Brake Lights stay on?

TPHELPS98

MEMBER
2002 NISSAN PATHFINDER
3.5L
6 CYL
2WD
AUTOMATIC
210,000 MILES

I replaced the alternator and brake booster. Everything seemed to go as expected. The engine idles smoothly under load and new alternator supplies correct voltage with no issues. While testing the work it came to my attention that the brake lights were staying on, the brake pedal light switch was not functioning.
Replaced brake light switch with new part, however, the lights remain on. Can't figure out why power is not being disabled.
Removed new switch and tested with DMM. It is functioning correctly. Any help would be greatly appreciated.

3 Replies

JACOBANDNICKOLAS

MECHANIC
108,192 POSTS

Hi,

Do the brake lights turn off if you disconnect the brake light switch? If so, there must be an adjustment issue. If they don't, then we have a short to power at some point.

When you tested it, did you confirm the red wire with a black tracer has B+ voltage? It should at all times. The green wire with the yellow tracer should only receive power when the switch is actuated. That is the only power path for the brake lights unless something different is shorted.

So, you checked the switch with the DMM. I suspect you checked for continuity when the switch was open and then closed. Pay attention to how far the switch moves when the switch becomes open. Then, reinstall the switch and check if it is traveling far enough to open/break the power supply.

If you want to confirm the issue is at the switch, simply disconnect it and the lights should turn off. If they do, the switch needs to be adjusted.

Let me know.

Joe

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Monday, October 17th, 2022 AT 7:03 PM

TPHELPS98

MEMBER
2 POSTS

Thanks for your speedy reply. I found the problem not long after I texted you. I went back out and started over. Pulled the switch and retested for functionality. Switch opened and closed circuit correctly. I went to test the plug again and realized I hadn't really done an Indepth visual inspection of the plug, only metered with DMM. One side of the bifurcated pin captured on the plug had been deformed and wasn't making a solid connection. I took a small jewelers screwdriver and reconfigured the connector. Did the trick. All is working as designed.
Once again, thanks for your quick response. I'll definitely be using you guys as a resource in the future.

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Monday, October 17th, 2022 AT 8:51 PM

JACOBANDNICKOLAS

MECHANIC
108,192 POSTS

Hi,

Thanks for the update. I'm glad you found the issue. Wiring can become a nightmare.

Please feel free to come back anytime in the future. You are always welcome.

Take care,

Joe

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Tuesday, October 18th, 2022 AT 8:13 PM