First off, Jeep won't start. Here's the WEIRD part, took the coil wire off the dist cap and wedged it between two other wires so that I could see if there's spark while cranking since fuel is good and getting to the rail. No spark, but then when I turned the key to the OFF position my dad said he saw a spark. Did it a couple times and it would only give a spark when I turned the key off. What could that be?? Couple co-workers said to pull the ignition control module and bring it in to get tested. Any other ideas? Thanks

 

If you are getting a single spark when you turn the key off and at no other time, the CPS is probably shot.
The coil's magnetic field collapses when the key is turned off. That's your one spark.

 

Perform a voltage test on your CPS first.



Renix CPS Testing and Adjusting
　
　
Renix CPSs have to put out a strong enough signal to the ECU so that it will provide spark.
Most tests for the CPS suggest checking it for an ohms value. This is unreliable and can cause some wasted time and aggravation in your diagnosis of a no-start issue as the CPS will test good when in fact it is bad.
The problem with the ohms test is you can have the correct amount of resistance through the CPS but it isn’t generating enough voltage to trigger the ECU to provide spark.
Unplug the harness connector from the CPS. Using your voltmeter set on AC volts and probing both wires in the connector going to the CPS, crank the engine over. It won’t start with the CPS disconnected.
You should get a reading of .5 AC volts.
If you are down in the .35 AC volts range or lower on your meter reading, you can have intermittent crank/no-start conditions from your Renix Jeep. Some NEW CPSs (from the big box parts stores) have registered only .2 AC volts while reading the proper resistance!! That’s a definite no-start condition. Best to buy your CPS from Napa or the dealer.
Sometimes on a manual transmission equipped Renix Jeep there is an accumulation of debris on the tip of the CPS. It’s worn off clutch material and since the CPS is a magnet, the metal sticks to the tip of the CPS causing a reduced voltage signal. You MAY get by with cleaning the tip of the CPS off.
A little trick for increasing the output of your CPS is to drill out it’s mounting holes with the first drill bit that just won’t fit through the original holes. Then, when mounting it, hold the CPS down as close to the flywheel as you can while tightening the bolts.
　
Revised 11-29-2011

 

Either the CKP is kaput and not generating a signal, or the coil feed circuit in the ICM is shorted through.

To generate a spark, the low-voltage side of the coil is fed an electrical current. This generates a magnetic field in the windings and core.

When this primary current is broken (points open or the circuit is broken electronically,) this magnetic field collapses, inducing a current in the secondary (high voltage) side of the coil. (An ignition coil is little more than a transformer, and works in much the same way. It just functions on "pulsed direct current" instead of alternating current.)

This current is what generates your spark.

If the CKP is not generating a timing signal, the ICM won't know to cut current to the coil and allow the spark to form

If the ICM coil feed circuit is shorted through, it won't open - and the magnetic field won't collapse and induce the secondary current (until you turn the key off, interrupting the primary coil current flow manually.)

Which is more likely? Don't know! Test by elimination: if you have a good CKP signal being generated, your ICM is probably hooped. If the CKP doesn't generate a signal, replace it and retest (the CKP is usually responsible for generating a base timing signal for both the ignition and fuel delivery subsystems.)

In fact, another useful test would be to take a "noid light" (standard little dingus, should cost you less than ten bucks) and plug it into one of the fuel injector connectors - this will tell you if the fuel injector pulses are being generated and delivered (if you lost both ignition and fuel injection signals, the CKP is the likely culprit.) Just in case, check about half of your injectors.

 

Hey thanks for the feedback everyone. I had just replaced the CPS before I posted this so I'm hoping I don't have a defective here. I thought for sure after I replaced it, it would start. But no, noticed the single spark turning the key off instead so I decided to post this. Just pulled my ICM and coil out and I'm gonna bring it in to work tomorrow to test.

 

OEM or other? This is one of those things where you really should bite the bullet and pay for the OEM. I've had nothing but trouble with flaky/intermittent/heat sensitive china bombs from Autozone. Got 3 bad ones in a row for a Saturn before learning my lesson. (Definition of: "The hard way")

 

I had it sitten here so I pushed the button on my kitchen timer, went out, opened the hood, checked the CPS, came in. < three minutes! (it had .3 ACV, failed a few months later).

From Cruiser;


Renix Jeep ICU/Coil contact refreshing
　
　
The contacts between the coil and the ICU on your Renix Jeep can become corroded and loose causing a complete or intermittent no-start condition. I recommend the following procedure as a maintenance precaution to insure this is eliminated as a possible cause now and in the future.
The coil is attached to the ICU by two T20 Torx bolts. Remove these two bolts and lift the coil up off the ICU. You will see 2 pins and 2 sets of contacts. Clean both the pins and springy contact pieces with a good electronics cleaner.
Squeeze the springy contacts closer together with some needlenose pliers. Apply some dielectric grease to the contacts and bolt the coil back on to the ICU.
While you’re right there unplug the connectors from the ICU and inspect the pins in the harness connector. Make sure the pins are not retracted into the connector. Spray out the connector and the receptacle of the ICU with the same good electronics cleaner you used earlier. Apply dielectric grease to the connectors and plug them back in.
I feel this procedure should be performed at least once in the lifetime of a Renix Jeep.
　
Revised 11-29-2011