porcelain

After working out my problem with the blinkers I was driving to work today and when I got to work I shut the ignition switch off all the way and noticed the "Brake" light is on with the engine off. So I started her up again disengaged the ebrake and the light shut off. Then again with the ebrake disengaged I shut the engine off and the light came back on. It wont come off until the engine stops turning (pulled the key out quickly to be sure).

Any ideas on what I should look for when I get home tonight? My fluid is good and full. The only thing I have done recently is the ZUK mod and fixed the turn signals on my truck. Kind of stumped as to what can cause this.... I searched but havent found anyone with this problem. I will start by reviewing the blinker work I did just cant imagine it would cause this since after I had "fixed it" I tested everything and there were no problems... until this morning. Any Ideas?

wyoming9

iTrader: (1)

The light is on with the key out of the ignition

was it on while you were driving ??

Could be either of those two switches have contacts burnt closed.

Was the E-brake engaged Light will be on.

If it was not fully off like if the cable is fraying and not allowing it to open the switch the light stays on.

This is powered by the charge fuse. Some how this circuit is getting powered without going through the switch unless it is just a bad ground coming into this circuit and lighting the light.

Without the electrical diagrams for a 89 I would just be guessing.

porcelain

With the key out of the ignition it stays ON like when I park my truck for the day, its on. While i'm driving and everything is on and running its OFF.. unless I pull/engage the ebrake with the truck still running. It's very strange... what would cause the light to stay ON with everything shut down? Brake fluid reservoir low sensor grounding or something? I really appreciate your help/reply wyoming9...

Hadmatt54

I'm three weeks late on this, but I was away working on Hurricane Sandy damage. So if this is still a problem then here are some ideas.
wyoming9 said:
The brake light is actually fed from the 15A. Engine fuse which feeds all of the circuits and gauges in the combination meter. I think what wyoming9 might have been referring to is the fact that when you turn on the key the brake light and the charge light come on until the engine is started. When not charging the alternator is a path to ground causing these lights to be lit. Once the engine starts and the winding of the alternator is excited and starts charging the path to ground is no longer available and these lights go out because there is a diode after each light in the circuit. These diodes are both now reversed biased and that prevents backfeed.
The engine fuse is hot only when the key is on, so somewhere you are getting a feed into this circuit from a circuit that is hot with the key off.
There are several:- headlights, stop lights, hazard lights, horn, dome lights, door locks, rear window and efi.
If it is a backfeed then the diode in the printed circuit that is supposed to prevent backfeed is shorted and if there is a backfeed present through the bulb the circuit will be completed by a ground path through the voltmeter.
The next time it does this, the easiest check would be to unplug the three wire plug off of the alternator and see if the light goes out. At the same time you can check the red wire on the plug for voltage to ground, there shouldn't be any if the key is off as this comes from the 15a. engine fuse. If the red is okay and the light goes out when you unplug the wires from the alternator then my guess is you are getting a backfeed from the voltage regulator in the alternator and you have a shorted diode in the cluster.