Isuzu Forums - Isuzu Enthusiasts Forum - Electrical Problem on an '01

I'm looking at a 2001 Rodeo 3.2 with a manual transmission. It came into my shop with an intermittent starting problem. It would crank but not fire. When it runs, it seems to run fine, but throws a O2 heater circuit code for all 4 O2 sensors. I don't know if that is in any way related to the no start, but those codes (after clearing) don't return until the car has run for several minutes.

The Rodeo also has a problem losing communication with a scanner. And, with the key on, the fuel pump keeps activating. Every few seconds the fuel pump relay will click on and you can hear fuel pumping into the fuel rail, then it shuts off for a couple seconds before coming back on again. I do have good fuel pressure and no spark or injector pulse while cranking.

When I disconnected the connector at the throttle body (this car is drive by wire, no throttle cable) communication would come back. I tested this multiple times, unplugging it to see communication work, then plugging it back in to see it lost.

I peeled the tape off the wire harness from the TB connector to where it joins a much larger harness on top of the left valve cover. I found nothing wrong with the wires, BUT now I have communication with the scanner even with the TB plugged in (sometimes, it comes and goes). Now when I crank it, it sounds like it I'm getting a spark or two but not enough to get it running. And now it throws codes 1290 and 1295 for the TPS sensors after cranking.

So far I have found nothing wrong with the wires from the two TP sensors to the ECM, but I'm still leaning toward this being a wiring problem and not a throttle body problem, mostly because things seem to change after I move wires around.

If you have read this far, THANKS! Now, has anyone seen this specific problem before? I know wiring problems in this area of the harness are not uncommon on this truck, I just haven't been able to pinpoint the bad wire (if that is what it is).