I just bought a car last weekend it is a 96 TA. Owner said he drove home and went to leave another 15 minutes later and it wouldn't start. This was supposedly 4 weeks ago.

I towed it home and bought a new battery, old one wouldn't hold a charge. Now it cranks over great but I am getting no spark at all not even a weak one. I followed the testing from shbox.com and the voltage on the ICM read 12VDC on both A and D terminals. However it only read a constant 0.1VAC when cranking at the B terminal and I never saw a fluctuation to trigger a spark.

Are there any other things I should check before I replace the optispark? Wiring appears to be fine.

Lastly does the crank sensor at the bottom have anything to do with the ignition system in the car or what is it's purpose?

Thanks to the shoebox for the great website!

-Taylor

 

A bad coil or coil wire would result in no spark.

 

Do it the old fashioned way. Check spark at the wires, if no spark check it at the coil. Most cases its going to be a either a bad coil or worst case scenerio bad opti. IF that doesnt work then start looking at your icm.

 

I would replace the coil and ICM, before changing the opti. More than likely if you are not getting any spark out of the coil, It is not going to be an opti problem. The optical sensors rarely go bad, it is the cap and rotor that goes bad. So many people have changed opti's to find out, the opti was still good.

So you bought a car that did not run?

 

That's what I was thinking also. However, according to the shoebox's website. The test I did above is looking for the opti's pulse when the engine is cranking and it was not seeing any pulse. I will check continuity on the coil to see if it is good just to be sure.

 

If the computer never sends a signal to the ICM, the coil is not going to fire. No sense in changing the coil and ICM if the signal is never getting there. Check your opti connections, too.

 

Exactly my thinking. Thanks for the conformation. I checked continuity from all the plugs at the opti and ICM back to the PCM and everything was fine I procedeed to removed the opti and when I got the waterpump off I saw that the plug at the opti was broken and it didn't even seen like it was plugged in hardly.

Can anyone tell me which place the dowel from the cam should fit it? I mean which hole? I would think it would be the one labeled 2 in my pic. Maybe it doesn't matter at all?

opti.jpg

 

Also does anyone have the opti pigtail connector GM part number? I'm gonna need to get one...

 

anyone?

 

Yep, it's 2.

GM 1995-1997 optispark (vented)
electrical harness p/n 12130319 .

Less expensive harness used by many

 

Many many thanks! You are the man!

 

Well I swapped the opti and still nothing. Well let me specify what I am seeing. When I swapped the opti for another opti that I know works I did the test at the ICM connector and I am seeing .1-.3 volts AC not 1-3 volts but tenths of a volt. I am assuming that is not enough voltage to fire the coil correct?

I'm guessing that this leads me to a bad PCM? Is it 100% positive that the Crank position sensor has nothing to do with firing? It was unplugged when I got the car...

Thanks!

 

shoebox are you there? I need your expert advise before I buy anything else.

Thanks in advance.

 

If you had someone that you could swap a computer with, that would be helpful. Obviously, I can't tell you exactly what your problem is.

 

I understand. I was mostly wanting to know if seeing tenths of a volt is definatly a problem or if that should trigger the coil.

Thanks.