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Electrical issues when *attempting* to start...

Dvipercop

Dvipercop

NAXJA Forum User
Location
Washington D.C.
Ok, here's the deal. I go out tonight to start my Jeep ('92, 4.0I6 auto, AW4, etc.), put the key in the ignition and turn. Nothing. You may be thinking, "Hmmmm, sounds like the NSS". I will personally fly to your house and shoot you if you say that. Sorry, really pissed right now. Anyhow, not only does it not crank, click or anything, but the lights don't work either. The battery was replaced about a month ago, and currently reads 12.54v according to my voltmeter. There was some corrosion around the positive terminal, so I took it off and cleaned everything till it shined. Still nothing. I'm not sure where to begin to check...

The starter and alternator were both replaced about a year ago, and up till tonight, worked perfectly. Since it was dark and freakishly cold out, I didn't have much time to test all the voltage. What makes me so bewildered is the fact that I have no electrical. Nothing at all. Yet the battery and terminals are both functioning and read the correct voltage. Could this have something to do with the PDC? Perhaps corrosion there as well? But if that were the case, why doesn't the engine even click when I try to start it?
 
Did you check the NSS........sorry I had to. How are the grounds? Have you checked the fuse's in the PDC? Have a wiring diagram for a 91' if you need it.
 
So you have 12v accross the battery, no lights and no reaction to turning the ignition key. Sounds like bad ground from the battery. Trace the + battery cable to the starter relay and check for 12v. As a start, check the ground cable to the block using an ohm meter. There could be corrosion inside the crimped fittings that you cannot readily see.
 
This definitely sounds like a cable and terminal issue. Test the voltage between the positive terminal and the engine block, and from the positive terminal to the chassis. If no go, look at your grounds. don't neglect the strap from firewall to valve cover, which can corrode to dust while still looking fine. Some of those points can look good and be bad. If the grounds pass, then test the voltage between the negative terminal and successive points in the positive cable path: starter relay to starter itself. Somewhere you'll find the fault.
 
Also, there should be a start relay in the PDC (Bosch/Hella/DIN type) that may have gone south on you. It should be marked on the lid - I have neither a 1992FSM nor a scanner, so I can't help you more directly. However, that's what it sounds like to me (considering your opening comments, I'm going to assume you've had a good look at your NSS. I'm in no hurry to get shot again...)

5-90

Remember, a DIN relay has a fairly soft click, so you may not hear it with the hood down and the windows up. You'd need a helper to turn the key while you listened to the PDC yourself, I'd think (I have a few down by my right knee, and I can't hear them when I turn the key on. They're for power distribution...) - Ed.
 
Ok, so I had another run at it tonight, taking in all the suggestions posted. It appears (according to my voltmeter) that all grounds are functioning perfectly. There is plenty of power going to the PDC and all blade fuses in the PDC are fine. Here's my next set of questions:

Does any one of the relays in the PDC have the ability to completely cripple all electronics on the XJ? I.E. no lights, no start, nothing.

Are there any fuses under the dash that could do the same? Or is there a combination of fuses that could accomplish this goal?

I had my mom try and jump my Jeep just for sh*ts to see what would happen. I hooked it all up and left it for about a minute. I tried my lights and they came on for about 10 seconds then went dead again. After that I also tried to start my Jeep. All that happened was a faint click and then absolutely nothing. Any other suggestions out there? I'm open to anything. If I can't get it figured out by Monday, I'm towing it up the mechanic to let him deal with it. I've come pretty damn close to breaking several objects with-in arm's reach while trying to figure this out.
 
Dvipercop said:
Ok, so I had another run at it tonight, taking in all the suggestions posted. It appears (according to my voltmeter) that all grounds are functioning perfectly. There is plenty of power going to the PDC and all blade fuses in the PDC are fine. Here's my next set of questions:

Does any one of the relays in the PDC have the ability to completely cripple all electronics on the XJ? I.E. no lights, no start, nothing.

Are there any fuses under the dash that could do the same? Or is there a combination of fuses that could accomplish this goal?

I had my mom try and jump my Jeep just for sh*ts to see what would happen. I hooked it all up and left it for about a minute. I tried my lights and they came on for about 10 seconds then went dead again. After that I also tried to start my Jeep. All that happened was a faint click and then absolutely nothing. Any other suggestions out there? I'm open to anything. If I can't get it figured out by Monday, I'm towing it up the mechanic to let him deal with it. I've come pretty damn close to breaking several objects with-in arm's reach while trying to figure this out.
Click to expand...

yeah that right there tells you it is either a bad battery or a bad connection.
 
gopher_6_9 said:
yeah that right there tells you it is either a bad battery or a bad connection.
Click to expand...

That's what I thought at first as well, but the battery is fully charged and all connections seem to be working...
 
Dvipercop said:
I had my mom try and jump my Jeep just for sh*ts to see what would happen. I hooked it all up and left it for about a minute. I tried my lights and they came on for about 10 seconds then went dead again. After that I also tried to start my Jeep. All that happened was a faint click and then absolutely nothing. Any other suggestions out there? I'm open to anything. If I can't get it figured out by Monday, I'm towing it up the mechanic to let him deal with it. I've come pretty damn close to breaking several objects with-in arm's reach while trying to figure this out.
Click to expand...

Well, I'd say this definately points to the battery/charging circuit. Connect your mom's car as if going to jump but let it runs for 10 minutes or so to try and charge your battery. Then give it another shot, If the lights work, and it tries to crank (whether it starts or not), then your battery is dead. You could also temporarily swap batteries to see if your's starts.

It could have a bad cell and show sufficient voltage but not have enough amps to crank things up. You could have a charging issue that allowed your battery to drain.
 
5-90 said:
Also, there should be a start relay in the PDC (Bosch/Hella/DIN type) that may have gone south on you.
Click to expand...

exactly what i was thinking...

happened to my buddies YJ in the middle of a trail. we searched for the problem for over 2 hours when i finally suggested to check the relay. it wasny completely in contact with its dock. (if it went south it would be the same as not being in contact) once we pushed it back it, it started right up like it had been running the whole time.

id check that if it were me, its easy enough to check and its a quick fix if its the culprit
 
what are NSS, DIM, PDC?
I assume that they are involved in the electrical system because that is what this thread is about, but what do they do?

O and when I searched it said sorry there were no matches.
 
I had a real similar problem with my 89XJ. It would not start unless jumped and then would die when lights or anything electrical was turned on. I thought bad battery so I bought a new battery and same problem. The weird part is the part about all eledctrical going dead. When key is turned on everything works lights, relay clicks like it will start. When you turn key to start position everything goes dead, lights wont even burn till battery ground is removed and reattached then cycle starts over. Just guessing I removed the wires from the alternator, wala, everything works perfect, starts lights burn etc, of couurse the battery is not being charged. This jeep is at the deer lease so I havent been able to get in my shop to work on it. I assume the problem is a faulty alternator.
Randy
 
XJiggy said:
what are NSS, DIM, PDC?
I assume that they are involved in the electrical system because that is what this thread is about, but what do they do?

O and when I searched it said sorry there were no matches.
Click to expand...

NSS should be Neutral Saftey Switch. PDC, ???, Power Distribution Connector? DIM???? has me too?
 
TRB said:
Also, I monitored battery voltage while trying to start and it never changed. It held steady about 12.5V
Randy
Click to expand...

Although your battery voltage sounds low for a fully charged battery (should be about 12.96 V as I recall), it sounds to me like your problem is under the steering column dash area with the wiring harness and or key-ignition starter switch itself, or both. Nearly all relay control power, including headlights run through that wiring connector and switch. I have had the same problem with several cars and jeeps over the years and it was both the wiring harness connector and the Keyed ignition-starter switch that had both both corroded and then burned up & melted!


That said, the story about jumping it with your mothers car battery might indicate a bad battery (granted a weird very unusual internal fault in the battery). Only way to really test it is to swap out the battery with a known working battery.

Mike McGinness
South Houston, TX
 
Try this....Get underneath the rig and physically check the voltage going to the starter solenoid wire while a helper HOLDS the key to the START position. If you are getting 12+ at this wire then the starter or solenoid is the culprit, if not then the problem is in the wiring or NSS.
 
XJiggy said:
what are NSS, DIM, PDC?
I assume that they are involved in the electrical system because that is what this thread is about, but what do they do?

O and when I searched it said sorry there were no matches.
Click to expand...

NSS = Neutral Safety Switch. Passenger side of the transmission, looks like a quarter-circle

PDC = Power Distribution Centre - that big box underhood with all the fuses and relays in it.

"DIM" I shall assume is a typo for "DIN" - I don't recall the original German, but it translates to German Institute for Normalisation (kinda like NIST here.) "DIN-style relays" are all over in the XJ and MJ - they're those little 1" cube relays with either four or five terminals, and one of three internal arrangements. If you ask for a "Bosch" or "Hella" style relay at the parts house, you should get one (since Hella uses them in all their kits.)

"DIN" can mean different things, based on context. For instance, a "DIN head unit" is the standard size you find in most older vehicles (where they don't have knobs and pressbuttons - like in the REALLY old head units!) a "DIN and a half" is becoming more common - it's one and one-half times the height, and a "double DIN" is twice as high. I believe later XJs use the DIN and a half, while earlier ones use the standard DIN (break for that is probably 1996/1997, but don't hold me to it just yet...)

5-90
 
I have a fully charged battery too, but it barely turns the eng. over. Test good for voltage, but when you test it for cranking amps it fails.
If I put in a diff. batt all is fine.
 
TRB said:
I had a real similar problem with my 89XJ. It would not start unless jumped and then would die when lights or anything electrical was turned on. I thought bad battery so I bought a new battery and same problem. The weird part is the part about all eledctrical going dead. When key is turned on everything works lights, relay clicks like it will start. When you turn key to start position everything goes dead, lights wont even burn till battery ground is removed and reattached then cycle starts over. Just guessing I removed the wires from the alternator, wala, everything works perfect, starts lights burn etc, of couurse the battery is not being charged. This jeep is at the deer lease so I havent been able to get in my shop to work on it. I assume the problem is a faulty alternator.
Randy
Click to expand...

I dont mean to high jack this thread. It just seems like there is something in the system that can disconnect the battery from the power distribution.
Randy
 
yours is doin the same thing mine is.
 
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