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post #1 of (permalink) Old 01-12-2005, 08:05 AM Thread Starter
 
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no ignition electrical

the search function is causing me grief, but i found a couple of places to start with this...i'm looking for a little more direction here...

last night, i was driving along a city road at city speed, doing nothing...didn't hit any switches, brakes, or anything else...all of a sudden, the dash went dead, fan off, radio off, engine dies...coast to the side of the road, figuring it was my wiring for the nutter bypass which failed (crimped on spade connectors)...turns out one crimp was working its way out, but ultimately this was not the problem...i re-connected the wires and tried to fire it up, and nothing happens when i turn the key. nothing...well, not exactly nothing - i can hear a relay clicking when i turn the key...headlights are bright, and interior lights work, but no ignition electrical at all...fuses are all tickety-boo...

my 90 YJ 258 was nuttered about a year ago and i did the TFI swap (coil, cap, rotor, but not the module) last spring, with no problems until now...i didn't think to check the coil or module to see if it was hot at the time...

any ideas?

burned out ignition module?
fried ignition switch? (where exactly is it, BTW?)
relay somewhere?

it was towed to the local jeep hospital (a friend's garage)...we'll be taking a look at it tonight...

thanks all...
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post #2 of (permalink) Old 01-12-2005, 09:02 AM
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Re: no ignition electrical

Look at the single points of failure first, note that all the circuits come off the starter solenoid.

Start by looking for power before and after the fuseable links, also look for a completely bad negative wire from the battery to the engine block/frame. Of couse.. .check that battery as well.



Last edited by LEVE; 03-24-2009 at 07:44 PM.
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post #3 of (permalink) Old 01-12-2005, 09:15 AM
 
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Re: no ignition electrical

I doubt if it's anything to do with the ignition. It sounds as if you lost all power so as LEVE said. Start testing at the starter solenoid. It will be the post were the battery cable connects. And check all your ground cables.

You didn't mention that the headlights whent dead but that the dash engine and other things died so you might have the problem a little further down the wire.

The ignition switch is a good idea to check. I don't think you could loose that many circuits on the fuse box at one time.

If I knew a little more about a YJ I could help you a little more.
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post #4 of (permalink) Old 01-13-2005, 02:44 PM Thread Starter
 
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Re: no ignition electrical

update...

the grounds (engine-battery and body-engine) are fine...

ig. switch checks out ok (though it may not by the time i'm done with it when i have to put it back on the column!)...

i'm told (i wasn't there when it was checked yesterday afternoon) that the hot (red) wire is ok from the battery to the snakepit of a distribution block (my heep doesn't have one of those fancy-dancy power distribution centres, nor a starter relay which any of us can find) and from there up to the back side of the fuse block on the firewall, suggesting that it's something between the fuse block and the key...

haven't tested the starter solenoid, but the wiring to it from the battery is fine...have to double check the green wire to the snakepit...

will also be taking the fuse block off the firewall to take a look on the back side of it and see if anything is misbehaving...

looking back, i had this happen just before christmas - driving along and everything went dead, then came back 1-2 seconds later...i knew it wasn't right and should be looked at, but it didn't happen again, and i forgot about it...besides, what fun trying to trace down an electrical problem that happened once, but is just fine now!
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post #5 of (permalink) Old 01-13-2005, 03:20 PM
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Re: no ignition electrical

The suggestions above are good ones. The Solenoid is a great place to start troubleshooting this type of no-start condition, but I would think there would have to be a string of peculiar circumstances for solenoid failure to force an engine to stall all by itself. I think Ignition Switch failure is more plausible given the description of the symptoms. Of particular interest is that you have a no crank condition, though your battery appears healthy by your description of headlamp strength with the key in the START position.

[ QUOTE ]

burned out ignition module?
fried ignition switch? (where exactly is it, BTW?)
relay somewhere?


[/ QUOTE ]

Short of a critical failure that could potentially traumatize the wiring at the bulkhead firewall connector (or somewhere else along Ignition primary), the ignition module can't create a no-crank condition by itself. I would diagnose that before worrying about spark, which the ignition module can control.

The ignition switch can kill a running engine and keep it from cranking if it has come loose or failed altogether.

Relay? The Starter Solenoid is the best place to start looking, though, like I said, it's a stretch to believe that it forced a stall by itself, though it can sponsor a no-crank condition. I'm unsure of any other relays the YJs may have come equipped with, you may want to think about a wiring diagram. DArksiderz have some for your year here:
http://www.darksiderz.co.uk/reference/Engine_4.2.pdf

Looking at a snippet of the diagram,



It looks like you may want to check and see if the starter solenoid is getting signal on the GREEN wire when the key is in the START position, if not look at the Starter motor relay (perhaps replace), and then work your way back to the ignition switch from there if there's no signal. Either way, you can't worry about idle if you can't even get it to crank, so I would start there if I was you.

Of course it might help if I owned a YJ, but it's not that far removed from a late CJ.
post #6 of (permalink) Old 01-14-2005, 08:09 AM Thread Starter
 
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Re: no ignition electrical *UPDATE*

turned out to be a blown fusable link from the starter relay (which didn't look at all like any relays i've seen before)...we repaired the blown wire, only to find out that it blew because of a short under the dash somewhere...now, a good part of my under dash harness is a melted mass of plastic and copper, and a few wires under the hood need to be replaced as well...

can anyone tell me if there is:
1) a difference between the wiring from 88-90 (258, carbed)
2) a difference between the wiring under the dash for an auto (mine) and standard (potential donor)?

i was really hoping it was something easy, like a switch or relay...i don't like it when fuses or links go, because the usually go for a reason, but finding that reason can be a huge PITA...
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post #7 of (permalink) Old 01-15-2005, 10:36 AM
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Re: no ignition electrical *UPDATE*

[ QUOTE ]
we repaired the blown wire, only to find out that it blew because of a short under the dash somewhere...

[/ QUOTE ]You never repair the wire with another length of wire... I hope you used a new fusible link or a shaved piece of wire to duplicate the link. If not, there was no protection from the shorting condition and all the power from the battery was available at to the short... hence the melted harness.

[ QUOTE ]
i was really hoping it was something easy, like a switch or relay...i don't like it when fuses or links go, because the usually go for a reason, but finding that reason can be a huge PITA...

[/ QUOTE ]

Well, it's time to face your worst fear...

Here's what I'd do... First remove the positive lead from the battery.

Repair that darned fuseable like correctly.

Find on the schematic which circuits it feeds... Identify each one of them! Pardon the electric pun, but knowledge is power!

Then isolate the section of burned wiring. You'll be able to see the wiring where it's not melted. Carefully remove the melted mass to reveal the wiring INTACT. You should be able to identify what wire goes where by following it to each end of the unburned sections and matching the insulation covering. Once that's done, cut the bad wiring out, solder in NEW wiring, of the same insulation color, if possible, and cover over/insulate the solder joints. Repeat this for each wire.

With a little patience, you'll be able to pick out the wiring and repair each circuit.

Now that the wiring is repaired it's time to hunt for the short...

Put an Ohm meter on the lead to that fuseable link. Next, start removing items that it feeds. When you no longer have a short indicated by the Ohm meter you've found the right item causing the problem.

My bet is that the problem's cause by a high current device that's been damaged by water/moisture pouring into the dash area under the windshield cowl or fresh air vent.
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post #8 of (permalink) Old 01-15-2005, 01:44 PM Thread Starter
 
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Re: no ignition electrical *UPDATE*

i managed to find a new dash harness for a reasonable price, and will have it tomorrow...we're just going to replace the whole thing from the fuse block back...

as for the wires under the hood we're going to do just as you suggested leve...

last night my wife asked me when enough is going to be enough for me to just get rid of this thing and get one more reliable...i started thinking about it, and unless the frame breaks in half, everything else is salvageable...as my friend puts it - "i know a guy who's got a tool that might be able to do something about that"...the thing is paid for, so a couple hundred bucks a year is a pretty low price to pay, plus the sense of accomplishment and contentment i get working on it (as frustrating as it is sometimes)...she just rolls her eyes and shakes her head sometimes, then grabs the ratchet and follows me out [img]images/graemlins/grin.gif[/img]
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post #9 of (permalink) Old 01-15-2005, 01:55 PM
 
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Re: no ignition electrical *UPDATE*

She helps you? You lucky dog.
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