PCM B 20 amp fuse blew (only once) 98 Tahoe

[drichers]

Last week the fuse blew. I replaced it and it has been fine since. I measured the current through that fuse and it was never over 10 amps. I have a long trip planned pulling my camper and I'm a bit worried it will happen on the highway. I have read the threads on this. Any ideas?

girl from Memphis

[joel macneill]

Is there any metal parts near the pcm that were not factory? maybe a metal seam for a body structure point? It sounds like the fuse is blowing due to an intermittent short and those are the worst to diagnose. Did the fuse blow during startup, taking a corner, full throttle? If you narrow down this to a possible clue then maybe you can track other things like harnesses rubbing on suspension, or firewall, or possibly the engine itself. The computer fuse is likely blowing from one of these because if it were a shorted sensor for example, then the computer would enter a failsafe mode and just not work with no data communication. The good thing is that the computer is relatively easy to access.

[drichers]

nothing new installed recently except the starter and rechecked the wiring to that yesterday. It blew when i was slowing down at a stop sign.

[777stickman]

This fuse powers 2 things.

1. Constant 12v to the VCM.
2. Power to the fuel pump thru the pump relay.

So, I would suggest that the wiring from the pump relay to the fuel pump be examined very closely. The pump power wire is grey. The connector at the pump has been known to cause issues.

Best of luck.