Toyota Repair: 94 Toyota Corolla - High Mount Brake Light Stays On


Question
QUESTION: I have an automatic 94 Toyota Corolla DX.  When headlight is turned on, rear and top mount (center) brake light stay on EVEN when brake or hand brake not applied.  However, when brake is applied, no changes in brightness to center brake or rear light.  Brake light appears to stay on all the time whether car is in park or while driving.  

Checked the fuse and brake light switch.  No faulty parts were found.  Did noticed when brake is applied, the digital clock in the car goes dim.

Appreciate your expertise advice on this braking light issue.

ANSWER: Hello, try removing the "STOP" fuse in the fuse panel, do the brake lights still stay on? If not, disconnect the brake light switch, do the lights go out? It would help if can get a voltmeter or test light if we need to do further testing.

---------- FOLLOW-UP ----------

QUESTION: Removed "STOP" fuse, brake lights still stay on.  No blown fuse found. Replaced high mount brake light and stop fuse - same brake light issue.   

One other thing that I did observed, when headlight is turned off, the dashboard lights up when brake is applied and the digital clock goes dim. When brake is released, dashboard light goes out and digital clock light goes back to normal.  

High mount brake light and stop fuse were replaced.  Braking light problem still exists.  

Appreciate any advice on what further testings that I can do to isolate what causing this brake light issue.

ANSWER: Ok, the brake light circuit is picking up voltage from somewhere due to a short circuit between some wires. From what I understand it is the center brake light only that stays on, is this correct?

---------- FOLLOW-UP ----------

QUESTION: No.  Both high mount center stop light and both rear brake light stay on when I turned on the headlight.

Answer
Ok, thanks for the clarification, it sounds like there is some wiring issue at the rear, since removing the fuse does not turn the brake lights off, the brake light switch gets power all the time through this fuse. I would suggest removing all the bulbs at the rear inclusing the tail light bulbs, check each bulb socket including the center one for any signs of overheating or other damage. using a 12 volt test light check for voltage at the sockets, the green wires are for the stop lights, the white/black are ground, each tail light sub harness can be disconnected in the trunk, disconnect both tail light harnesses from the main harness, disconnect the center brake light as well, reconnect one side and see if the problem is still there if not reconnect the other side and then the center light this way you can at least isolate which side has the problem, I have seen many of the short sub harnesses cause this kind of problem, let me know how it goes.