Ikester

Our 1991 Trans Am Convertible (Yes-Convertible) (305 V-8)died backing out yesterday and the Service Engine Soon Light came on. It won't restart. My Haynes manual talks about codes that will tell me what is wrong, but not really where the computer is. I have dismounted a computer from under the dash on the passenger side. One website says to put a wire in port C11 and C12. I don't want to go inserting a jumper wire without knowing for sure it is correct. I don't want to blow something else. Please let me know exactly where the test panel is and how to make it display codes. Thank you Thank you Thank you

G.Penrod

The jumper should go in the upper right two pins in your OBDI port. In my Camaro it's above your right chin area while seated in the car. Your Service Engine Soon light will start blinking. It will blink a 12 code three times first then proceed to display your other codes three times each after that. When it's done with all the codes it'll blink the 12 code again.

Ikester

Not sure where the OBDI port could be at "Chin Level" when seated?

G.Penrod

My bad, spelling got me. I meant shin.

G.Penrod

Your key needs to be in the 'Run' position but not running.

Drew

iTrader: (58)

The ALDL on 91 Firebirds is by the fuse block.

Ikester

OK, Found the ALDL under the dash, drivers side, next to the fuse block. Installed the jumper and the only thing that flashed was the 12 code over and over and over. So that makes me think no problem there. So I need air, fuel and spark for the engine to run. I know we have air (I think) not sure about spark or fuel. I kinda think maybe fuel pump? I grew up working on Chevy 283's etc, so computerized cars are not my most knowledgeable area.

sofakingdom

iTrader: (1)

What you have is the same as a Chevy 283 except with a disadvantaged bore/stroke configuration.

Shoot some starting fluid or gasoline into the intake. If it runs, you have a fuel delivery problem. If not, a spark problem. Same as a 283.

Ikester

I was finally able to check for a code on the Service Engine Soon light. The engine had been cranking slow. The battery was six years old, so I got a new one. Cranks rapidly now. The only "code" showing is 12 over and over again. Since that revealed nothing I took the advice. Need air, fuel and spark. Knew I had air. Checked spark and there isn't any. Check all the fuses I could see and they are OK. SO I am thinking coil or distributor. Is there a way to check them, or just replace parts until it runs?

OrangeBird

iTrader: (1)

Good , now you know you have no spark . The very next test should be to see if with the key on there is 12 Volts on the pink wire going to the coil . An "automotive test light" will do here if you don't have a meter , and of course having 12 Volts will likely mean the coil , ICM , or pickup coil has failed
, whereas no 12 volts will send you back to the ignition switch to see if it has 12 Volts , and so on .

PS , before it even gets mentioned , the factory installed VATS (Vehicle Anti Theft System) does not affect spark in any way , it kills the injectors and cranking of the engine only , so is not your problem here ...

henryd3

iTrader: (128)

You might try taking the Ignition module out of the distributor and taking it to an auto parts store that will check it for free. Call and ask. Have them check it several times in a row if they will to heat it up some. Then begin diagnostics. If you don't have any kind of workshop manual you should consider getting one. You can throw new parts at it and maybe get lucky before you spend a fortune needlessly, or systematically figure it out

Ikester

I have a Haynes manual, but it some areas it is a little vague for this car. I checked for 12v power at the pink wire and it checked good. So I went to NAPA and got a new coil. Still won't start. Can I safely pull the wire from to coil to the distributor (from the the distributor) and check for spark? How do I remove the ignition module? I did see some rust in the distributor when I looked in there.

henryd3

iTrader: (128)

with the cap off, remove the connector on the back of the module and unscrew the two tiny screws that hold it on . Careful, don't drop the screws. Reinstall is the opposite but coat the bottom with either the delectric stuff that comes with a new module if you get one, or better yet they sell tiny tubes of heat sink compound at Radio Shack if they still exist that works better. Get some if you can and hang on to it

sofakingdom

iTrader: (1)

If you can't get it at Radio Shack, try a Micro Center or Fry's.

Ikester

Called the local O'Reilly's and they said they could, indeed, check the Ignition Module. So I took it in and it failed the test. Bought a new one, installed it , and HOORAY! Started right up. I fell into the trap that it was computer related. Went back to old school with your advice and solved the problem. Thanks Y'all! Thank You Thank You Thank You.

henryd3

iTrader: (128)

Cool, glad it worked out.