My check engine light stays on constantly, and even after I disconnect the power from the battery the Check engine light is still on when I reconnect the power (with out even cranking the engine over after the power is reconnected, it still comes on). When I retrieve the codes that it should have, the only code I get is code 12. The engine wont fire up, the fuel pump primes and the fan comes on when I turn on the key, which is weird, because the fan shouldn't be coming on when I turn the key to run. Also when I turn the key on, because the check engine light stays on, I don't get the initial quick flash from the check engine light like I used to before when the engine would fire up. Any suggestions would help.!

 

Did it just stop running? What happened when this no start issue started?

 

Yesterday it started the issue when I went to fire it back up after I had disassembled the whole top half of the engine to repair a broken bolt in the cylinder head. The engine cranks, but won't actually fire up. I checked one of the spark plugs and it isn't even wet. So im concerned the computer is bad.

 

So, it ran fine, and you took the top end off and now it won't start?

What bolt was broken and how?

Ground wires reinstalled on rear of head?
Check for smashed, kinked, or cut wires.

Verify all connections are good.

 

Sounds like you may have a short in the fan wiring as wll, grounded out causing the fan to kick on.

 

Check that all of the EFI harness grounds are bolted down. IIRC, there are some that go on the back of the cylinder head(s).

RBob.

 

^ There are RBob, I mentioned that above as well.

 

If you leave the ALDL shorted, the fans will come on. Make sure you have removed your "Paperclip"

 

It was the intake manifold bolt, I had to drill it out and re tap it. I was thinking about those grounds on the cylinder heads, but I don't think the fuel pump would prime if the computer wasn't grounded well enough.

 

oh, yeah the paperclip is removed and it the fans still come on. When the weather gets better I am going to check to see if the injectors are getting power. I'm not sure how I will check the ground from the injectors, because I had read somewhere you are not supposed to ohm the ground through the computer ( I suppose that would screw up the computer). I will definitely remove the grounds on the heads and clean them off (which I should have done from the beginning). I was thinking maybe that is why the check engine light stays on with no codes (besides code 12) is because the lack of grounds.

 

Just curious, is this a conversion ? the fan command maybe the ac fan switch not grounded or open. The mil if this is a conversion the ldm gets chucked.

 

Yes it is a conversion done by the previous owner. I believe that it is from an 88 camaro or firebird. I went outside earlier just to turn the key and now I get that initial fast blink of the check engine light and then it stays on. The only thing about the fans are that the fans didn't come on like that before. So, maybe that problem could be due to a failed coolant temperature sensor. That would make sense for it to be the fail safe mode.

 

Guys! I just remembered that I did replace the ignition control module before I put the distributer back in! So, maybe I got a bad one?

 

IIRC if the ecm goes bad you can have some weird things happen. The ECM controlled fan could very well run with a bad ECM. If you know someone with a good one I would try it before you buy

 

Well it fired up! It was a broken red 12 v ignition wire that goes from the coil to the ignition control module. I decided to check the connections before I removed the coil, and I then found it. So, the ignition module wasn't getting power, and the coil wasn't getting a signal. Since that wire was broken inside the coil, I was concerned about the coil and the possibility of it messing up the new ignition module. So, I then went to the auto parts store and got a new coil, the connection pigtail, plugs, and plug wires. I then found that the number at cylinder wire was broke, so that would explain the poor fuel mileage I was getting. Also the deal with the fan is weird, so that concerns me too. It no longer comes on when I first turn on the key! Everything works as it should now I just hope the computer isn't malfunctioning. Also, I have the 259 dcm ( the supposedly updated gm version).

 

Now the computer is spitting out code 36

 

See, I said it was a damaged wire!

Great to hear your makin progress!0

 

Yeap, Thanks!

Now the fans are acting up. The one fan used to come on when the engine got to a certain temperature, but know it isn't turning on at all. The fans will only come on when I turn on the A/c. They also come on when I turn the key to run with the A/c on. The check engine light keeps coming on and then it goes out by itself.

 

Now its sputtering like it has a serious miss, but then idles normally for a couple seconds then starts running rough again. Now for the coolant temperature switch, when I unplugged it, the fan came on like it should.