Hi Guys,

I have a 1987 northstar fiero. Engine is from a 2002 cadillac deville, 4.6L DOHC. It has the donor PCM in it but the dianostic plug is not from a 2002 deville nor is it the stock fiero plug.... I am not sure how I am suppose to check the engine codes? My service engine soon light went off today and I have no idea how to check the codes. Like I said, the dianostic plug is not from a 2002 deville nor is it from a fiero (or at least it does not match my stock 1986 fiero and the haynes book does not show two different plug styles). This plug only has three terminals. The bottom terminal is a ground (I tested it with a multimeter). The top too are connected to each other because when I put them together (via the multimeter), I get a completed circuit.

Pic is below. Someone please help.



Thank you,

The 2002 PCM is an OBD2 computer so you can't just jumper some pins and have it flash the SES light like on the OBD1 (Fiero) ECM. You need a specialized OBD2 code reader. The codes in an OBD2 system are alpha-numeric, like P0303 for instance, so it's not something that can be displayed with a simple flashing light. The connector the reader plugs into on the car doesn't look like the one you've shown in your picture either. It's bigger and has more pins.

you need the 16pin OBD2 coonnector, i dont recognize that one. Cant tell you how to wire it without a CM pinout though.

So if I can not read these codes as is. What do i need to do so that I can? Do i need to get a dianostic plug out of a 02 deville? If so, how do i wire it to the pcm so it can be read? I understand I can not flash it. I have to have a reader or have autozone, ect read it.

What computer are you running the 2002 Northstar with?

It looks like a Fiero ALDL to me. Just quite a bit out of focus.



So who did the wiring on your engine swap?

Go to a junk yard and pull the ODBII connector from a post 95 car. Saturns have a fairly easy to pull ODBII connector. The one on a caddy is going to be a pita to remove.

Pins 2, 4,5 and 16 need to be connected for your scanner to work.



I don't have a pinout of your PCM handy to tell you what pin of your PCM that pin 2 of the ODBII connector connects to however.

I have no idea who wired the car, i bought the car completed. I was told it has the 02 deville computer. I'll check to make sure, today if i have time. Which model of saturn vehicle should I pull it from.

96 - about 2002 SL. Or any small car 96+. One that has a screwed on OBDII connector. It should look like this:

I'd give a good look at the wire harness under the decklid to see if it isn't dangling there. I rather doubt the PO would've gone through the trouble to remove it especially since it's needed to diagnose problems anyways. He may have taped it up out of the way.

Amy other ideas where it could be? A few questions / comments I asked in the video.

It's not critical that the ECM be hard mounted to the firewall, though the vibrations over time from it rattling around could affect it. If I were you, I'd find a way to mount it. As for other ideas where the diagnostic link might be, check behind the seats, and perhaps under the dash for it. I can check my '97 harness that I have in a box a little later this evening and guide you regarding which wire bundle to follow from the ECM to find it. GM probably didn't alter the harnesses much between '97 and '04 so it might help.

That would be great if you can check your harness later tonight, thank you. I also noticed something (see below)



I meant obd1 connector (the fiero connector thats currently there).

[This message has been edited by 1986FieroGT (edited 06-29-2011).]

Are you sure your engine is an '04? There is a popular OBD1 computer that is used to run '99 and earlier Northstars, and that's what your ECM looks like. The last four digits of the OBD1 ECM's part number are 7730. A stock Caddy OBD2 PCM has cooling fins on it. Do you have a part number on the computer you're running? How many pin holes are there on the two ECM connectors (it's hard to tell from your video)? Here's what the difference is between a stock Fiero ECM (top) which is similar in appearance to a 7730, and a Caddy PCM (right) forget about the one on the left. Notice how long the electrical connectors are on the Caddy PCM vs the Fiero ECM? What does your's look like?

Thank you so much for your help. I really love the pennock community. I was told the engine was from a 2002 cadillac deville (however I have found I was lied to about a few other things so that info may not be correct).

The ecm looks nothing like any of the three you have pictured. There is a sticker on the ecm that says:

16200896 BKFX
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | (BAR CODE)
*86BKFXM533563053

It looks like this:

http://howellefi.com/norths...994-95-cadillac.html

Obviously I was misinformed (lied to) about this car. According to the year of the pcm I have in the car; the motor is from a 94-95 deville concours. However this means the pcm is using obd1.

[This message has been edited by 1986FieroGT (edited 06-29-2011).]

Do you have a picture of your engine?

Yes, they are below (attached to this post). The engine matches what the 94-95 deville concours comes with (4.6L 32valve northstar and looks the same). However I was told it was from a '02 deville. My PCM is obviously from a 94-95 concours so it is very likely the engine is too.





Does anyone know how I can check my codes now since we have discovered I have an obd1 computer? I tried to paperclip the two terminals and I turned the ignition into the first slot (the same way I do the other fiero) but the SES light does not flash.

Judging from your throttle body, it looks like a 1996-1999 to me like mine. its not a 1994 because your cover is not part of the intake manifold. If your computer looks like the Howell unit (three colored exterior connectors: red, blue and white) then its a 94-95 PCM with a service number: 16197429 or 16196402. That is the recommended computer by Howell, though your supposed to change the throttle body to the 1995 unit. But, yours is not a 95. Its a 96 and later.

So, it looks like who ever did your conversion used a 1996-99 engine running it with an OBD 1 computer using the Fiero ALDL port. You should be able to take a cheap 80's era scanner and plug it in the ALDL port and read it.

[This message has been edited by IXSLR8 (edited 06-30-2011).]

Yes, obviously a '99 or older engine with the DIS and plug wires. The '02 and later engines used coil packs that bolted to the cam covers.

Get rid of that cover, neaten the wiring and show the engine off

Here are pictures of a '00 and newer Northstar: https://www.fiero.nl/forum/A...090907-2-060639.html

So now what I need to know (or find) is a pinout of a 94-95 deville concours ecm so that I know which wires go to the dianostic plug. The current wiring on the dianostic plug does not work. It has two orange wires going to it and one black ground. I have jumped all of them in all possible combonations and it does not flash any codes at me (not even 12 so I know it is not in dianostic mode). Maybe the guy didn't wire the plug correctly, I left my haynes deville manual in my dads car so I wont be able to check that for a few hours. If anyone knows or has stubled across the pinout of that computer; please update me with it.

[This message has been edited by 1986FieroGT (edited 06-30-2011).]

You should be able to find the pinnout here: http://v8mr2.com/reference.asp