Code 51 issue in 3.0
 

I just bought an 89 pickup with the 3.0 It has 156K on it and the previous owner had just replaced the timing belt. I keep getting codes 51 and 52. The timing marks underneath the cover are all lined up and after adjusting the timing with the distributor slightly its at 10*BTDC. Ive tried resetting the ecm by disconnecting the battery and removing the fuse for the ecm but I still have code 51 without even turning the truck on after attempting a reset. Im going to try what some other threads mention about the replacing the knock sensor (no power, bad gas mileage, hesitation) but Im curious to know why I would still have the code 51 after resetting the ecm? Ive read that its for the TPS but I get a code 41 when I unplug it. Could 51 mean something different in the 3.0? COuld the fact that it doesnt clear from the computer at all be an indication of something?

Inspect for shorts in the diag port, and between the diag port and ecm. After you find out why it's going into diag mode all the time, you need to figure out which other part is triggering the code 51 TPS, tranny indicator, or A/C switch, could also be someone adjusted your idle with the cable instead of the Idle adj' screw. But again, first you need to find out why it is going into diag mode.

Im sorry; I should have clarified. The truck doesnt constantly flash as though its in diagnostics mode, but after I attempt to clear the codes by disconnecting the battery/removing the fuse; it still shows the code when I jump the two ports to read codes. I was under the impression that there shouldnt be any, at least not until I cause a condition to create the code.

No a/c and its a manual transmission. So Im guessing the next thing you would tell me is to check the cable and idle adjust screw? :)

Cable should have a little bit of slack to it, and check the TPS adjustment if it's good at the Throttle-body check at the ECM.

will do thanks.