Piston Slap: The Backwards Ascent?

Sajeev Mehta
by Sajeev Mehta

Chris writes:

2006 Isuzu Ascender: the reverse lights are on while driving forward, in drive. I got pulled over for this. Anybody have an idea why they stay on when in drive? How I can troubleshoot this issue?

Thanks for your time.

Sajeev answers:

Usually my gut reaction is what I elucidate in a Piston Slap reply, but the obvious reverse switch for your vehicle doesn’t exist. Damn my incorrect gut!

But that’s fine, parts get consolidated as features integrate: no more individual switches for neutral safety and reversing, new vehicles put it all in a single Parking/Neutral Position and Backup Lamp Switch. Aside from the obvious need to check the wiring for damage/hackery, either the Body Control Module (BCM) or that switch are to blame. Check out RayVoy’s reply to this thread: does your gear indicator in the gauge cluster also read incorrectly?

So it’s your call, either you replace the switch or test the BCM to ensure buying the switch is the correct repair.

Judging by the hits on Google for failing switches, by its affordability (under $60, probably less than the BCM test at any shop) and by my experience with it being a wear item (changed my 1995 Mark VIII when it was 16 years old), you would be forgiven for replacing it prophylacticallyand hoping for the best!

Off to you, Best and Brightest.

[Image: GM]

Send your queries to sajeev@thetruthaboutcars.com. Spare no details and ask for a speedy resolution if you’re in a hurry…but be realistic, and use your make/model specific forums instead of TTAC for more timely advice.

Sajeev Mehta
Sajeev Mehta

More by Sajeev Mehta

Join the conversation
9 of 29 comments
  • CobraJet CobraJet on Jul 27, 2018

    When I was a teenager, the backup lamp switch failed on my 1966 Mercury Comet. I wired the lamp circuit to a toggle switch that I mounted under the dash. If I wanted backup lamps, I just flipped the switch. It was sometimes handy when being tailgated. I would flip the switch on and off. This usually made the car behind back off, not being able to figure out what was happening.

    • See 3 previous
    • Erikstrawn Erikstrawn on Jul 30, 2018

      @RHD I met a trucker once who swore by peanut M&Ms. He said if he tossed one out his cab, the wind down the side of the trailer would accelerate it enough that it could crack a windshield.

  • Turbo_awd Turbo_awd on Jul 27, 2018

    In my childhood, two countries and a continent ago, in a simpler time.. Around 1977-1978, our Renault R16-TS (maybe a 1970? or a 68?) had needed a new bulb of some kind - I forget which, maybe rear brake / turn signal? And apparently, the wrong size / type had been installed, and afterwards, when depressing the brakes, the main headlights would come on (or possibly reverse lights). Installing the correct bulb fixed it.

  • Cimarron typeR Cimarron typeR on Jul 27, 2018

    I remember on our old 1980 Accord 5mt that my brother and I drove in HS in the 90s (tan over tan btw) developed a problem where the brake lights would stay on permanently while we were at a regional tennis tournament with 2 other buddies. We rigged up a system with 2 tennis racket bag straps that the backseat passenger would tug on the whole drive home. It ended up being a worn out solenoid type switch on the brake pedal when we took it to the shop.Fun times.

    • JohnTaurus JohnTaurus on Jul 28, 2018

      I have used a tack or other small piece of plastic/metal/rubber etc to temporarily repair a faulty brake switch such as that.

  • Vulpine Vulpine on Jul 28, 2018

    Once a very common problem with column-mounted automatic levers. Switch would slip out of position and have the reverse lamps on while driving forward. I used to see this a lot in the 60s vintage cars, especially.