. All < $10 and you're good. I'll post a picture of the stuff I use in a bit.

afinley92 · 07-15-2012, 07:54 PM

May be a duh, but Check the alternator? Or starter fuse?

Doc34 · 07-16-2012, 05:28 PM

All of the wiring seems to be good. Nothing loose or corroded. Battery terminals clean and shiny. Jump starting works and the engine runs fine but when shut off will not restart. All power for lights, gauges, radio, etc is gone. Fuses are all good. Battery voltage is at 12.1 volts.
I tried a new battery and it started fine but when shut off will not restart. New battery voltage is 12.5 volts when not running and 13.2 volts running. I am not sure how to check the alternator for proper charging.
Is there a master relay that would kill all of the power when not working right?

ZeeJay1997 · 07-16-2012, 07:12 PM

The static and running voltages are about 1/2 volt low. That shouldnt cause your sysmptoms though.

B+ runs to starter, alternator, and the PDC (box behind battery)

After you have checked the voltage to the input terminal of the PDC, pull all the fuses out, check them, and clean the legs. Verify that when the switch is on, you get battery voltage to all fuses. One of the small fuses is the Key On fuse.

DeansWings · 07-16-2012, 08:04 PM

On my ZJ, if the terminals are too tight it will not work. I will get juice until I try to start then it loses the connection somewhere. I can flick the lead with my finger and it regains it's connection. It's the weirdest thing as there is no corrosion what-so-ever. So try loosening and jiggling. I smack mine with a wrench/screwdriver/shoe from time to time... just to keep things fresh.

Canyon411 · 07-16-2012, 09:59 PM

Normal alternator voltage while running is from 13.8 to 14.2 and (as mentioned above) you are low but not that much. Are the cable ends for both neg and pos factory or parts store specials? Check the neg cable where it grounds to the fender and make sure those connections are clean and tight as well. Possible ign switch issue?

You mentioned that once it starts and then is shut off, it will not restart ... what does it take to get it restarted after that happens?

Doc34 · 07-17-2012, 09:13 PM

It restarts when jumped. All wiring and connections checked and good. All fuses checked and good. I put the battery in my other car and it stars it fine so it's not the problem. The problem is when the key is turned to start everything goes dead unless being jumped. If the ignition switch was bad a jump wouldn't work. Time to give up?

KoreaZJ · 07-17-2012, 10:27 PM

When you jump start, are you connecting the NEG cable clamp to your Jeep battery NEG terminal? Or chassis ground?

Bob Pearce · 07-18-2012, 05:25 PM

I used to have a similar problem which I called my "Harry Potter" problem. I got the vehicle started by tapping the solenoid or starter with a spanner and concluded that something was sticking in there. It was very random, but one day I bit the bullet and removed the starter. It was full of grease/carbon and had obviously been getting worse for a long time. Since cleaning and replacing have not had a problem. Just build up over a very long period.

Canyon411 · 07-18-2012, 07:23 PM

I could see a dirty/bad solenoid preventing the starter (and engine) from cranking over, but once the key is released and springs back into the run postition, the op should have power to instrumentation and interior lights, etc. From what I understand, there is a total loss of power when the key is put into the start position and it does not resume until the vehicle is jumped.

Doc34 · 07-20-2012, 04:57 PM

Quote:

Originally Posted by Canyon411

I could see a dirty/bad solenoid preventing the starter (and engine) from cranking over, but once the key is released and springs back into the run postition, the op should have power to instrumentation and interior lights, etc. From what I understand, there is a total loss of power when the key is put into the start position and it does not resume until the vehicle is jumped.

Your understanding is correct. No power at all after the key is turned to start.
Only a jump will start the engine and all systems, lights etc. are normal till the engine is shut off. There is power when the key is in the run position but when turned to start then all power is gone and won't come back.

Canyon411 · 07-20-2012, 05:46 PM

Quote:

Originally Posted by Doc34

Your understanding is correct. No power at all after the key is turned to start.
Only a jump will start the engine and all systems, lights etc. are normal till the engine is shut off. There is power when the key is in the run position but when turned to start then all power is gone and won't come back.

I know you said the battery is known-good, but what you describe sounds like a failed/shorted battery. When it's jumped, the jumper cables supply power to your battery cables thru direct contact. When the jumper cables are removed, your alternator takes over once the vehicle is running. As soon as it's shut off, the battery is shorted and did not receive any of the charging energy from the alternator. (Lets go along with this theroy for a moment)

You said that once the vehicle is turned off (after being jumped) you can turn the key back to "on" but as soon as you turn the key to start, everything goes black.

Try leaving the jumper cables on and connected to the second vehicle. Put you key in the run position and verify power to instruments, etc. Now start the vehicle. Let it run for a bit and then turn it off. Now go back to the key in run position and see if you have power right away as if nothing is wrong. If you do (even though this battery starts another car just fine) I would be very suspect of it for having a dead cell or three.... Enough for low current draw but falls on it's face when you attempt to draw high current.