Ignition module?

[korny351]

I've been getting the CEL off and on for some time now. Code reads 224. Primary coil circuit failure. Did find a bad coil and replaced it. CEL still pops up intermittently. Symptoms include low idle (<500 rpm) and tach will sometimes read approximately 1/2 value. These symptoms will normally coincide. No major loss of power since the coil replacement. Just the intermittent low idle and erratic tach. AIC has been cleaned and checks out and the TPS has been replaced. I'm leaning towards a bad ICM. Any input will be greatly appreciated.

I removed the ICM to have it tested at Autozone and noticed a white paste on the base where it attaches to the manifold. Reminds me of heatsink paste on a CPU. When reinstalling the ICM should this be removed for a better ground or should it be reapplied and with what product?

 

[dgeorge]

It is the exact same thing as heat sink compound and should be reapplied when reinstalling the ICM. It helps to transfer the heat build up from the ICM to the intake manifold to keep the ICM module cooler. Hope this helps.

 

[korny351]

Well. the verdict is in. ICM is bad. Time to hunt down a replacement. Hoping to find one less than the $150 that Autozone wants. Any suggestions?

 

[fastpakr]

Call your local junkyards. See if they'll sell you a module with a warranty of some sort (all you need is a few days). I bought one for $40 and went straight to the parts store to have it tested. Once it tested good I was in the clear. In my mind, it's better to go through a couple of used ones for half the price of a single new one. The truck will run on a partially failed module, so keep your current one around. It would be different if you were dead in the water with a failed one. This is a little less critical. My junkyard unit has about three months on it so far with no problems whatsoever. For what it's worth, if you swap in an instrument cluster with a tach you will probably see the module failure on the tach. Half rate RPM display is pretty much an instant condemnation of the module.

 

[korny351]

Thank for the suggestion, Fastpkr. Haven't been to the local Pick & Pull in awhile. Last time I was there my '93 was newer than anything on the lot. Hopefully, they'll have some newer stock to pick from.

 

[locovaca]

According to Rock Auto a 90-97 Ranger or 91-93 Mustang ICM will interchange. If you don't find one, it's "only" $90 for one on Rock Auto- looks to be a refurb, though.