Hello All,
Fairly new to the forum, although I’ve been lurking in the background.
. I have a 2019 GMC At4, 5.3L (L84 engine)that has been overtaken by gremlins lately. I already changed the water pump (65k dealer screwed me on extended warranty ).. For the most part it hasn’t been too bad. But I recently hit 100,000 kms and everything suddenly started to fall apart. Last fall it was A/C, garage claims it’s the clutch; but recently I asked if they did an ohm test and there’s no record (you’ll understand where I’m going with this in a sec). Then, mid winter, after returning from our vacation, the dashboard lit up with a myriad of codes, that weren’t even related; main one was accelerator speed sensor low voltage. Brought it the garage to diagnose, because I’m 20yrs old anymore and no longer a driveway warrior 
. They found salt build up in the harness and bypassed the original connection (accel sensor) and ran a new wire.. Problem solved, no more limp mode. Two weeks after that, I get another check engine light, low oil pressure. Gauge was fluctuating, then suddenly a few days later gauge went to zero.. While researching which wires are which, to confirm voltage at the pigtail (which I did 4.7v) i read that the oil pressure sensor, accelerator sensor AND the A/C clutch all share the same voltage; so now I’m wondering if all these are connected and the issue lies with this harness. I changed the sensor yesterday, because it would’ve cost as much to get the garage to bench test it and it ran fine until about 15-20km later (dropped to zero again). It seems like the pressure is there, initially, but after a 10 min drive it completely falls. I haven’t done a manual reading yet (kit should be delivered tomorrow) but has anyone experienced similar issues? Do you think it’s all related? I’m contemplating swapping harnesses, but it’s approximately $1,000.. Or removing it and going through it myself, repairing all the wires, if any at all; but that would leave me with no wheels for a few days. 
Any insights would be much appreciated
Fairly new to the forum, although I’ve been lurking in the background.
. I have a 2019 GMC At4, 5.3L (L84 engine)that has been overtaken by gremlins lately. I already changed the water pump (65k dealer screwed me on extended warranty ).. For the most part it hasn’t been too bad. But I recently hit 100,000 kms and everything suddenly started to fall apart. Last fall it was A/C, garage claims it’s the clutch; but recently I asked if they did an ohm test and there’s no record (you’ll understand where I’m going with this in a sec). Then, mid winter, after returning from our vacation, the dashboard lit up with a myriad of codes, that weren’t even related; main one was accelerator speed sensor low voltage. Brought it the garage to diagnose, because I’m 20yrs old anymore and no longer a driveway warrior . They found salt build up in the harness and bypassed the original connection (accel sensor) and ran a new wire.. Problem solved, no more limp mode. Two weeks after that, I get another check engine light, low oil pressure. Gauge was fluctuating, then suddenly a few days later gauge went to zero.. While researching which wires are which, to confirm voltage at the pigtail (which I did 4.7v) i read that the oil pressure sensor, accelerator sensor AND the A/C clutch all share the same voltage; so now I’m wondering if all these are connected and the issue lies with this harness. I changed the sensor yesterday, because it would’ve cost as much to get the garage to bench test it and it ran fine until about 15-20km later (dropped to zero again). It seems like the pressure is there, initially, but after a 10 min drive it completely falls. I haven’t done a manual reading yet (kit should be delivered tomorrow) but has anyone experienced similar issues? Do you think it’s all related? I’m contemplating swapping harnesses, but it’s approximately $1,000.. Or removing it and going through it myself, repairing all the wires, if any at all; but that would leave me with no wheels for a few days. Any insights would be much appreciated
Something to look into. They just performed the recall for the negative chassis cable just prior to.. u may be onto something too
