Good afternoon,

Car: 98 A4 1.8T manual

I am trying to test resistance for my ICM and found the following post while searching, for a Passat 1.8T:

"Testing the 4D0905351:
1) Remove the two connectors from each side of the module. This is done by pressing down on the wire spring clip and pulling on the plug. They should come out easily.
2) Borrow or buy a handheld Digital Multimeter (DMM). They are available from Radio Shack or off eBay. The cheaper ones can be purchased for around $25-$30. It's a great investment!
3) Set the DMM for resistance measurement. Most DMM's today have auto-ranging so you need not select a range. If yours has a range selection choose the highest resistance range.
4) Connect the DMM's + (Red) lead to the middle pin on the modules five (5) pin jack. It is important that you connect the + lead of the DMM. These modules are made up of four power transistors which are polarity sensitive. Even though you are making resistance measurements the DMM does apply low voltage DC to the circuit.
5) One at a time connect the – (Black) lead of the DMM to each of the four pins on the four pin jack side of the module. Each pin should give a resistance reading of around 2.5M ohms (2.5 million ohms). Provide yourself a tolerance and say that 2.0M to 3.0 M ohms is OK. If any pins gives a complete OPEN or a resistance value other than that in our range that sparkplug/coil driver is bad. If you show all of them OPEN maybe you have the DMM connected backwards. It seems like on the module the four pin jack has cylinder 1 as the pin closest to the letter B in Bosch. From there it just counts up by cylinders 2, 3 and 4. This is just a guess and I didn't officially check it out. However, my car gave the error code P0302 which is the ever famous cylinder 2 code. Sure enough on my module the second pin down from the letter B in Bosch gave me infinity ohms (OPEN) on my DMM. The remaining three pins read between 2.3M and 2.6M ohms each."




I Tested my own and got .925K ohms accross the board. Can someone PLEASE give me what the correct resistance should be? Or can someone please confirm the 2.5M ohms from the posting to be correct?

Thank you very much!

 

Also, can anyone give me any additional tests I could do on the module?

 

Anyone? :-(
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You can't test resistance of the ICM or power output stage and get a good result out of it. What you need to do is use an LED while cranking the engine with a special pin out box which you don't have. If you have a miss-fire on a pre-00 1.8T engine then just change the ICM, thats all there is to it.

 

Mine is actually not a misfire, but no spark at all (any cylinder). I've already changed the crank sensor and nothing, so the ICM was my next step.

 

The ICM doesn't initiate spark to the cylinders the ECM does, the ICM just steps up this voltage (thats why its called the power output stage)
So if you already replaced the crank sensor then you either have a bad ECM or wiring/blown fuse issue.

 

I would try checking all the fuses that you can find, im assuming you have no faults either?

 

I've checked all the fuses in the driver's side panel. Are there any more fuse boxes on this car? There are no codes either. That is another thing, if the ECM was bad, shouldn't the scanner have issues connecting to it? I bought an Actron scanner and I am able to see live sensor data while cranking.

 

It depends on what is wrong with the ECM, most times you can still communicate with it if it doesn't have a data bus failure.
Its different from model to model but there is fuses next to the ECM itself on most A4's, and the main relays are under the steering wheel. So you have no spark on any cylinders while cranking correct?

 

That is correct, no spark on any cylinder. Is there any way you could post a photo of the next-to-ecu fuses? By the way, your help is very much appreciated:-)