I'm wanting to hook up a 3rd brake light on my 89 pickup. Where is the best place to hook it up? My service manual is not helping me. Thanks.

Best place that is a hard question to answer.

Do you mean best place in the electrical sense ??

The best place as far as access to make things simple ??

Your starting from scratch just where are you installing the light ??

I just plugged my light bar into the trailer light plug that way I can remove it and put it on the trailer

Brake light switch

Trailer plug if you have one

Anyplace in the brake light circuit

I'm using a factory light in the the factory location. Currently the wires are routed to behind the dash with about 8 feet of extra lead. I would like to keep this simple if I can.

Pin 5 (switched fused +) and pin 17 (-) of connector I1 under the passenger's seat.

Thanks for the info.

One thing I found though is that there is no Pin 17. My plug only goes to 9.

Hmm, it could be a different year's plug. If you can post a pic of your plug there, that would be great. In general, it should be the green/white-stripe (switched +) wire and white/black-stripe wire (ground).

The connector under the seat is BG1, and in my '94 EWD it's shown as a 14-pin connector, with the Stop lamp on pin 5. Go figure.

Even in '94, the wire for the stop lamp is G-W. But this isn't rocket surgery. Just test for voltage to ground on all 9 pins. The one that goes to 12v when you step on the brake is the one you want.

That's what I ended up doing. At first I wanted to try keep the wiring as short as possible but this way worked. Now that this is done the only things left to do in the interior are a new radio and fix the seats(they are old and nasty).