no voltage between ECM and ICM
 

93 civic ex d16z6 120000 miles.

So I have been trying to follow the book and I have found that it says there should be battery voltage between the ECM and the ICMin the dizzy (yellow and blue wire to ground). There is not anywhere near 12 volts. There is on a couple of the other wires. How do I test the ECM? Is it fried or what?

RE: no voltage between ECM and ICM
 

Check the wiring first your problem might be a broken wire. What is the original problem?

RE: no voltage between ECM and ICM
 

The original problem is that I was trying to diagnose a engine knock by pulling a plug wire while it was running. Well, I don't know if it sparked on something and shorted something out or what but all the sudden it died and wouldn't start up. I can hear the fuel pump running when I turn on the key so i'm pretty sure it's getting fuel.

RE: no voltage between ECM and ICM
 

Pulling the plug wire while the engine is running can fry the PCM but I'm not positive that is your problem but its possible if thats what you did.

RE: no voltage between ECM and ICM
 

Is there a PCM or did you mean to type ECM? I'm not getting voltage from the ECM so i'm thinking I need a new one.

Is there a chance that I just shot the main relay? Where is the main relay located so I can test it. Thank you.

RE: no voltage between ECM and ICM
 

Also, if it makes any difference, there isvery little voltage between the tachometer and ICM. The voltage between the ECM is 7 millivolts. With the key off it is 0 volts. I'm wondering if there needs to be 12 volts at the ICM from the ECM or not.

RE: no voltage between ECM and ICM
 

ECM and PCM is the same thing. I tend to use PCM since it is usually what is written in the service manuals. Main relay is located in/near the driver's side kick panel. Below is the procedure for testing the ICM. I haven't really taken a look at the schematic for the ICM so I'm not sure of the voltages.

http://i16.photobucket.com/albums/b5...ess564/ICM.jpg

RE: no voltage between ECM and ICM
 

That's the exact same picture i'm looking at in my book. When I put the tester on the yellow/green wire, I get little to no voltage. When I put the tester on the jack that the wire plugs on to, I get 12 volts. What gives? Why would the wire need 12V if the plug already has 12V?

RE: no voltage between ECM and ICM
 

Blk/Yel is power the ICM. Wht/Blu goes to the coil (primary output). These two should have 12v when key is in the on position. Yel/Grn is a signal from the PCM. You don't need to check the voltage between the Yel/Grn wire, I think that you just need to make sure that it isn't broken. If you have access to a scope, hook up the scope to the Wht/Blu wire and look at the waveform. It should look like a square wave I believe.

RE: no voltage between ECM and ICM
 

The ECU pulses that wire to command the ICM to fire a spark. I would think that if you disconnect the wire and spin the distributor and find someincrease in voltageon the wire, you can conclude the ECU is OK.