87 Carerra Cab battery good, but no power

[tcheat]

Newbie here. I have a new to me 1987 Carrera Cab. I got caught in a downpour last night. When I tried to start it later, it cranked once and then everything went dark. No lights, no seat belt buzzer, no nothing.

I've checked all the fuses and they look fine, including the ones in the engine compartment. The battery is at 12.6 volts and the cables are tight on the battery posts.

I'm sure that this is something easy, but I'm at a loss. When I turn the key, I get nothing at all, anywhere. Any ideas?

Thanks.

[911obgyn]

Remove the battery connectors and clean them and check the ground to the body from the battery, then check for power at the fuse block, a test light works good for this stuff.

[gomezoneill]

Although the cables are tight there could be corrosion between the cable and post. Remove and clean with wire brush. Retighten try again.