Is Your 2004 Buick Rainier Running Rough?
If you’re dealing with frustrating issues like a persistent check engine light, erratic engine behavior, poor fuel economy, or even a no-start condition, a failing Powertrain Control Module (PCM) could be the culprit. As the central computer of your vehicle, the PCM controls everything from fuel mixture and ignition timing to transmission shifting. When it fails, it can cause a wide range of problems that are often difficult to diagnose, leading to costly and unnecessary repairs.
This replacement PCM, part number 12586242, is the definitive solution for your 2004 Buick Rainier and a wide range of other GM trucks and SUVs from that model year. Don’t let a faulty computer keep your vehicle off the road. We provide a reliable, plug-and-play solution to get you back to smooth and dependable driving.
From the Diagnostic Bay
We had a 2004 Trailblazer EXT come in with a bizarre issue: it would randomly stall at stoplights, but only after it was fully warmed up. There were no consistent trouble codes, just a generic communication error that would pop up intermittently. After checking fuel pressure, sensors, and wiring harnesses for hours, we finally swapped in a known-good PCM. The problem vanished instantly. The original module had an internal fault that only manifested under specific temperature conditions. This is a classic example of how a failing 2004 Rainier PCM or its equivalent can create phantom problems that are nearly impossible to trace without replacing the unit.
Common Symptoms of a Failing 2004 Rainier PCM
- ✔ Persistent Check Engine Light (CEL) illumination
- ✔ Engine stalling or shutting off while driving
- ✔ Rough idling or misfires
- ✔ Noticeable decrease in fuel efficiency
- ✔ Harsh or incorrect automatic transmission shifting
- ✔ Failure to pass emissions testing
- ✔ Complete no-start condition where the engine cranks but won’t fire
The Perfect Fit, Programmed for Your Vehicle
Forget the hassle and high cost of a dealership visit. This module is a direct replacement for service numbers 12586242, 19299226, 89017738, YFKD, YFKF, YFKH, YFKJ, YFKX, YFXL, YFXM, YFXN, YFXP, and YHTN. To ensure a seamless installation, we program the module specifically for your vehicle using the VIN you provide at checkout. This process loads the latest GM-certified software and calibrates the computer to your vehicle’s exact specifications, making the installation process as simple as swapping the part. No additional programming or dealer visits are required.
Do I need to have this module programmed?
No. We handle all the programming for you before shipment. Simply provide us with your vehicle’s VIN during or after checkout, and we will flash the module with the latest official GM software for your specific vehicle. It will arrive ready to install.
Is this a difficult part to install?
For most of the compatible vehicles like the Rainier, Envoy, and Trailblazer, the PCM is located next to the airbox in the engine bay and is relatively easy to access. It typically involves disconnecting the battery, unplugging the electrical connectors, and unbolting the module. Basic hand tools are all that’s required. However, we always recommend consulting a service manual or a professional technician if you are not comfortable with the procedure.
Will this fix my check engine light?
If the check engine light and associated symptoms are caused by a faulty PCM, this replacement part will resolve the issue. It’s crucial to ensure that the root cause of the problem is indeed the computer and not a faulty sensor or wiring issue. We recommend a proper diagnosis before ordering.
What is a service number?
The service number (e.g., YFXL) is a specific identifier used by GM for the software and hardware version of the module. This listing is compatible with a wide range of service numbers, as listed in the description. As long as your part number or service number is on our list, this module will work for you once programmed to your VIN.
Is a security relearn procedure required?
In many cases with these GM vehicles, a security relearn (also known as a CASE relearn or Passlock relearn) may be necessary after installation for the vehicle to start. This is a simple procedure that typically involves turning the key to the ‘ON’ position for 10-15 minutes, then off, and repeating two more times. Instructions for this can be easily found online or in your vehicle’s service manual.