I have a 97 Z28 that I converted to OBDI. I believe the PCM is out of a 94 Caprice or Roadmaster. I had Mo do a mail order tune to get the car started, and it starts and seems to run well once it idles out. Mechanically it starts and idles well, but I'm having a few issues with electrical functionality and would like input if you think it's PCM swap related or otherwise.

1. Gas gauge is pegged past full with less than 3 gallons in the tank. I replaced the gas tank and upgraded the fuel pump and wiring to the Racetronix kit.

2. Air bag light always on.

3. Ebrake does not seem to be registering as up when it is pulled and because of that, the lights are always on. Not sure if they'd still be on in the sunlight, but in the garage, they are always on. Thinking this may just be an adjustment or replacement of the parking brake switch.

4. The keyless entry doesn't work even with a new battery. Bad remote or is this related to swapping pcm?

The ebrake isn't a huge deal, but the air bag light and gas gauge are because it will see its share of street miles.

The car has been sitting for 7 years so it may be bad sensors or cracked wires or something, but before I start pulling stuff apart (especially the gas tank) I was hoping someone with experience could shed some light on it for me.

 

All of your symptoms definitely sound like it could be PCM related except for the E-brake. Did the car have any of these problems before you did the PCM swap?

 

No it didn't. I stopped driving the car in ~2007 and have basically stripped it down and rebuilt it over the last year and a half including the swap from OBDII to I.

 

I was gonna say none of the things are PCM related.

Gas gauge does not go through PCM.

Air bag has its own computer.

E brake does not go through PCM.

Keyless has a BCM that runs it.

Now, that does not mean that some of your stripping and rebuilding did not cause the problems.

 

Yeeeeeeeaaaahhhhh, that's very likely. This was my first big build and for these to be the only things wrong so far, I'm pretty proud of myself. I learned a lot and have a lot left to learn. That said, the fuel gauge is probably a bad sender or broken wire and the e brake is probably a bad or misadjusted e brake switch.

Any idea what could be causing the air bag light to be on? That's a big concern to me.
How about the keyless entry? Tried to pair it to the car per the manual and no dice.

 

Are you sure? A good friend of mine has a 96 z28 and when he switched from OBD-II to OBD-I, he had a lot of similar problems to the op.

 

There are lot of people that switch back and forth from OBD-I to II by merely swapping the PCMs and without an issue. I'm going from memory , but no wiring diagrams I have seen lead me to believe this has anything to do with the PCM. What wiring diagrams are you looking at that lead you to this conclusion?

 

Why convert from OBDII to I?

 

I swapped from OBD2 to 1 because tuning the OBD2 PCM requires more money than I'm willing to spend. I ripped the PCM out of a 95 Fleetwood at a junkyard, plugged it in, swapped my knock sensor, and bought an ALDL -> USB cable on eBay. For about $100 I now have a car I can tune and datalog on the fly with my laptop thanks to Tunerpro and a Winflash trial. Probably the best mod I've done to the car.

I've had no issues whatsoever.