This 1999 Chevrolet Tahoe came in with a complaint that the ECM 1 fuse in the under hood fuse box would blow, which of course causes a no run condition. Usually five to ten minutes after a cold start. That in itself is enough of a clue to me to start looking around the exhaust and sure enough there it is. The harness was not properly secured after an engine exchange and the harness for the crank sensor is shorted out on the passenger exhaust manifold.
I disconnected the wiring harness from the crank sensor, power steering pressure sensor and ground locations. I then pulled the harness up so that I could work on it easier. The picture below shows the melted loom and exposed wiring.
The only wire that was actually damaged was the red power supply wire for the crank sensor.
I replaced the damaged wire.
Placed the wiring back inside the loom and wrapped the whole thing with metal tape to reflect the heat. I then routed the harness correctly down to the lower side of the engine and secured the harness in the factory retainers that were still in place. Whoever had done the engine work was in too big of a hurry to put the wiring back correctly. Their loss is my gain.