sweet, first thread again

[The DanSmith]

Well, this one is quite confusing actually....... My Mom's 1996 Grand Am is throwing a CEL, but when we plug in the scanner, it says the codes cannot be read.......ad this is on the NYVIP inspection machines. What's the deal

PS: Thanks for the forum LWillmann!

[Tailwind]

could be computer interface problem, bad computer, short in a wire, and others. Thats one of those I need a probe and an Ocilliscope issues, unless you happen to have an extra computer laying around for it..You could try unplugging the battery and it helps if you leave a light burning while you do it so all caps and memories are discharged and erased. Other than the basic engine control functions. Leave unplugged for a while and then turn off what ever light you left on in previous step. When reconnecting the battery terminal watch for any arc. If an arc is present, there is an issue with a bad relay transistor that turns certain functions on and off or a short of some nature. It could be anywhere if a scanner wont communicate with the computer. But id tend to say blindly of course, that the interface wiring to the outlet for the scanner is in some way to blame. Has anyone installed any audio equipment or altered any thing that happens to coincide with the problem you noted?? If it still runs properly the comuter innards are okay. Check wiring that runs to oxygen sensors under the car to see if they have been caught on something. Man there are some many things with these computers that can be wrong. A diode can die and cause hair pulling adventures. Id love to help more but Im in Georgia. Allthough resetting the computer by removing all power and let it reset itself if its not bad. at least that may allow you to communicate with scanners and get a code. then you know more where to look.

My car started missing on one cylynder so I take the 5200 dollar Snap On scanner , hook er up and it says cylynder #6 not firing. Duhhhh like I didnt allready know that. Ended up that one post on a coil was dead. It has 2 coils that fire 4 opposing cylynders, better recovery time etc. I always thought if the coil died all the cylynders connected to it would die. Not the case with computers running things. Well good luck and post your findings. I am as curious as you as I havent run up on that particular issue before.