If your 2006-2009 Pontiac Montana is suffering from unpredictable shifting, getting stuck in gear, or has a persistent check engine light, the cause is very likely a failing Transmission Control Module (TCM). As the electronic brain of your automatic transmission, a faulty TCM can make your family minivan feel unreliable and unsafe. I’ve seen it countless times in my 20 years on the job: a perfectly good transmission sidelined by a failing computer. This VIN-programmed T42 TCM, part number YNXS, is the definitive solution to restore smooth, dependable performance without a costly trip to the dealership.
This module is a direct-fit replacement, specifically programmed to your Montana’s unique Vehicle Identification Number (VIN) before it ships. This critical step ensures that all factory shift points, torque converter lockup strategies, and diagnostic parameters are perfectly matched to your vehicle. The result is a true plug-and-play installation that resolves common communication and performance-related Diagnostic Trouble Codes (DTCs) right out of the box. Don’t let a faulty module dictate your driving experience; get the reliable fix your vehicle deserves.
From the Diagnostic Bay
I remember a customer with a 2008 Montana SV6. They were frustrated because the van would occasionally slam into gear, but only after it had been running for about 20 minutes. Other times, it would refuse to shift out of 2nd gear. They’d been to two other shops that couldn’t replicate the issue. When they brought it to me, I suspected heat-related failure in the TCM. We swapped in one of our pre-programmed T42 modules, and the problem vanished instantly. It’s a classic symptom—internal circuit board components fail when they get hot, causing intermittent issues that are a nightmare to diagnose if you don’t know what to look for. This part solves that headache.
Is Your Pontiac Montana Showing These Signs?
A failing TCM can manifest in several ways. If you’re experiencing any of the following, it’s time to consider a replacement 2006-2009 Montana TCM.
- ✔ Harsh, jerky, or delayed gear shifts.
- ✔ Vehicle is stuck in “limp mode” (usually 2nd or 3rd gear).
- ✔ Check Engine Light or Transmission Warning Light is illuminated.
- ✔ Diagnostic codes stored, such as P0700 (Transmission Control System Malfunction), P0750-P0758 (Shift Solenoid Errors), or other transmission-related faults.
- ✔ Failure to upshift or downshift properly.
- ✔ A noticeable decrease in fuel economy.
- ✔ The transmission feels like it’s slipping between gears.
Easy DIY Steps to Restore Your Montana’s Shifting
Replacing the TCM on your Montana is a straightforward job that most DIYers can complete in under 30 minutes with basic hand tools. This module is conveniently located and designed for easy access.
- Safety First: Always disconnect the negative terminal from your vehicle’s battery before starting any electronic component replacement.
- Locate the Module: On the 2006-2009 Pontiac Montana, the TCM is typically found mounted to the driver’s side (LH) strut tower in the engine bay.
- Disconnect and Remove: Carefully unplug the electrical connectors. Use a small screwdriver to release the locking tabs if necessary. Then, unbolt the module from its mounting bracket.
- Install the New TCM: Bolt the new, VIN-programmed module into place and securely reconnect the electrical harnesses. You should hear a click as they lock in.
- Final Steps: Reconnect the battery terminal. While the module is plug-and-play, it’s good practice to use a basic OBD2 scan tool to clear any old fault codes from the vehicle’s memory.
Verified Vehicle Compatibility List
This T42 TCM (part YNXS) is a guaranteed fit for the 2006-2009 Montana TCM and is also compatible with a wide range of other General Motors vehicles. Please verify your model and location below:
- Pontiac Montana (2006-2009): Transmission; (LH strut tower)
- Chevrolet Cobalt / Pontiac G5 / G6 / Pursuit (2006-2010): Transmission; (LH strut tower)
- Chevrolet HHR (2006-2011): Transmission; (LH engine compartment)
- Chevrolet Impala / Monte Carlo (2006-2011): Transmission; (lower air cleaner housing)
- Buick Allure / LaCrosse (2006-2009): Transmission; (lower air cleaner housing)
- Chevrolet & GMC Full-Size Trucks/SUVs (2007-2013): (e.g., Silverado, Sierra, Tahoe, Yukon) Transmission; (next to battery)
- Chevrolet & GMC Full-Size Vans (2006-2014): (e.g., Express, Savana) Transmission; (RH engine compartment)
- …and many other GM models listed in the original fitment data.
Frequently Asked Questions
What does “VIN Programmed” actually mean for me?
It means we load your vehicle’s specific VIN into the module before shipping. This ensures it has the correct software and calibration for your exact transmission and engine combination, making it a true plug-and-play part. You won’t need to pay for expensive programming at a dealership.
Is this part difficult to install on my Pontiac Montana?
Not at all. For the Montana, the TCM is located on the driver’s side strut tower, making it very accessible. With basic tools, most people can swap it out in under 30 minutes. Just disconnect the battery, unplug the old module, unbolt it, and reverse the process with the new one.
Will this fix a P0700 trouble code?
A P0700 code is a general fault code indicating the TCM has detected a problem. In many cases where the TCM itself is the source of the electrical fault, replacing it with this module will resolve the P0700 code and any related solenoid codes.
Do I need to return my old TCM (core charge)?
No, there is no core charge for this part. You can keep your old module or dispose of it, saving you the time and hassle of a return shipment.
What kind of warranty is included?
This Transmission Control Module comes with a one-year warranty, giving you peace of mind and confidence in your repair.