2001-2002 Isuzu Rodeo Sport brake light issue

Troubleshooting Electrical & Wiring
1

Before you post, fill this in — it gets you answers faster:

  • Year: 2001
  • Model: Rodeo Sport
  • Engine: 3.2V6
  • Transmission: Automatic
  • What changed recently (if anything): Nothing
  • Symptoms / what it’s doing: Brake lights go out when brake pedal depressed, only when the lights are on.
  • Codes (if any): None
  • What you’ve already tried: Nothing

Okay, this is my neighbor’s truck, so I don’t know much and will need some help with trouble shooting.

Per neighbor, the issue is that with the running lights on, the taillights work normally. With the lights turned all the way on, the taillights illuminate, but when you step on the brake, the drive side light goes all the way out. I know I’ve read about this issue many times in the past, but since I wasn’t the one with the problem, I don’t remember the solution. It seems to me it is not likely to be the bulb since the light at least one of the filaments works, it should never go completely out.

Could we get some help with initial diagnosis? Let me know if there is more info you’d like and I can find out. He should have the tools for any kind of electrical testing if needed.

Thanks in advance.

2

Likely a bad ground. Quickest way to prove this is to manually provide a know good ground to the circuit temporarily.

3

Thanks for giving us a place to start. I shared the post with him as well.

4

He said he started with changing the bulb, and now everything is acting correctly. Completely factory truck, no tow hitch, no tow wiring. Hopefully it was just a bad bulb, but the symptoms still sound strange to me.