1994 C4 Optispark question
that was B connector to ground
"measured the B connector on the ICM unconnected nothing I switched to voltage and still read nothing"
Anyway.....
I think you are saying that the ICM connector was off, you put the meter on VAC, then put the red probe on connector B and the black probe on Ground. You do need to have someone turn over the engine while you are watching the meter. You also need to make sure that the VAC range on your meter is greater than 5V. This is not a static measurement like the coil voltage at term. A and D(only need ignition set to on position for the coil Voltage measurement.)
I would also suggest trying the following:
1) disconnect the negative Battery terminal.
2) Disconnect and re-connect the 4 large connectors on your ECM
The above is very easy to do, and this is good practice when you think you may have a open or resistive connection between the male and female pins.
Last edited by MikeC4; Jun 18, 2009 at 09:25 PM.
***NOTE***
MikeC4 has a MAJOR point here. We including me assumed the engine was turning over when you measured pin “B” for the AC voltage measurement. As Mike said,
You do need to have someone turn over the engine while you are watching the meter.
With out doing this you will measure no voltage as it will be the correct reading for that situation. But we need to know what the AC voltage is when the engine is cranking.
Last edited by pcolt94; Jun 19, 2009 at 08:42 AM.
i didnt try disconnecting the battery and pcm i will take another look at the car on Saturday and give you all more results thanks for taking the time on this I will post up some photo of the voltage readings on Saturday or Sunday just so I dont leave anything out
Thannnks again all
Last edited by donkeydawn11; Jun 19, 2009 at 12:33 PM.
i purchased an opti from Advanced and took it along with my old rotor and cap to Dealer and had a Mechanic put it on because I didnt know how far to tighten the screws. I put it back on the car and it still wouldnt start. I took more voltage readings and found no readings from opti unit so I took it off and opened it up and found the rotor broken in small peices. Dont know it it was because the mech tightened the screw to much ?
I went on JEGS and ordered a completly new for $295 I put it in the car still wouldnt start I was living it.
I then by accident touched the b wire on the connector at eht opti and heard the fuel pump turn on. at this point I still didnt have spark at the coil. I then checked I think the b wire it was white going into the ICM while plugged in I took my Bulb tester and put it in the rear of the wire and the car started. I was in haven. even though it cut rught off. In which I believe it was because of the b wire bad connection on the opti. Im going to order new connectors hoping that this will be the end of a long problem
I would like to thank you for your guidence along with the others on this site. You all made this possible giveg me the knowledge to keep trying
Thank you again I will let you know when Im finnally dirving. Ecuse me for any misspelled words in this post but I dont have on my glasses.
A word to all with this type problem as i was taking voltage readings mostly all of them were ok I only found this problem by wiggling a wire at the connector.







