Here you will find general information about the 1998 to 2002 F-Body LS1 wiring harnesses. A few things to keep in mind. The 1998 harness used a different PCM. Lay out may be the same, but the PCM pinouts were entirely different. Must use 1998 Harness with a 1998 PCM. (Note that 1997 LS1 Corvette uses same PCM as 1998) 1999-2002 wiring schematics and pinouts should be very similar, if not the same.
1998 LS1 F-Body Harness Connector Pinouts - Note that 1998 had 3 connectors under the dash C210, C220, C230
1998 LS1 F-Body PCM Connector Pinouts - shows which wires can be removed, which to keep for external connection
Below is a before and after picture of a LS1 Automatic wiring harness I recently modified. This is what you would get if you sent your LS1 F-Body wiring harness to me to be reworked. Click picture to see a high resolution image.
Here is a tip when eliminating oxygen sensors. If you plan to run headers, you will need your oxygen sensor wires more rearward then stock harness has them. The FRONT and REAR sensors are the same plug, so, what you can do, is REMOVE the FRONT connectors, and then MOVE the pins for the REAR Sensor back into the location for the FRONTS at the PCM. You now have enough wire to reach any location for the oxygen sensors. You will remove the Tan & Purple for Bank 1 Sensor 1 completely. Then MOVE the Tan & Purple for Bank 1 Sensor 2, into the location you just removed B1S1's pins. Do the same for Bank 2. The picture of the wiring harness above on the right shows this done in finished form.
The modified LS1 harness has the rear oxygen sensors re-pinned for the front sensors, the front O2's connectors were removed. You can also leave these in stock location, if using stock manifolds. I also move the Crank Sensor (CKP) to allow the harness to stretch out more, and allow PCM placement under the dash. Near the PCM is the Diagnostic Port, Check Engine Light, and some other wiring needed to complete the install.
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