OH YEAH, I GOT AN ELECTRICAL QUESTION! FOR THE THIRD BRAKE LIGHT, Props to ANSWER!

[V6UnderPressure]

Ok fellas I got one for ya! Your gonna love this one, and its driving me crazy. A while back I put too bright of a bulb in my third brake light housing. Well I burnt something because the brake light went out. Now, I did all the voltage checks and I am getting 12.20V at the socket, at the wires and at the connector. So What gives? I even cut the wires going to the socket and pressed em to the battery and it lights! HEHE what the hell is going on. I tried everything, this thing is getting 12V so why isnt it lighting? I replaced the brake light switch on the pedal arm, so that is new but that didnt fix the problem. Any ideas? I heard something about a diode but where is it? GOOD LUCK!

Scott

 

[FlyinGN]

Scott, heres my take.. My 3rd lite quit working and when I tested it at the socket I too got 12v, but the bulb would NOT light. I replaced the socket and still nothing. I had a friend with a shop manual take a look and we traced the power lead back to the brake switch. You said you changed it. Is it a new one?? The little contacts in the switch would allow 12v to pass and showed 12v with a meter BUT under load, the contacts could not push voltage past it to lght the light. I don't believe that there is any diode in the circuit. At least none that I seen in the wiring diagram.

 

[salvageV6]

Frank is right with this one. Not only do you need the +12 voltage there you need some current behind it to light the bulb. The meter will draw very little current to register +12 volts accross the wires.

Read the voltage on the wiring after you put a lamp accross the wires. Bet it doesn't read +12 again.

Sounds like the switch is bad to me. Or a very bad ground connection.

 

[V6UnderPressure]

FlyinGN, yes switch is brand new from the local auto store. Nothing seems to make sense. I agree that current could be the issue. There is obviously a mishap somewhere from the connector in the drivers side trunk all the way to the switch. Im thinking maybe fried wire now? The wire is a little black, but Like I said it does have contacts. I am starting to think that it is not the ground (because I tested it) but the blue wire, because I switched the blue and brown (on the connector) and when the lights came on, it lit up, so theres power there. maybe I should link it to my lights? Hell might look cool being that it says "got boost?". Ill see , do a few more tests and hopefully end this nightmare. Thanks guys

Scott

 

[salvageV6]

In the LH side of the trunk where the hotwiring trigger and fuel pump power all go check for the following.

Use a good bulb with test leads such as an 89 trunk light bulb.
Put one lead to ground and the other on the stop feed wire in the following connectors with the following colors.

Oh, don't forget to put a brick on the brake pedal too! Switch must be on of course.

Connector C780 is a 3 pin connector fed out of the multipin C320 connector. Also check the ground strap G177 bolted in the trunk at that area.

Now out of the 3 pin connector above the multi-pin one the wire you are looking for is the light blue one that goes to the lamp socket on the parcel shelf. It is in cavity C of the connector.

Next if still dead try the test lamp at the lower multipin connector C320 the wire is pin F and is light blue with a black stripe.

If still dead you gotta test next up near the fuse box.

 

[V6UnderPressure]

Is there a separate fuse for the third brake light? I always thought it was part of the brake/turn signal, housing?

Scott

 

[salvageV6]

Nope stop/haz fuse, same one as the other stop lights.

Same orange feed wire to the switch as well.

Take a good 89 lamp get some leads on it and go testing.