Hey Guys....I have a 4th Gen but I figured you guys might be able to help me out...

I have a '95 Trans Am and it doesn't start. The dreaded Opti-Spark is brand new. The coil and ignition module work, as well as the ignition switch....

When I turn the car ON, or try to crank the car, no power goes to the coil, however the car still cranks, just won't ignite because there is no spark.

I'm pretty clueless the only thing I can think of is one of the wires from the ignition switch to the coil is broken or something...can you guys lead me to some insight?

The day this problem happened the car was driving, then it would stall, and the clutch would pop the engine back on...sometimes..and sometimes it would coast to a dead stop and I would just crank and eventually it would come back on. Well, now it doesn't even come on...no reading on the meter on the wire that goes into the coil...

Well, I think I covered it all here...

 

LM,

What are the resistances of the coil primary and secondary windings?

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Later,
Vader
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"Let the bodies hit the floor!"
Adobe Acrobat Reader

 

Not sure what you mean....when I put the tester on the wire that goes into the coil is showing no voltage...is that what you're saying?

 

LM,

The voltage to the ignition coil is pulsed DC, and is at about a 40% duty-cycle at 12VDC. In essence, the voltage is turning on and off very rapidly, and is only on 40% of the time, then off 60% of the time, then back on 40%, etc. This should happen four times per engine revolution. An engine cranking at 180 RPM will have a voltage change 12 times per second.

Some meters might not be able to update quickly enough to detect the voltage.

Instead of measuring the voltage, disconnect the primary (low voltage) leads of the coil and measure the resistance. You should read between 0.1 and 1.0 ohms - very low. The resistance of the secondary winding (high voltage terminal) to the negative connection should be 6,000-25,000 ohms (very high). With the wires disconnected, there should be infinite (millions of ohms) resistance to ground on either terminal.

If the coil checks good, you need to move back to the OptiSpark and PCM. I wnet through this a while ago and ended up with a bad trigger wheel and HV switch on the OptiSpark. No fun.

------------------
Later,
Vader
------------------
"Let the bodies hit the floor!"
Adobe Acrobat Reader

 

Hmm...Well I'll be sure to give that a look tomorrow..it's raining now. Uhm, the way I measured it, I measured the '93 the same way so I would have some comparison. The '93 with the key on the "ON" position registered a steady rate of about....hmm I would say 40% of the 15 volt scale, so 7 volts...The '95, looking at the same spot, same wire, with the key on the "ON" position registered nothing, no reading at all.

We also put a screwdriver near the end of the coil and no spark jumped...as well as I pulled the coil wire from the opti and no spark jump, and also i changed the coil wire and no spark jump... Does this help?

 

LM,

If you are checking while cranking you should read some voltage. 5-7VDC sounds about right.

If you have no voltage, you may have a failed amplifier/switch module. It is mounted under the coil on the left head. There is a layer of silicone heat sink grease behind it, and you'll need to clean the surface and replace the white grease if you remove the module. This is functionally the same as the in-distributor HEI module found on older GM ignitions. Failure of this module results in no power to the coil, thus, no spark. The OptiSpark sends its resolution pulses to the PCM, and the PCM operates the module. Your new OptiSpark should be functional. Just make sure the electricla connector is firmly seated in the socket on the upper right (passenger) side of the unit - it's a difficult place to reach and assure a good connection.

------------------
Later,
Vader
------------------
"Let the bodies hit the floor!"
Adobe Acrobat Reader

 

Do you mean the ignition module? That is mounted to the same plate the coil is mounted to. I'm not sure if I mentioned, but I swapped the 93 and 95 coil housings/setups because I knew that one worked....well turns out that both worked. The wires I was testing to see if there was voltage was the negative (black) wire that plugs into the coil. On the 93 (working car) it registerred 7 volts. On the 95 (dead car) it registerred 0. I hope I'm not just repeating myself and going in circles here....I really am posting in all sincerity and I really know nothing about electrical.

 

LM,

Yes, I was talking about the ignition module:



If you've already swapped that and proven it is working, there isn't much left but a shorted ignition coil (causing zero voltage from the module), a defective PCM (not pulsing the module), a blown fuse or fusible link to the ignition, a VATS system that isn't allowing power to the ignition, or a bad OptiSpark unit, including bad connections between any of the above items.

------------------
Later,
Vader
------------------
"Let the bodies hit the floor!"
Adobe Acrobat Reader

 

Does it help for me to add that when the car died on me I smelt some electrical burning as the car was rolling in gear?

 

LM,

Yes, it generally helps to know all the relevant details. There is a 10A fuse in the ignition circuit. An electricla overload in the ignition system may have opened that fuse. There should be 12VDC on the pink wire at the ignition coil at any time the ignition is turned on. If this is not the case, you may have blown the fuse.

------------------
Later,
Vader
------------------
"Let the bodies hit the floor!"
Adobe Acrobat Reader

 

I did check all the fuses and they worked fine..I also swapped them with other fuses in the box that had the same rating (10 amps I believe). Also, I don't think it was the circuit breaker that went because other items listed on the circuit work fine.....

After I smelt the burning, the car did start back up again...maybe not right away...but the burning smell seemed to be when the car was rolling in gear and the ignition didn't start it up. *shrug*

 

Make sure there is a 12VDC supply at the pink wire on the coil.

Waitng for results....

------------------
Later,
Vader
------------------
"Let the bodies hit the floor!"
Adobe Acrobat Reader

 

That would be the pink wire that goes into the top of the coil assembly above the ignition module? Just making sure...I'll be checking that today.

 

LM,

Yes, the pink wire at the coil. Should have 12VDC whenever the ignition is ON.

------------------
Later,
Vader
------------------
"Let the bodies hit the floor!"
Adobe Acrobat Reader

 

Tested the pink wire...0..zilch..nada..nothing. However, the two wires next to it, white and black, test with 7 volts...does that mean anything? They also tested with 7 volts with the ignition off.....

 

LM,

Better take a look at the ignition fuse. You might akso want to look into the wiring from the UEC/fuse panel to the coil,

This might help:



------------------
Later,
Vader
------------------
"Let the bodies hit the floor!"
Adobe Acrobat Reader

 

Looks like I found the problem...the fuseable link in the wiring harness. I'll be replacing that tomorrow...should only be a 10 minute soldering job, right? Hopefully then it'll start right up and I can end my horsepower withdrawal....=D

 

just an update...that didn't work. I think I'm about to throw in the towel on this one! =(