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View Full Version : 98 Auto. Chevy Cav. Problems


stroiber
Jan 8, 2011, 12:27 PM
Hi, my chevy cavalier has a few issues with it currently, The first problem was it wasn't starting and wouldn't idle without dying. You have to put the gas peddle either 3/4 to all the way down to the floor to start it. I've replaced the spark plugs, and the battery, the starter and altenator are both fine. I'm wondering if this issue is related to the second issue within the last week my dash lights will come on when I put the car into drive or reverse (ABS, Battery, Oil, Theft Light.. etc.) Also, when driving down the road these lights also sometimes come on randomly, and also my radio will turn off then back on... I'm thinking it's a computer problem. I had my car scanned and they came across a few errors on there but had nothing definitive to say.. I appreicate any help you may have thank you.

TxGreaseMonkey
Jan 8, 2011, 12:31 PM
I suspect either the alternator or the Ignition Control Module (ICM) is bad. This link should help you diagnose the problem:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-10.html#post1973613

It's always best to begin diagnosing electrical problems by removing and fully charging the battery. Most auto parts stores will do this for free. Then, I would check the regulated battery voltage, while the engine is idling.

If the problem persists, I would replace the ICM. I recommend replacing them every 120,000 miles or 10 years, whichever comes first. ICMs are problematic components. If the battery and alternator are fine, my bet is that the ICM is bad.

Conceptually, the ICM is a large output transistor (switch) controlling current through the primary coil. ICMs replace points and condenser in older vehicles. In the primary coil, current builds to 5 to 12 amps, generating lots of heat (due to inductance). Then, the ECM controls when the ICM "switches off" current to the primary coil, causing amperage to go to zero. When this happens, 12 to 14 volts in the primary coil is "stepped-up" to 30,000 volts in the secondary coil. This process creates a "type" of alternating current required for the coil (step-up transformer) to work. In a properly working ICM, timing is precisely when needed to fire each spark plug.

Bottom Line: ICMs and coils take a beating.

stroiber
Jan 8, 2011, 01:01 PM
Where is that located on the 98 cavalier? Any links to diagrams..

TxGreaseMonkey
Jan 8, 2011, 01:15 PM
The coil packs plug into the ICM. Go to AutoZone.com and enter your car's data.