Hi all,
I am getting ready to smog my 83 Trans Am next month, but I have a check engine light on, which I'm told by my smog tech that will automatically fail it,

I know about using a paperclip to jump the terminals on the ALDL, however the light will never go into diagnostics mode (Code 12).
Is there a reason why this might happen?
The car runs well and there is no obvious reason why it is throwing a code.

Any tips or ideas on getting ALDL into diagnostic mode so I would be able to check the code(s)?

Thanks

 

There are quite a few possible reasons, starting with, the ECM is not there. (as in, someone removed it) Let's hope it's not quite that drastic.

Some history would help. When was the last time the ALDL worked? Any "repairs", modifications, etc. ever been done to the car? How long has the light been on?

 

Hi, thanks for the reply.
The ALDL has not worked since I first tried to read codes using the paper clip method about 2-3 years ago. However, the CEL has been on since I purchased the car in 2013.
The car is all stock, no modifications to the engine. It is an LG4/T5 car. Recent repairs include a new catalytic converter about a year ago and a driver side exhast manifold gasket about a month ago.

 

OK, so it has never worked, that you know of.

Start simple. Is the ECM present? Is it plugged in?

 

I can say that the ECM is indeed present and is plugged in.

 

Does it have power when the ign sw is ON? (relatively fat pink/blk wire in position C the smaller ECM connector; you can see that wire in your photo but not the pin, it's in the row behind the blk/wht gry & org, look for blk/wht then brn then that one)

ECM fuse in the fusebox good?

 

If the wiring is 'all good' than the problem could be a dead ECM or a problem with the check engine light 'Lamp Driver'.

What is the PN on your ECM ??

 

The battery in my multi-meter was dead so I will have to check if it's getting power tomorrow with a fresh battery. I did however check the fuse and it was good.

I didn't see anything labeled "part number" on the ECM, but it has these two labels on it. Maybe one of them has the part #?

 

You can get a replacement ecm on eBay for relatively cheap.
Just swap in your prom.
https://www.ebay.com/sch/i.html?_fro...3&_nkw=1226025

 

I got the multi-meter working and I am getting 11.83V from the pink/blk wire in position C with the ignition on.

Good to know. I take it the part number for my ECM is 1226025 then?

 

That’s your ecm part number or service number. Your prom should have aka on it.

 

So I tried a used ECM on Ebay and I swapped in my PROM and no dice. Still having the same issue. CEL is on and it doesn't flash when I jump with the paper clip. I started looking into the check engine light 'Lamp Driver' as suggested. Might order one to see if that solves my issue.

 

https://www.thirdgen.org/forums/dfi-...-bad-need.html

https://www.ebay.com/itm/Standard-Mo...UAAOSwR7xcsfdb