Finally getting around to adding this…
One of my original goals with my LS swap was to maintain the OEM Jeep instrument cluster to save the appearance of a stock Jeep.
To do this I ran the Jeep PCM in tandem with the Chevy PCM. I spent some money and time plumbing the 5.3L with Jeep sensors and everything should have work, but it didn't. You see, the gauges are fed (I think it starts in '97) by the signals being multiplexed through a buss going from the PCM to the instrument cluster. Even so, my theory was that the proper sensor would feed the Jeep PCM and send the signal to the dash. This wasn't the case. It appeared that the Jeep PCM was going into a sort of auto-shutdown. Countless hours of research (wire diagrams, web searching, interviews with Mopar techs, and seat of the pants troubleshooting) proved that it is not an auto-shutdown. What happened in my case was, when I would go ‘key-run’ all of the Jeep gauges would light up and read accurately. When I would go ‘key-run/start/run’ the gauges would "freeze" wherever they were and would not move up or down until I went ‘key-off/run’ again. The computer dropped communication with the instrument cluster through the start-run cycle. I had spent countless hours over about six months trying to make this work and I couldn’t. At the time I was pretty bummed, because I tried hard and wanted my dash to look factory.
I decided it was time to give up and go another route. I bought a set of AutoMeter Phantom gauges, and a blue, amber, red and two green led lights from Summit and got started.
Original Jeep cluster minus the pointers and electronics behind.
Gutted the Jeep cluster, and painted black.
Fabbed up the new gauge mounting panel, painted black.