This information is based on my findings, specific to pre 2004 GM trucks, VPW J1850 protocol, with a pin out of 2, 4, 5, 9, 14, & 16. The PCM and BCM are the 2 modules providing the 7V supply for network functionality, and testing for network integrity cannot be done, as there are no terminating resistors within the network. The following pinout is relative to options and what is on, at least one, ‘99 Chevy Silverado LS 1500 5.3L
| Pin Number |
Pin Name |
Description |
|---|---|---|
| 1 | Not used | |
| 2 | J1850 | |
| 3 | Not used | |
| 4 | Ground | |
| 5 | Ground | |
| 6 | Not used | |
| 7 | Not used | |
| 8 | Not used | |
| 9 | SIR 01 | |
| 10 | Not used | |
| 11 | Not used | |
| 12 | Not used | |
| 13 | Not used | |
| 14 | Cell Coms | |
| 15 | Not used | |
| 16 | 12V Bat+ |
Information for Identifying the wires in pins 9 & 14 is found on the wiring diagrams. Options specific to your truck may be different, and therefore, your pinout may vary.
correct
incorrect