BruceW

I do not see an L92 specific location in the Electrical Manual. Does anyone know where it is located? Also does anyone know where and what the SA550 ground is? I am trying to fix a weak ground to the RUN / CRANK fuse. SA550 is notated in this diagram. Not sure what it is. Thanks for your advice.

It was a $70 starter off of Amazon and I believe the 225K mile starter was bad. Early on in my troubleshooting the positive lead that powers the truck, not the one that powers the starter was pulling 60 amps when the key was turned. Around 10 mps was being pulled when the key was turned when I discovered the ground issue. I do remember the Run/Crank fuse clicking early in ny troubleshooting. The battery had a stronger charge during the earlier testing which might explain the difference.

My 6.2 Sierra Denali became hard to start which continued after replacing the battery. Then one day it would not turn over at all. I replaced the starter but still no crank. Also learned it is much easier to replace the starter through the wheel well than from below. Jumping the switched pins of the starter relay activated the new starter turning over the engine but not starting even with the key switch on. Before replacing the starter I remember that the run / crank relay was clicking and opening the throttle when the key was on. It was not clicking now so I made some test leads and found that the ground to the run / crank relay was weak. I found no continuity to ground through the ground pin of the relay socket. Checking voltage from the trigger pin of the relay socket to the ground pin of the socket I found 9.76 volts while testing from the trigger pin to the firewall ground I had 12 volts. I used a compressor to blow out the fuse box and that socket with no change. I disassembled the fuse box and could not find continuity from the ground pin of the socket to the pins on the bottom of fuse box. The black wire in the bottom connector closest to the run / crank relay did not have continuity to ground. The black wires in the other connector bundles did have continuity to ground and allowed for 12+ volts to pass. If I remember correctly that was connector X2. I found that shorting the switched pins of the run / crank relay opened the throttle allowing the truck to start and run when the key was turned. I also learned that the key switch would not turn off the truck with the run / crank relay socket shorted. Removing the wire across that socket would stop engine. As a short term solution I ran a ground wire from the firewall ground to the ground pin of the run / crank relay. This allows the truck to start and stop normally via the key switch. Can anyone tell me where the far end of the ground for the run / crank relay / X2 connector goes to? I suspect I have a ground issue there. Additional issues that have developed over the last year are that the oxygen sensors and fuel sender are not reporting. Fuse 8 oxygen sensor burns up when replaced. Thanks in advance for any advice. Also thanks to my brother who spent an afternoon troubleshooting with me.