Is Your 2004 GMC Safari Running Rough? A Failing PCM Could Be the Culprit.
As a technician with over two decades of experience under the hood, I’ve seen countless vehicles with baffling electronic issues. If your 2004 GMC Safari is experiencing problems like stalling for no reason, a persistent Check Engine Light, poor fuel economy, or a complete no-start condition, the Powertrain Control Module (PCM) is a primary suspect. This module is the brain of your van’s engine and transmission, and when it fails, it can cause a wide range of frustrating and hard-to-diagnose symptoms.
This isn’t just a replacement part; it’s a complete solution. We take the guesswork and the expensive trip to the dealership out of the equation. Each 2004 GMC Safari PCM is professionally flashed with the latest official GM software updates. All we need is your vehicle’s VIN at checkout. This ensures that when the module arrives, it’s a direct-fit, plug-and-play component specifically configured for your van’s systems. You’re not just buying a part; you’re buying a reliable fix that restores your vehicle’s original performance and dependability.
A Technician’s Notebook: The Intermittent Stall Case
I once had a 2004 Safari in my bay that was driving the owner crazy. It would run perfectly for days, then suddenly stall at a stoplight and refuse to restart for 10-15 minutes. No consistent codes were stored, just a history of random communication errors. After verifying the fuel pressure and ignition system were solid, I suspected the PCM. Heat soak was likely causing an internal solder joint to fail intermittently. We installed a VIN-programmed PCM just like this one, and the problem vanished instantly. It’s a classic failure mode for these modules, and this part is the definitive fix.
Common Signs of a Failing PCM
If your vehicle is exhibiting any of these behaviors, a faulty engine computer is a likely cause. Replacing your 2004 GMC Safari PCM can be the solution you need.
- ✔ Check Engine Light is on with codes like P0601, P0602, P0606, or U-series communication codes.
- ✔ The engine cranks but refuses to start.
- ✔ Unexplained drops in fuel efficiency.
- ✔ Rough or erratic idling and stalling.
- ✔ The transmission shifts harshly or at the wrong times.
- ✔ Failure to pass an emissions test.
A Straightforward Guide to Installation
Installing your new PCM is a job most DIYers can handle in their own driveway. For the 2004 GMC Safari, the module is located in the engine bay, on the driver’s side near the battery.
- Safety First: Disconnect the negative terminal from your vehicle’s battery and wait at least 10 minutes to allow the system to fully discharge.
- Locate the PCM: Find the module on the driver’s side of the engine compartment, typically mounted to a bracket near the battery.
- Disconnect the Wiring: Carefully unplug the electrical connectors from the old PCM. These connectors have locking tabs that need to be released before you can pull them out. Avoid forcing them.
- Remove the Old Module: Unbolt the old PCM from its mounting bracket. Keep the hardware, as you may need to reuse it.
- Install the New PCM: Mount your new, pre-programmed module onto the bracket and secure it with the bolts.
- Reconnect Everything: Plug the wiring harnesses firmly into the new PCM until they click into place. Reconnect the negative battery terminal.
- Final Step: Your vehicle may require a security relearn procedure, which can typically be done by cycling the key in the ignition. Consult your owner’s manual or a reliable online resource for the specific steps for your vehicle.
Verified Vehicle Compatibility
This module, part number 12586243 (also interchangeable with 89017739), is guaranteed to be a direct fit for the following vehicles. Please ensure your vehicle is on this list before ordering.
This Electronic Control Module is compatible with the 2004 GMC Safari (located on the LH front by the battery) and a wide range of other 2004-2005 GM vehicles, including but not limited to:
- ✔ 2004 Chevrolet Avalanche 2500, Blazer S10, Corvette, Express/Savana Vans, Silverado, Suburban, SSR, Trailblazer EXT
- ✔ 2004 GMC Envoy XL/XUV, Jimmy S15, Sierra, Sonoma, Yukon XL 2500
- ✔ 2004 Buick Rainier
- ✔ 2004 Chevrolet Astro
- ✔ 2004-2005 Cadillac CTS-V
- ✔ 2004 Pontiac GTO
Note: This is a partial list. This PCM fits dozens of GM applications. Providing your VIN ensures we send the correctly programmed module for your specific vehicle.
Frequently Asked Questions about the 2004 GMC Safari PCM
Frequently Asked Questions
Do I need to do anything after I install this PCM?
Because we program the module to your VIN before shipping, it is ready for installation. In some cases, a simple security or CASE relearn procedure may be necessary, which can often be done without special tools.
Is this part number 12586243 the same as 89017739?
Yes, these part numbers are interchangeable. Our module is a direct replacement for either of these original GM part numbers.
Where is the PCM located on my 2004 GMC Safari?
The PCM is located in the engine compartment on the driver’s side (LH), positioned near the battery on a mounting bracket.
Will this fix my Check Engine Light?
If the Check Engine Light is caused by an internal failure of the PCM (indicated by codes like P0601), then yes, this part will resolve the issue. It’s crucial to properly diagnose the problem before ordering.
How do I provide my VIN?
Simply enter your 17-digit Vehicle Identification Number (VIN) during the checkout process or send it to us in a message after your purchase. We cannot ship your order without it.