1997 Gmc Z71 1500 Transmission Lockout

[z71owner]

Hi.

 

Applying pressure to the brake and trying to shift out of park as everyone's done a million times suddenly isn't working anymore. I assume this is common and well documented?

 

Two questions: How do you repair this, assuming it's mechanical or replace it assuming it's electronics, and two, can you force it when it's "locked" if you're stuck in a parking lot somewhere, or will this cause damage?

 

Thanks!

[ryank1]

The 1st place to check, is the operation of the btsi switch (brake trans interlock), as far as by passing it, the only trick I know is to set the parking brake and disconnect the shift cable at the trans and move the switch manually.

[staruser]

I had the same problem. It would only happen when the truck was parked facing downhill. I had to push the truck uphill just enough to disengage the transmission out of park. Now, I set the parking brake and then release the the brake pedal after I put the tranny in park. That seems to work.

[Burbman]

Make sure your brake lights are working. If a fuse is blown or the brake light switch is bad on the brake pedal, it won't complete the circuit to the trans interlock.

[asilverblazer]

I had the same problem. It would only happen when the truck was parked facing downhill. I had to push the truck uphill just enough to disengage the transmission out of park. Now, I set the parking brake and then release the the brake pedal after I put the tranny in park. That seems to work.

 

This is from the truck resting/leaning/rolling on to/applying excess pressure on the parking pawl. And not a specific problem to the shift interlock.

[resq-comm]

i just replaced my brake light switch last weekend. it was about 8 dollars at auto zone. make sure you pick up a new retaining clip too, here in Tampa i had to get it from the dealer ( a whopping 97 cents!!) it is a tight fit, at least on my 98 Sierra 2500. i was able to get it to hold on a temp basis, but the new one is going in this weekend. the other issue i had with the replacement was the housing was not as strong as the original, the metal tab that pushes the switch fell out after the first test. i ended up having to open both the old switch and the new and swap out the guts. i could have probably just opened the old one and cleaned the contacts. there are slight metal burns on the plates from the arc.

 

best of luck, it's not hard to do, just a tight space and frustrating when you are on limited time and light.

 

i do agree with everyone else also, check first to see if you have brake lights. if not, check the fuse first, switch second.