11-11-05 Updated with ALDL cable links OK, finally got the time/inclination to do something for those that don't have service manuals, or those that do and just don't want to scan this stuff in, or want to read it at work, etc. As you will see, Trickster over on thirdgen.org has been nice enough to scan all of these charts in. Be forewarned, these are F-body diagrams, so you TBI/CCC folks should be careful, but you will find most things are identical I'm sure. Not complete of course, but at least everything I could find is now in one post. I will update as I find more. PM me (if you can) and have more charts to add, that way the thread doesn't get bogged down with responses unnecessarily. Chevythunder code/troubleshooting list I can't vouch for those. Not factory scans, but look to be the same info in a slightly different format. 1990 R/V truck wiring diagrams ALDL pinout ALDL cable scematics Ignition system test This is for TPI, but should be pretty close to TBI as well. Some of the tests I guarantee are. Identifying TPI system differences Vehicle repair guides Check these out for wiring diagrams, etc. Can't vouch for how good the quality is, but I see that our trucks are listed. TBI O2 Open circuit Codes 15/23/32 CTS coolant temp low/MAT sensor low temp/EGR Code 24 VSS Code 42 EST Code 43 EST TPI MAF wiring diagram MAP interior harness connector pinout Codes 15/45 coolant temp/O2 sensor 2.8L port Code 23 Inlet Air Temp (IAT) low temp indicated Code 24 VSS Code 32 EGR Codes 33/36 MAF gm/sec high and MAF burnoff Code 34 MAF gm/sec low Code 41 Cylinder Select Error Code 42 EST Code 44 O2 lean Code 54 Fuel pump circuit low voltage CCC Code 23 M/C Solenoid volts low to ECM Code 24 VSS Code 32 Baro sensor Injection specific: crank no run 1 crank no run 2 External coil, pickup testing MAP voltage/baro/vacuum chart C100 (fuse panel) connector '85/89 Camaro I also have the entire GM TBI/TPI troubleshooting sections, '89 Camaro, in .pdf (about 2MB each) if someone is interested in hosting those somewhere that I can point people to, PM if so. The TBI Camaro stuff is identical to truck in almost every regard.