rpope904

My neighbor asked about a problem he is having, its on an 87 bronco, full size. He said someone put his battery in backwards, and now its not getting any power to anything, the lights wont even come on.. I don't know too much about these trucks, where would be a good place to start in looking for the problem?

847alexc

First thing to do is to ensure that it is in properly now. Make sure that Negative goes to ground. It is quite possible that something got messed up by switching the battery terminals.

On that vehicle, my largest concern would be the computer and the diodes in the regulator.

To begin, use a test light to perform some simple tests (10$ at walmart).

1) first test across battery terminals, does the battery still have power or even function.

2) test the positive cable to ground, does the positive cable have continuity, and does ground have charge. repeat this test at any accessible point on the positive cable. You are looking to see if this got fried. These old vehicles didn't have fusable links, instead the wires would burn up (sometimes inside the insulation without visual evidence).

3) test for power across several fuses, and test the main leg of the fuse box to ground, to see if it is receiving power.

beyond these things, you would need someone who had this same problem on the same year to see where exactly the circuit would break first. The weakest link if you will. It varies from year to year, model to model.