my friend has a 94 bonneville ssei supercharged. we need help.i don't know gm electronics, i'm a dodge guy but a car is a car when iit all boils down to it...anyway


his car runs ok, no knocks or pings, good power etc but it throwing about 9 codes. it does a little hesitating once in a while which i'm sure is due to the ecu going ape sh*t.
he had a mechanic tell him to start by changing the ecu.

my questions????????
1. how do you clear codes on a 94 bonny? i know on a dodge you just pop the negative cable and pull the fuel pump fuse. is it that easy on a gm car or do you need to erase it with a special electronic tool?

2. when changing the ecu is it plug n play or does it need to be flashed to the car'* VIN?

please help if any1 can? we need to ge tthis fixed on saturday morning

Do you have the correct scantool to read the codes? If so, get them, then erase them, if they come back, and have no effect on the car, replace the PCM. The 94/95 H-Body GMs have a awkward PCM that has a high tendency to fail, and it is probably on it'* way out.

he already had it scanned. i know what the problems/codes are. it'* very 'failed pcm' related in my opinion along with the mechanic that did it.
how do you dump the codes? does it need to be hooked up to a scan tool to do that or can you just kill the power like on a chysler and reset it?.
he has a new ecu reay to go in so can i just swap it out or does it need to be flashed?

No flashing necessary. The PCM needs to be from a 94/95 ONLY. The Eprom (chip) must be from the IDENTICAL car. That would be engine, supercharger or not, and trans gear ratio.

Dumping the codes would require disconnecting the battery for about 10 minutes or so. Give it 30 for good measure.

94/95 PCM'* are known to be a bit 'flaky' at times.

To reset codes you can unhook the battery for about 20-30 minutes.

When you get another pcm, remove the two small screws that appear to hold on the access panel. Swap your eprom chip to the new pcm and try it out. The usual failures are the hardware of the pcm and not the eprom chips.

1 more quick question??
the pcm, is it located under the dash in the car or under the hood?. the reason i ask is because my buddy says it'* under the dash. again, i'm not too familiar with gm products.
i did do an engine swap (3800) on a pontiac transport van (FUN! ...ya right! what a pain!)
and the haynes manual i have shows it'* pcm under the dash aswell, pass side.

thanx for the help so far guys! we really appreciate it, good group here!

Under the dash on the passenger side. IIRC it'* laying on the firewall.

were in windsor are you ? I have a spare unit around if you need to try it out

my buddy is coming from lansing mi and has already bought a brand new 1 state side for cheap. thanx for the offer though. so i just pull it out, swap the eprom chip (i'll do it according to the same instructions as the transport van manual. it'* explained in there) and hopefully that clears up these issues!. is it a bitch to get at being up against the firewall or is it fairly accessable? it'* gonna be cold out tomorrow lol

pretty easy to get to just take down the hush panel under the dash and at the far rite aganst the fire wall you will see red white and blue plugs that is it it just kinda slides out of its holder there