Blown fuses or relays?

RICK SODER

MEMBER
2000 TOYOTA COROLLA
1.8L
4 CYL
2WD
AUTOMATIC
255,000 MILES

I was changing the alternator and did not disconnect the battery. I touched the alternator with the hot wire and it sparked. I lost the instrument panel, windows, and cannot move the shifter to put the car into gear. Did I blow a fuse or melt the system? Please help. Thanks.

2 Replies

SATURNTECH9

MECHANIC
30,869 POSTS

I would start by checking all the fuses. Especially the large fuses in the under-hood fuse box.

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Sunday, May 8th, 2016 AT 9:05 PM

CARADIODOC

MECHANIC
33,916 POSTS

That circuit is fused, most likely with a large fuse bolted in the under-hood fuse box. Typically it will be a 100 to 150 amp fuse. On older cars a fuse link wire was used. Those are simply a short section of smaller gauge wire but the insulation is special. It will not melt or burn. You test a fuse link wire by tugging on it. If it is still good, it will act like a piece of wire. If it is burned open, it will act like a rubber band. Fuse link wires take some time to burn open, so a sudden and quick spark will not do it. Bolted-in fuses will blow right away.

The clue to either fuse device being burned open is to check for 12 volts on that large bolted-on wire on the back of the generator. It must have 12 volts all the time. If you find it is missing, everything else protected by that fuse will be dead too.