1993 240 Third brake light on dimly with headlights lights on

[Michael92]

Hi so I noticed my 1993 240's 3rd brake light turned into a 3rd taillight recently when the headlights were on. The brake light would function normally but would be on low-light whenever I was off the pedal. I fixed it. It ended up being the neutral safety switch, if any of you ever experience this problem. Having a 3rd taillight was cool but decided to go back to how it was designed.

 

[dl242gt]

Good one. Those are independent circuits from each other. Really strange that it would affect tail lights to brake light via the neutral safety switch.

 

[Michael92]

Just circling back to let you know that I was wrong about the Nuetral safety switch. While it did fix my problem or mask it, the real culprit was an LED bulb I was using in my third brake light. When I swapped in an incandescent, the problems went away. SO, safety switch not the problem but Chinese LED bulbs. Also with that led bulb in the 3rd brake light, it was also lightly powering my brake lights when in Reverse. Anyway, I suppose led bulbs can create some strange problems.

 

[Khrrck]

I would check to make sure you don't have a grounding issue. It sounds more like one of your taillights has lost its normal ground connection and is grounding backwards through the other bulbs.

An incandescent bulb would mask this problem because it takes more electricity than the LEDs do to actually make visible light. It's possible you haven't actually fixed the issue yet.

 

[bobxyz]

^^^ +1

I'd guess a poor ground wire and feeding back voltage through the dual-filament brake/taillight bulbs. You could see if the center light goes out after removing one or both of the left/right brake bulbs.

(Note: the '93s have a shift lock solenoid connected to the brake circuit, so your original diagnosis was a possibility.)

 

[Michael92]

^^^ +1

I'd guess a poor ground wire and feeding back voltage through the dual-filament brake/taillight bulbs. You could see if the center light goes out after removing one or both of the left/right brake bulbs.

(Note: the '93s have a shift lock solenoid connected to the brake circuit, so your original diagnosis was a possibility.)

https://turbobricks.com/index.php?t...hifter-lock-wount-unlock-occasionally.235343/

Thanks for the hint. I was able to determine that the shift Lock relay needed to be removed since I removed the device from the shifter. Now the problem is actually fixed