Blown or missing gauge fuse causes strange symptoms on a 2007 Yaris hatchback

[vandallen]

I recently went through some strange electrical symptoms when my gauge fuse inside the cabin was not present.

First the ac fan quit running. Then the engine overheated, because the radiator fuse wasn't running.

The battery light would come on when I turned off the blower switch. When I turned the blower fan switch to off the engine ran terrible and gave P0300, PO301, 02 03 and 04 codes.

It turns out the battery won't charge if the Gauge fuse is open. Then when the battery voltage gets too low all sorts of weird things start happening.

I recharged the battery and replaced the fuse. Somehow it seems when I was checking the fuses inside I put the gauge fuse in an empty spot so the gauge fuse slot had no fuse in it.


I never did find out why the ac fan quit running. I think it had something to do with the battery getting weak.

[CTScott]

Some of that makes sense, as the GAUGE fuse feeds the coil side of the relay for the AC blower and also feeds the control signal for the voltage regulator module of the alternator.