87 Corolla Electrical Problems

[Ladyfsh]

This is a Corolla FX16, 4AEG, DOHC, which I purchased a few months ago. My mechanic is methodically going through and replacing/fixing all noticeable issues such as oil leaks and worn hoses. So far, it has gotten a new distributor, cap, plugs, wires, gasket seal, several hoses replaced and all motor/transmission mounts replaced, due to an incredible rough idle and vibration (which reduced significantly, not did not resolve completely). Now the issue is electrical. The 7.5 amp fuse for the “gauges” blows as soon as you turn the key. This disables the gas, RPM and temperature gauges, as well as the heater/ac blower and rear defroster. Additionally, the back up lights do not work and yes, I’ve changed the bulbs just to make sure. I’ve seen a couple postings indicating the back up lights could be the culprit, that somehow, the gauge fuse and reverse lights are tied together. At first we thought the instrument cluster was dead, but replaced the gauge fuse right after I bought it and it worked for about a week and a half, then blew and has not worked since. Suggestions?

[REN69]

Sounds like you may have wires that are bare, when they touch metal they blow the fuse. Look at all the wiring and repair any that are cut or bare in some spots.

[Ladyfsh]

After tearing the interior apart two weekends in a row, I gave up and took it to an electrical shop. Took two hours but they found a frayed wired in the wiring harness going into the transmission. Wasn't even in the cabin. All fixed, but still no back up lights

[openflame06]

As ren69 mentioned its always a good idea to check for wire to metal shorts. I had a similar problem a while back where the dash would constantly read full petrol and high temperature. It turned out that the horn was actually bent back onto the chassis of the car and the wire on it was shorting to the car.

Fixed that up, got a new dash and it was all fine