Sigh, my saga continues...

Current Problem: Engine cranks but does not run

In an effort to figure out what the heck is wrong with my Bonneville, I got a copy of the Factory service manual. Using the electricial diagnosis, I narrowed it down to being something to do with the electrical system.

Possibilites include the Crankshaft Position Sensor being faulty, the ICM being dead/not handing over to the PCM, Ignition coils...

So, seeing as I've got the tools handy, and this wonderful website has the resistance values for the coil packs, I yank the coils and check them....

3/6 - Secondary - Overflow/No circuit Primary - 0.2Ohms
2/5 - Secondary - Overflow/No circuit Primary - 0.2Ohms
1/4 - Secondary - Overflow/No circuit Primary - 0.2Ohms

As you can see, this isn't correct.....

Either I'm doing something wrong (doubt it) when measuring the coils, or all 3 coils died at the same time...what the heck could cause that? An overload in the system somehow? What could cause a big enough overload in the ignition circuit to fry all the coils?

Next step I guess is to go to the wreckers and find some of the same coils and measure them. Also, I'm gonna clean the ground plate and the ICM, they are filthy...

Thanks in advance for any advice.

Hmm.....secondaries all indicate open? That'* crazy I have to admit. Coil secondary resistance should be up there approx. 5-8 k ohms

Please do me a favor...check the battery in your mulitmeter. Mine gives poor readings along those lines when the battery is low.

If that isn't the issue...that'* very odd.

I would think if you get absolutely nothing ...it'* probably the crank sensor or the wriing harness to the sensor.

Being that you have the FSM.. using your multimeter follow the steps to test the wiring, coils, ICm and crank sensor to the best of the manuals information. This should point you in one direction.

I don't want to insult you, but I don't know your skill level with the multimeter. Could you perhaps have the setting on the meter too low to read the higher resistance of the secondaries? Having all 3 go at the same time is strange.

If the meter setting was too low..I'd still expect to see a 5 or 6 at the beginning..not a 2... it'* odd.

Uh..heyyyyy did you remove the coils to test them or were they still on the ICM? I'd noticed different readings both ways..I think.

It'* an autoranging multimeter.

Bill,


I tested the secondaries both on the ICM and pulled. Open circuit each way.

Primaries, you can only test by pulling, and all of them read 0.2ohms.

The fact that the engine cranks but doesn't run was leading me in the direction of the crank sensor, since according to the manual, the only signal required to start the motor is the CKP Sync signal. If the crank sensor is dead that would also explain the behaviour, but why would the coils go...

Thats the million dollar question. Why indeed. I doubt we've ever seen all three at one time before.

Well guess I'm off to the wreckers this weekend to find some coils and test them...

If I'm reading correctly what he posted, he put that the secondary read overflow, and the primaries read 0.2 ohms. If he'* using a low resistance setting, which is like to be able to get to the tenths of an ohm, trying to read resistances in the thousands of ohms without changing that setting will show open, or overflow.

Dick..the meter is autoranging. ... his readings should be right. That'* where my checking the battery in the meter comes in...I've seen odd stuff on a low battery.