contraststriker

iTrader: (14)

a little exposition:

so I have ABS INOP and AIR BAG warning lights on. I took it to a reputable repair shop and they couldn't even get their scanner to communicate with my car, let alone get error codes. So I called the Pontiac dealership and some guy said "oh, well that repair shop probably just had a generic scanner, we have ones specially designed for GM vehicles." Riiiight, I know that this place has a GM scanner, geez--what mechanic wouldn't have a scanner for one of the three main auto manufacturers in the United States...So I jumped on carputing.com, bought the cable for my car, and loaded up a PCM communicator program onto my PC. I hooked it up to my car and got a single line of text, something to the effect of:

interp: bad chksum error bad chksum F44...(and about fifty more weird letter-number combinations)

from what I understand, isn't this a pretty bad error? Don't all PCM configurations have to add up to a certain total, and mine isn't apparently? Is this why the damn thing won't even communicate with a scanner? What do I do?

Yeah apprarently dealerships aren't allowed to pull technicians away from jobs to answer questions so I can't ask them. Wow dealerships are GAY.

AAron

the check sum have to do with the vin.

contraststriker

iTrader: (14)

a little more explanation? Come on guys don't make me go to the dealership and lose half my summer's income fixing the PCM...

Snow Dog

iTrader: (3)

why not just get a new ECU? they arent expensive for OBD1. and yes the dealership does have a specific scanner that will be able to enter that ECU even if its fried. its called Tech 2. its not cheap and most places do not have one. do you realize how many people call a dealership looking for free adivce? do you understand how much time would be wasted if techs spent time on the phone with people answering questions like that? not every problem a simple single answer.

now how about some more info like whats the car doing? just the two lights? did you check the connections?

outdooricon

Well, I can add my two bits about chksum... At elast what it means in the Computer Science World. A checksum is basically a summation of all of the bits in a file (In your case I would assume it to be the 'PCM' file). So the only thing I can say is that something was written wrong to it (by somebody who didn't know what they were doing, like a bad flash) and so the shcecksum doesn't mathc what the file should be. That's what it would mean in the Computer Science world.. it may be entirely different in the auto world.

AAron

i believe that is where they get the check sum digit in the Vin.

and yeah i did some checking and the PCM might be fried.

contraststriker

iTrader: (14)

UPDATE:

I fixed the ABS and AIRBAG lights, turns out the ground wasn't quite grounded. I'm a dumbass, thank you.

But this still leaves me with the checksum error. I haven't hooked my PC up to the car again, but abs and airbag stuff wouldn't cause a checksum error would they? I mean, I should get the checksum error again when I hook it up, I think.

OBD I PCMs are $200 new from GM...ouch. Thank you all very much for your replies thus far!!!

contraststriker

iTrader: (14)

nevermind, only the airbag light is fixed. Now the ABS INOP turns on about 10 seconds after starting the car. *sigh

dhdenney

iTrader: (53)

Well if the PCM is fried then it wouldn't run, correct? Does it run normal? No missing or backfires? The ABS light will come on for a variety of reasons and you aren't going to get a code because the ABS is run through its own computer, which I think is under the dash on the driver's side. One of your front hub sensors could be out or the sensor on the top of the rear end could be bad. I believe a third brake light out will throw the ABS INOP light as well but I don't think a tail light will.

EDIT: I thought a little more about it and I think if you unplug the third brake light from the harness it will throw the light not a bulb out.

zcarguy

Which program are you using to read the PCM?
Some programs require a config file so they know what the PCM setup should be, if your program requires one and you have the wrong one it will report all kinds of errors that are not real.
I know TunerCat is this way.
Check this before doing anything else, and as stated above if the PCM was fried the car would not run at all.
No the ABS INOP error should not cause a checksum on scanning the PCM.
Your cable might also be bad or the wires to the ALDL connector might be bad, check these as well before buying a new PCM.

ZcarGuy