Hi there everyone. I have a no start thread going. However, I thought I'd devote this one to this topic so that it is easy to find for future searches.

I have been told that o'reilly's can test the ICM. I called my local one and they said that they don't have the wires to connect it. I went to another local one and they saw that they could test the ICM but couldn't find the part number to reference which harness to use. I went to a 3rd one that the guys didn't know up from down so I struck out today.

For those of you whom have had o'reilly's test one in the past, is there a specific part number that you referenced to allow them to find the right harness? When I tell them 1992 corvette lt1, they keep telling me that they don't have it/can't test it.

Anyone have any other suggestions? Pep boys, autozone can't test them at all apparently. I'm located in Southern California.

thanks!

 

If they are not smart enough to use the phone either you could do it for them. Sadly some do not have a clue but many do.

 

I just had my ICM tested today at AutoZone. It's for my '86, so obviously doesn't apply directly to you. This thing has left me stranded several times but they couldn't find anything wrong with it. They did the test several times at my request but it passed every time.

 

I called the 4th o'reillys and the guy said they can so I tossed my parts in the car. We'll see if they really can!

 

If you actually are successful you might inquire the branding of the equipment and maybe the harness # if it's available. I believe it's maybe important to note the temperature of the ICM if you get the "GREEN LIGHT". An ICM that tests good I understand gets HOT, "GREEN LIGHT" and cold might generally be determined to be a "FASLE" positive. Branding of testing equipment might dictate the likelihood of that.

I believe that the testing equipment likely depends upon the "date" the store was opened and then upon the maintenance of the equipment by personnel.

A "newer" store might likely not have the older technologies and harness adapters for similar equipment. The chain likely buys packages for testing of what's considered "popular" in the market-place. The adapter/harness for the LT remote ICM might likely not even be available from the manufacturer any more.

 

A lot of times testing the ICM in a store can give misleading results. They usually malfunction due to high temperatures under the hood. Hard to replicate that in an air conditioned parts store with a kid just trying to make some pocket money.

 

are you sure t he problem isnt the optispark?

are you using a cheap knock off or a genuine oem optispark?

(come on qwiketz i think highly of you and doubt that you are using a cheap chinese unit or msd optispark)

 

Hi guys. I finally found one that could test it:

2801 s Bristol in Santa Ana

I brought in 2 and the guy said the machine didn't see any resistance which told him that they were bad.

Does this sound about right? I understand one that tests okay may give a false positive, but bad is bad right?

About the opti.. Correct I installed a dynaspark which was one of the better options.

 

Just replaced mine on a 93, Vette died on me. Did set a code 42. Followed the steps in the FSM, changed it out. Did the coil while I was in there, started right up and runs great.
Got the ICM from Rock Auto under $100 bucks AC Delco.
Got the heat sink grease at Radio Shack.

 

If you want, I can post the diagnostic from the FSM.

 

Thanks for the offer. I have a fsm on DVDs but I just have to get to using it! Hopefully this weekend.

 

 

so I took them to another store today to be run and they both failed again. Time for a new icm.

 

What is an ICM? It is no more than an amplifier. It takes the 5 volt square wave pulse (AC voltage) from the ECM/PCM and makes it large enough for the coil to use and be driven. The output of the ICM is approximately 70 volts p-p (somewhat of a square wave) into the coil.

When testing this item, a proper input and output is required for a valid test. I have no idea what the auto parts stores are doing or how it's being tested. It's a solid state amplifier and I don’t know what a resistance measurement would tell you other than it's dead shorted. And their test will probably not address a heat increase in the unit and if it keeps working.

Substitution is really the best way to determine if it is defective or not which is the reason I have a spare. By having a spare cuts down the troubleshooting time with an high confidence factor of where you are and which way to go.

You don’t even have to mount it just to see if the engine starts. Just swap over the plugs and make the "test". But don’t run the engine for any length of time as it will get hot very quickly (less than 10 seconds).

 

It's a little more than that. It also amplifies and squares up the signal from the pickup coil before feeding that signal to the ECM. There is also a basic advance curve built in that takes over if the ECM loses control of the spark advance.

 

The INNOVA ICM tester patent pretty much explains the what an ICM is and their tester does.

Their tester patent:

http://www.google.com/patents/US5635841

I expect this or very similar is used in most auto chains. Advance Auto I believe uses this tester (read it on the Internet soo...). An AZ employee on the phone told me he didn't know the brand but if you called an AZ and asked if they had the "NR" adapter they could check the LT1/4 ICM. I don't know first hand.

INNOVA seems to have newer testing that actually does/can do a print out.

If some one visits one of the "auto chains" it might be worth the asking in advance of suspecting needing one.

Post back if they'll share the branding maybe.

 

To be more exact we both are right however I should have more specific that I was talking about the engines that use the opti 92-96. I believe your describing the earlier C4s that are using a distributor like the years of car you may have. Different ignition configuration.

There is no pick up coil with the opti (obviously), drive comes from the ECM/PCM.

I try to keep it simple with the basics so most will understand the concept.

 

<br >Here's a picture of the machine they used. The machine has many different uses depending on how you hook it up . There is a multiple page on his chart that the tech looks up the application and therefore knows what harness to use.

There is a multiple page on his chart that the tech looks up the application and therefore knows what harness to use.

 

Good to have passed that on!

That appears to be a "re-branded" from a vendor that uses the INNOVA 4400 as the device and then repackages/decals etc. for distribution:

http://www.coil.innova.com/Product/Detail/4400

 

Good to have passed that on. It looks like maybe a newer or older "rebranded" version maybe of the INNOVA. The charts used are likely custom for the "auto parts chain" - they look up their part# and it uses that as a reference for the harness/connector. Their website "hints that" and the INNOVA does similar but with select "manufacturers" rather than chains. (SMP, Wells etc).