No Juice to the coil/distributor

valhalla3 · #1 03-20-2006, 03:48 PM

Hi - I was convinced that my fuel pump was bad but right before replacing it I bypassed the fuel pump relay and checked the pressure and found out it was ok. Now it looks like there is some kind of electrical problem. The security system has come on during this problem but it doesn't stay on. I reset it with the key method on the tailgate. I am not getting any spark and it looks like there is no juice getting to the coil. The check engine light will not come on when you turn the key on either. I thought maybe the PCM was bad but I talked to a Chrysler mechanic who said they rarely go bad. He suggested checking the fusable links, and the crankshaft position sensor.

Does anybody have any suggestions? Does anybody know how or where I can get some test point information on the computer cable etc.???

Thanks!

Val

dksob81 · #2 03-20-2006, 04:17 PM

Well you were when thinking of the PCM, it is possible that the PCM is the problem.

The CHECK ENGINE light not coming on can only be caused by 2 things, CPS (CrankShaft Position Sensor) or PCM (PowerTrain Control Module).
- I would start with the Crank Sensor it is the cheapest and the most common of the 2.

bringselpup · #3 03-20-2006, 04:24 PM

Quote:

Originally Posted by valhalla3

I thought maybe the PCM was bad but I talked to a Chrysler mechanic who said they rarely go bad.

I'm not saying your problem is your computer but I would not agree with what Mr. Chrysler mechanic said either.

When I was getting prices to replace my PCM on one phone call after telling the woman my part number she says "oh yes that's a popular one we sell a lot of those" and then after some keyboard clicks tells me they are out of stock!

I would be nosing around that security system if I were you. There was a recent post about the purple box that has the beeper from the VIC in it. Someone replied that people yank them to keep the security system from arming when they lock their doors. The PCM is going to cut power to the coil if the alarm thinks you're stealing the vehicle.

You might try pulling that box and see if you can start the vehicle.

dksob81 · #4 03-20-2006, 07:21 PM

Yes the alarm would cut power to the coil to keep it from starting, but would not cause the CHECK ENGINE light not to come on as soon as you turn the key.

valhalla3, try this, turn the key to the ON position and leave it there for a few minutes, while watching for the CHECK ENGINE light. After a few minutes the PCM shoud get a signal from the CPS and illumimate the CE light and then you should be able to start the jeep.

When the CE light illuminates it lets you know that the Computer has run the initial diagnosis and everything checks out and will allow the engine to start, when the CE light does not appear it is because the PCM does not recieve a signal from the CPS (bad CPS) or the PCM doesn't think it recieves a signal from the CPS (bad computer/PCM). and after a few minutes the PCM recognizes the signal and will start. Not always the case will the CE light appear after 5 minutes or so, but most of the time it will.

Remember when replacing the CPS or the PCM to disconnect the battery before removing/replacing either part.

valhalla3 · #5 03-20-2006, 07:27 PM

Thanks for the quick responses!

I was suspicious of the security system from the first day this problem started. During one of the initial crankings the engine sounded like the timing was off, you know like it was fighting against itself. Then the security system came on briefly (horn and lights)

That would make total sense that the PCM is cutting the power....

You were saying there is a purple box somewhere that you can disable or disconnect??? Would this be on a 93 too???

That's 2 for the crankshaft position sensor now. That's definately worth a try. Hey would a scanner report the problem? I might have access to one...

Thanks

Val

valhalla3 · #6 03-20-2006, 07:31 PM

Thanks dksob81 ! Actually I have left the key on for quite some time and the only light that comes on is the security light after a while. The CE light never comes on any more. It did when this problem first started and the engine would start and die instanly once in a while too then, but not now.

I'll try that again tomorrow and see what happens. You say about 5 minutes or longer???

Thanks! - Val

dksob81 · #7 03-20-2006, 07:47 PM

Quote:

Originally Posted by valhalla3

Thanks dksob81 ! Actually I have left the key on for quite some time and the only light that comes on is the security light after a while. The CE light never comes on any more. It did when this problem first started and the engine would start and die instanly once in a while too then, but not now.

I'll try that again tomorrow and see what happens. You say about 5 minutes or longer???

Thanks! - Val

It should come on within 5 minutes, I would say.

Also might want to try to reset the computer, just for the sake of it, you might have some luck. Disconnect the negative battery cable, then turn the ignition key to the START position (with the battery disconnected) and hold for 1 minute, then reconnect the battery and disarm the alarm (unlocking one of the doors or rear ahtch), then see if the CE light comes on when you turn the key.
I don't know if this will do anything but worth a shot.

dksob81 · #8 03-20-2006, 07:54 PM

oo yea also, what you were saying about the timing might be off, this is kinda normal, I get this every once in awhile, like vapor lock in the engine. I think it is due to the starter getting weak and when you try to start it the engine is prolly at it's highest point of compression and the starter barely has enough power to turn it.....lol thats just my theory.

valhalla3 · #9 03-20-2006, 08:15 PM

Thanks for all the advice... I'll try these things tomorrow... Yeah that could be it about the rough start. I've seen a number of things like that happen and it does seem like the starter can't over power the engine....

valhalla3 · #10 03-22-2006, 05:50 PM

dksob81 - You were telling me to try disconnecting the battery and turning the key to the start position and hold for 1 minute. Do you mean turn the key as if trying to crank the engine and hold it on for the minute???. Then turn the key off before reconnecting the battery I assume....

dksob81 · #11 03-22-2006, 06:11 PM

Yes this is right, turn the key as if you were going to start the jeep.

valhalla3 · #12 03-27-2006, 02:10 PM

Hey - Well I tried all those things and nothing worked. When I left the key in the start position for about 15 minutes. I watched it up past 5 minutes but the CE light never came on. At first the ABS light and I think the brake light or something comes on but they both go out and at some point the security light comes on and stays on.

I reset the PCM via bat disconnect and holding the key in the crank position for 1 minute. After reconnecting the bat the headlights and taillights flashed but the horn did not sound like normally with the alarm system. I tried the key in the tail gate on/off but that did not turn off the flashing lights. I tried each door and after doing the front passenger door it went off but I'm not sure if that did it or if it just timed out or something. There was not difference. No CE light and of course it would not start.

So what do you think?

Thanks!

Val

bringselpup · #13 03-28-2006, 04:44 PM

Disco the battery and pull that purple box. Then reconnect the battery and see if that keeps the security system from arming.

valhalla3 · #14 03-28-2006, 05:01 PM

Where is the purple box you are talking about?

Thanks!

Val

ponchonutty · #15 03-28-2006, 05:10 PM

Dude, I just had the same thing happen on a Jeep that came into the shop. The guy was trying to blame my remote start. I noticed that his dash didn't all light up. Tracing things for 2 days led me to the crank pos. sensor. Swapped that out and it started right up.

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