Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum banner


  1. Blazer stalled while driving/ codes

    2006 trail blazer 5.3 4 wheel Driving home the other day, car just quit, it would crank but not start, towed it back to the ranch it sat for a while then thought I would give it a try and it started. Idled fine, engine light is now on. I don't yet want to drive it very far as I don't want to get...
  2. [SOLVED] DIY Throttle Position Sendor, code PO121 5.3 V8

    The 02-09 "How-To" and DIY Section
    I wanted to share some info on my successful fix for code PO121, indicating problems with the throttle position sensor. I followed Youtube instructions on removing, cleaning and replacing the throttle body. I was able to find just the sensor, part number 19-259-452. It was $43 delivered. Most...
  3. drive by wire

    OEM Issues
    Anyone know how to improve the response time of the drive by wire throttle. I am the type of driver who likes to gradually speed up but my Trailblazer doesn't respond well to a gradual take off.:bonk:
  4. 4.2L Throttle Body Replacement relearn?

    Can anyone tell me if a relearn is required after replacing the throttle body assembly on a 2004 Envoy 4.2L? The dealer told me today, I need replace mine because of a fault inside the TB itself for $533 installed. Thanks!
  5. Vibration

    4x4 Drivetrain
    Just had to have the transfer case module, and the throttle body assembly replaced on my '02 GMC Envoy. When I received it back from the dealership, it now has a vibration both when idle and in gear. Although the transfer case module was not working before the repair, the engine would start...
  6. P2138, P2135, P0641 TPS Problems

    OEM Issues
    I just got three codes on my truck. P2138, P2135, and P0641. I believe they all correspond with the TPS. I have changed the throttle body because it has an integrated TPS. About 24 hrs later it popped the same codes. What can be causing this?
  7. Trans Shifting Problem???

    Transmission Mods
    I ahve a 2006 Envoy Denali V8. When it is driven for more than 5 miles or when it gets up to interstate speeds it seems to shift hard from 1st to 2nd. If I just drive it around town then it has no problem. I have been to the transmission shop and they said it wasnt the transmission so Im...
  8. PO172, PO400---Garage says I need a new throttle body

    OEM Issues
    So the Envoy is begging for me to replace it, but I'm too stubborn because I love it. Last Friday on my drive from VA to PA (300miles) it wasn't running the greatest. Over the weekend the SES came on with a PO172 and PO400 code. I didn't have to go anywhere so I wasn't too worried. Monday comes...
  9. Poor Throttle Response in Low Range?

    Does anyone else notice a very sluggish throttle response when their TV transfer case is in Low Range? I have an '05 TB 4X4 that's completely stock except for some all-terrain tires (stock size). We take it on family trips to the mtns. out here in Idaho pretty often, and occasionally end up on...