Replaced the intake gaskets on my car. Reassembled, time to start her back up and all she'll do is crank, no start, doesn't even try. I've got good pressure at the fuel rail and 12v on the top of the coil with the ignition on.

I plugged in my spark plug tester from the coil to the cap but I don't get a light when I crank... Is that telling me I'm not grounded?

Moved the tester to one of the plug wires, no light there either. Moved the tester to my leaf blower, works fine

 

Is the ignition control module plugged in? You won't get spark or fuel injector pulse without it

 

Yep, the ICM is plugged in. Two plugs, right?

Bad ICM? It started fine before I took it apart.

 

Yea two of them. Check fuses. The ICM could have been damaged if it was hit at all.

 

I was careful to make sure the battery was disconnected while I was working on the car but I'll check the fuses. I took a pic of the position of the dist when I pulled it the first time so I could put it back in the exact position. As far as I can tell, the ICM is the only thing stopping the car from firing.

Where to the two plugs go? They both disappear into a harness between the valve cover and firewall.

 

The two wire harness goes to the coil. The other goes into the main harness. I'm on the mobile app so I can't see the year of your car. Lol

 

91 Z28

305 TPI

 

Just as I described then. Take the ICM off and have it tested at a parts place. Unless u have a few spares like I do. Lol

 

Sounds like a bad ICM. They can work one minute and then at the drop of a hat die on ya. NAPA has some quality pieces for about 30 bucks.

 

I hope it's that simple. Is it worth the extra $10 for the lifetime part? I've heard some horror stories about lifetime warranty on electronics.

 

I got lifetime on my alternator with Napa, 3 years so far

 

I'd just read the fine print, if it means you get a free replacement when it fails again, then I'd say it's worth it.

If nothing else with ICM's it's worth buying two so you can just keep it in the car and not get stranded somewhere.

 

You did put the rotor back in?

Yes...done it before...well, guess "not"done it

Anyways, I don't see the module die-ing from non use, I think you've just missed something.

 

Well...I didn't remove the rotor from the dizzy, so I think I'm good there.

I only get time to work on it during the weekend so I get plenty of time to stew on the problem until Friday.

If I've got power at the top of the coil and pressure at the rail, there are a pretty limited number of things it could be.

 

reconnect power to the coil.

reconnect high tension lead from the coil to the distributor cap

reconnect ECM to the distributor

 

OK. I followed the steps from the diagnostic below and when I got to step 6, I connected the led to the white wire on the coil and it came on steady... It's not supposed to do that right? It goes off when I crank it but doesn't flicker. As soon as I turn off the ignition, the led comes back on steady. WTH?

http://easyautodiagnostics.com/gm/4....ed-icm-tests-5

 

ECM flashes code 12. It's fine.

 

I'm beginning to believe mike is right. I've missed something. What would prevent signal from being sent? Did I forget some other sensor?

No spark, no pulse on the white wire at the coil. Appears to be grounded all the time.
Coil is good.
ICM is good.
Have pressure at the rail.
ECM is code 12.

 

Did you have to take the grounds off the back of the head?..

Anyways, You may as well have the ICM tested, but while you are in there, take alook at the pickup coil, make sure no green corrosions exists..IIRC, it should sit at like 700? ohms, and stay dead solid while wiggling the wires around.

How long did the gasket swap take?

And where was the distributor stored?

Just curious.

 

I don't always do something stupid but when I do...it's really f@(k1n6 stupid. What's worse is now it's on the internet in perpetuity.

Turns out the air temp sensor and the two wire ICM connector are the same style plug. When I put everything back together I got in a hurry and just plugged in the harness that was closest to the ICM...The wrong **&^! one. Flip the plugs, hit the key and it starts.

No shocker here but now I've got a code 23 which is MAT low temp. I likely toasted the sensor in the process.


Thanks to everyone for all of the suggestions! They are what lead me to discover my own dumbassedness.


Be looking for future threads where I ask, "Is that my head or a hole in the ground?"

 

No worries...why do you think I asked you about the rotor?

For sure it wasn't like "I heard about someone...."...

Good news is you have a handle on it!