I installed a '95 Pontiac 3800 V6 in my coupe. Prior to this effort, if it didn't have a carburetor and a distributor I didn't have a clue as to what made it run. I still have a whole lot to learn but my recent purchase of a PC based scan tool is sure gonna help that process.
After researching the available tools I found there were basically two kinds, ones that just read error codes, (read 'cheap') and ones that perform many more functions (read 'not cheap').
Went ahead and ordered the "Ease" scan tool. $315. PC based. Ordered it with the OBD1 (On Board Diagnostics, gen 1) connector. GM cars mfgr'd from '82 through '95 use OBD1. '96 on use OBDII. Big difference, but OBD1 is much friendlier to the the rodder. As I suspected, it only needed 2 of the 12 pins on the connect or. "A" - ground, and "M", serial data for engine diagnostics. Other pins are for things like the restraint system, or the ABS brakes. This is my first experience with any scan tool and I really like it. Software install was straight forward, hookup was simple and worked the first time. Called tech support just to clear up a coupla questions. Great service, talked for about 1/2 hour, no bums rush.
I have had the engine running several times prior to getting the scan tool and one of the problems was a VERY high idle for a while, then it would settle down. Never knew what that was about till now. Tool showed a DTC (Diagnostic Trouble Code) 123 (TPS (Throttle Positioning Sensor) sensor high voltage).
Found that the reason for the high idle was I had hooked up the 'A' and "C" pins on the T PS backwards (+5V and Ground). But that is exactely what the manual indicated! Result? The PCM (Powertrain Control Module) thought WOT was idle and idle was WOT.
I have a main battery switch which I always turn off whenever I am done working on it. What I did not realize, is that I was reseting all DTC's when I did that. Then, next session, main battery switch on, start it up, goes a little nuts with the high voltage reading and idles at 2500 till the DTC is set at which time the PCM forces a more normal idle.
Anyway, I thought some members might like to 'see the Ease scan tool in use' so I captured several screens and other related photos depicting the process I went through to solve the problem and downloaded it all to a Yahoo album. Be sure and scroll down (if you have to) to read the 'name' and 'description' fields as that is where I 'tell the story'.
I find it interesting that that error (in the shop manual) survived but then no one working on a stock Pontiac would have a reason to ever be aware of it.
Click on the link below...