Car runs great, when it runs...possible security system prob

[hobbie2k]

It's a '93 SSEi.

I just fixed a bad running issue with the car yesterday (bad spark plug wires). The car ran great all day.

This morning (very cold) my wife went to start the car and it wouldn't fire. It cranks fine, but won't fire at all. About an hour later I went down to try and it immediately fired up for me and settled down to a nice idle. I took it for a short drive to recharge the battery. It was running perfectly fine. On my way back home the car engine just stopped.

There was no power loss, no stumbling, no indication at all of a problem, it just stopped. I coasted to a park and the car wouldn't restart. It cranks fine, but won't fire.

My first thought is the security system may be malfunctioning. Sometimes when I'm driving the security light will stay on and the car will occasionally make the "bong" sound for no apparent reason.

Can the security system cause this sort of problem, where the car cranks but won't start, and can it kill the engine while driving? Thanks.

btw - I've done some searching and am going to try and see if disabling the RAC will help. Is there a fuse for it or do I just need to find the module?

[MattStrike]

It sounds like a problem with the VATS. The normal operation of the security light is to stay on for a 5 second bulb test when you turn the key, then turn off and never come back on while the vehicle is running.

The key has a resistor pellet that the VATS module uses to verify the correct key is being used in the ignition. If the contacts in the ignition are dirty it might not be reading it properly, or they might be bent and have intermittant contact with the key pellet. This is a somewhat common issue and if cleaning it doesn't work or fixing the contacts in the ignition cylinder doesn't work and you can't get a replacement cylinder... there is a bypass: measure the resistance of the key pellet and get a resistor to match the value, then bypass the ignition cylinder contacts by hardwiring the resister in. If that doesnt work, there is a schematic floating around to build a 555 timer circuit that replaces the module entirely.
Either option I recommend having a hidden kill switch to maintain some sort of security system, as bypassing these functions defeats the VATS. I've wired them up to work with an aftermarket security system as well.

[hobbie2k]

I was looking at that as a possibility, but in other VATS threads I've got the impression that it won't crank at all if VATS isn't functioning properly.

[crash93ssei]

VATS won't kill the engine while it is running, and also like you read in another thread, the engine won't even crank with a VATS issue.

Sounds to me like the ground buss. On both the drivers and passengers side if you pull the carpet up just a bit by the front doors you will see a wire harness. There is a bunch of black ground wires that go into a single connector, the ground buss. These are fairly common to corrode and cause issues with the fuel pump, windows, interior lighting, and any other electric powered options.

[crash93ssei]

Check this thread out for pics of the location of the ground buss - viewtopic.php?f=19&t=30286

[hobbie2k]

That's an idea, because the windshield surround does leak a little so the driver's floor is often moist...

[hobbie2k]

The shop thinks it's a bad crank angle sensor, but they can't get the pulley off to replace it. They're saying something about a blocked puller bolt hole...

[crash93ssei]

Ignore the shop and go after the ground buss. That is free to check out yourself, if it is fine then take it to the shop.

[hobbie2k]

The crank angle sensor is fine. Fortunately the shop isn't charging me for the time they spent working on that. They put a new ICM in and it works fine now. But they want $220 for the part. I'm wondering how hard it is to replace the ICM myself if I can find a cheaper one?

[crash93ssei]

ICM is super easy to replace, 6 5.5mm screws hold the coils on it and one bolt through the electrical harness connector.

I still say it will be worth while to look into the ground buss. This is a very common problem for the '92 - '99 Bonneville, and I have experienced it myself with my old '93 SSEi as well as my sisters '93 SSE.

[hobbie2k]

I am definitely going to check out the bus, even if it's not causing this specific problem. Thanks for the help.

[crash93ssei]

No problem. Also for the ICM, make sure you use new dielectric grease on the bottom of it.

[hobbie2k]

So I picked up a used ICM off a running '97 SSE (parts numbers were the same on Rock Auto). As it happens, the car was running when I picked it up from the shop, so I drove it home, and put the used ICM in.

The car wouldn't start.

So I put the original ICM back in and the car fired right up. I drove it around all day and it ran great. I was hoping it just turned out to be a bad connection. This was about a week ago. I went back out to start it today and it won't start again with either ICM.

I didn't know about the dielectric grease till I saw your response today, could that be causing this issue? I was actually thinking before of using some on the coil connectors to try and improve the connection...

Also I just noticed that someone stole my front license plate sometime this week...

[crash93ssei]

Have you checked out the ground buss yet?

The grease wouldn't cause a run, no run, run issue. It would run until the ICM overheated (unlikely this time of year) then be totally fried and never run again on that ICM or only run on two or four cylinders.

[hobbie2k]

yeah, i checked the ground buss and it's fine. Shiny, no corrosion, hooked solidly together...

...maybe I fried the ICM when I installed it without grease...

[crash93ssei]

I highly doubt it. Not saying it isn't possible, but I doubt it.

I had a similar issue with my old '93 SSEi and it took me about two months to track down my issue. I had three known good ICMs (one only fired four cylinders / two coil packs, but I used it for testing purposes) it would randomly run or not run on each of the three ICMs at any given time. My issue took me so long to find as it was a shorted out wire on the back side of the engine, it was a pink / black wire that was factory spliced in about three or four different spots to deliver power to multiple sensors, including the oil pressure sensor and the ICM. What happened with mine is a clamp that was supposed to hold the wire loom to the back of the engine had slipped down the loom and wore through the insulation on that wire just enough to short it out, yet it didn't pop the fuse right away.

I tried replacing the crank sensor as I thought for sure that was it, then the cam sensor, then went after the PCM, then the ICM, then found the shorted wire finally after the fuse finally started blowing.

Not saying this is your issue, but it could be something similar. There are a couple fuses on the passenger side of the dash, right above the kick panel under the dash. Remove that panel and check to make sure all the fuses are good.

[crash93ssei]

Check this thread out, this is from back when my '93 SSEi died on me randomly and then continued to have start / no start issues with four different ICMs.

There is a lot of useful information in there that very well could help you find your problem.

viewtopic.php?f=19&t=2371

[willwren]

Dielectric grease won't 'fry' anything. VATS won't allow the car to even crank. There are two ground busses. Did you check them on both sides of the car?

[hobbie2k]

I looked up that thread, Crash, and there is a lot of good stuff in there.

I've checked both ground busses, both are clean and tight. I've checked all the fuses, including #6 and all the ones under the hood and in the passenger footwell and all are good. I felt up the wires running back along the ICM and didn't feel anything odd, but I can't start pulling things apart because I'm in an apartment parking lot, and just having your hood up can get you in trouble...

There does seem to be a little corrosion on the ICM mount, which I intend to clean up, but I need to buy a wire brush, and some dielectric grease and I am completely broke right now. What's the best way to get it good and clean?

I would hope that the shop had tested current to the ICM and found it fine, but I don't have a voltmeter so I can't confirm it myself...

Thanks for the ideas and suggestions, guys. But I'm beginning to think I should just cut my losses and scrap the car. Too bad because it's pretty much rust-free (rare in this area) and ran great before this.

[hobbie2k]

I hope I'm not jinxing myself here, but I got the Bonneville started today.

I basically pulled the ICM, backing plate, and bracket out of the engine. Cleaned them all real good, getting off all the corrosion, dirt and grease. Then (after letting them dry) put some di-electric grease in between the bracket and backing plate, the backing plate and ICM, and on the coil terminals. Put it all back together (cleaning off and putting grease on the three ground wires and any part that touches the block), jumped the battery, and she fired right up.

I took it around the block a couple times, then let it idle for about half an hour and it ran fine. So, after the engine cools again, I'm going to try and start it up again (this isn't the first time it seemed fixed). If it starts and runs good for a while then I'll call it fixed.

I'm guessing that when the spark plug cables were replaced, either some dirt fell in between the ICM and backing plate, or maybe the parts were shifted just enough to cause a loss of ground and that's why it wasn't working...

Thanks again for your help.