i replaced both ignition coils and the tach still does not work. i have and 84 gsl. i read something about a wire connecting to one of the coils for the tach signal. i noticed i only have a positive and negative on both coils but no other wire is connected to it

 

Are you getting fire to both trailing plugs?

 

i am not sure...how would i be able to check this out?.

 

Remove one of your trailing spark plug wires from the spark plug. (its labeled on the side of the motor) If you have a extra spark plug place it in the end of the trailing wire that you removed and attempt to start the car. You should see spark in the end of the plug.

 

im not sure if this has anything to do with the problem but while i was tryin to find out the problem (this was prior to posting this thread) i tried to make sure all the plugs were plugged while the car was on. i touched one of the spark plug wires goin to the ignition coils and got electrocuted. i touched the insilator also and was suprised that i did get electrocuted. wonderin if this makes any differences..

 

The signal to the tach is from the trailing ignitor (I think). With that much voltage coming from the coils yes it is very easy to get ''electrocuted''. You might want to check your whole ignition system at this point. This means check your distributor cap and rotor, wiring, spark plugs, coils and igniters. Do you have the Haynes manual?

 

It is likely due to a bad trailing igniter. Do like the others have said and check to see that you are getting spark from the trailing coil. If you are then it is probably either a wiring problem or that the tach itself is bad.

 

Yes the trailing ignitor sends the signal to the tach, I just went through this on my car. I agree with locklei, test the spark on one of the traling plug wires by plugging in a spare. Then just get someone to turn it over a few times and you'll see a spark or not. Make sure to ground the plug end on the car.

If the trailing ignitor is gone, both traling plugs will not be firing. The trailing plugs are the top two, and labelled with T1 & T2 on the cap.

 

Trailing igniter. If you want to prove this to yourself, switch the two igniters. The car won't start because the bad igniter is now on the leading plugs. If the leading plugs don't fire, the engine won't run.

 

I'm having spark probs with my car now. I change the igniters and the trailing , that I put on was back. I didn't check the spark to find out. When I started the car, the tach wasn't working. Put the old/good trailing igniter back on, bam, worked again.

so replace that igniter.