If my ECU is ok, then what else could it be? The resistance in the coil meets the specs so I think the coil is good. I read another thread where the guy did the exact same things as me by pulling a plug wire while running and it died. Long story short, he replaced the coil and it fired right up. Thing is, I don't want to spend $60 on a coil that I cannot return.

 

check main relay

 

I bought a coil for 60 at auto zone and they took it back for me.

 

I cranked the engine with a socket wrench on the crankshaft pulley and the voltage at the yellow/green wire stays a constant 7.2 mV. With the key off, it's 0.

 

It may have to turn faster than that. I'd suggest disengagning the distributor from the cam so you can just spin the rotor (make sure to keep distributor grounded though) or using the starter. Actually try it both ways with the yellow/green wire disconnected from ICM and with it connected as it may need current from the ICM to pull up the voltage.

My bet is (1) ICM or (2)coil, with the ECU as a remote possibility. If you don't have spare parts handy you can borrow you may havetodo"shotgun"replacement but that is rather expensive.

 

The service manual says that I should be getting battery voltage at the wire with the key on. The coil tests OK but i'm still not sure on that. Have you ever seen a coil test out OK, but replacing it fixed the problem?

I have not been able to locate the main relay. I've looked really hard to find it near the left side of the drivers side kick pannel. I can find nothing that is held on with screws excpet over by the gas pedal. It has 3 screws but doesn't look to be the main relay. Could it be under the hood?

 

Main relay is tough to reach, it is pretty much directlyabove the hood release handle. I don't think it's your problem here as it primarily controls the fuel pump and injectors. You have the 12V to the coil and ICM regardless of whether the main relay is pulled in or not.

If you do try disengagning the dizzy and spin it with the key on several things will happen, the main realy will pull in, the fuel pump will start, and the ICM should drive pulses to the coil. If you're in a quiet place you may hear clicking or thumping from the coil. In that case the coil is definitely the problem. It is possible for a coil to get an internal short and check out OK but not generate any sparks.

Also if you spin the dizzy fast enough the tach on the dash should go up; that signal passes thru the ICM so you'd definitely have drive from the ECU then but the ICM could still be bad.

 

Does it make any difference if I have no voltage TO the tach? (blue wire)

 

When testing the yellow/green wire, it goes up to around 50 mV with the engine cranking from the starter. Does that indicate that I have a good ECM?

 

Is there a way I can put a jumper wire in something so it will tell me if the ECM is even regestering? That would be great help to me at this point.