Author Topic: Blew instrument light and ECM B fuse caused by headlight switch?  (Read 2246 times)

Offline robosmurf

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I was driving home Sunday, and about an hour into my trip I smelled that smell. The burning electrical smell.

Stopped at a rest stop and could really find anything thing, everything was working so I drove about another 30min and stopped for a bite.

When I came back out I had no instrument lights when I pulled my headlight switch, and crank with no start. Still had headlights. Checked the fused and the 5amp instrument fuse and 30amp ECM B were blown. Luckily I walked a couple blocks to the parts place and grabbed a pack of fuses. I replaced the ECM B with no problems but the instrument fuse kept blowing, so I just drove home with no gauge lights. I verified tail lights and brake lights before hitting the road.

Monday I was off so I dove in. I pulled the headlight switch and could smell the burnt right away. I took it apart and found this on the rotor




I cleaned it all off and lubed up the sliders in the switch with some bulb grease and everything seems to be working.

Would this blow the ECM B fuse? It's right next to the instrument fuse.
84 c20 Camper Special
454ci with TBI

Online bd

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Re: Blew instrument light and ECM B fuse caused by headlight switch?
« Reply #1 on: October 17, 2017, 09:28:55 PM »
Check for shorted wiring behind the dash or bare metal touching the PC board.  Take a close look at the rivets retaining the w/w rheostat to the ceramic block to make sure they are tight.
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline robosmurf

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Re: Blew instrument light and ECM B fuse caused by headlight switch?
« Reply #2 on: October 17, 2017, 09:41:23 PM »
I needed to pull the cluster and clean it anyway!

84 c20 Camper Special
454ci with TBI