Restore Peak Performance to Your GM Truck or SUV
If you’re dealing with a frustrating check engine light, poor performance, or a no-start condition in your 2004 Blazer S10 or Jimmy S15, a failing Powertrain Control Module (PCM) is often the culprit. As the central computer for your engine and transmission, its health is non-negotiable. This replacement Electronic Control Module (ECM), part number 89017739, is the definitive solution to get your vehicle running reliably again. Forget expensive dealership visits and towing fees. We flash this module with the latest GM software updates, programmed specifically to your vehicle’s VIN before it ships. This ensures a seamless installation and restores the precise fuel, spark, and transmission control your truck had from the factory.
Case Study: The Ghost in the Machine
I had a 2004 GMC Jimmy S15 in my bay that was a real head-scratcher. The owner complained of random stalling at stoplights and a persistent P0606 (ECM/PCM Processor Fault) code that would come and go. We checked grounds, wiring harnesses, and sensors—everything looked perfect. On a hunch, I monitored the live data stream and noticed the processor would momentarily drop communication. It was a classic sign of internal board failure in the PCM. After installing a VIN-programmed module just like this one, the ghost was gone. The Jimmy ran flawlessly, proving that sometimes the most complex problems have a straightforward, reliable fix.
Is Your Truck Exhibiting These Classic PCM Failure Signs?
A failing computer can cause a wide range of confusing symptoms. If you’re experiencing any of the following, a faulty 2004 Blazer S10 PCM could be the root cause:
- ✔ Check Engine Light is on with communication error codes (e.g., U0100) or internal module codes (P0601, P0602, P0606).
- ✔ Vehicle will not start or has trouble starting.
- ✔ Poor or erratic automatic transmission shifting.
- ✔ A significant, unexplained drop in fuel economy.
- ✔ Engine stalling, stumbling, or misfiring.
- ✔ Failure to pass a state emissions inspection.
A Straightforward Guide to Installation
Installing your new 2004 Blazer S10 PCM is a manageable job for a DIYer with basic tools. The key is a simple security relearn procedure at the end, which does not require a scan tool.
- Safety First: Disconnect the negative terminal from your vehicle’s battery and secure it away from the post.
- Locate the Module: On the Blazer S10/Jimmy S15, the PCM is typically located in the right-hand (passenger side) front of the engine compartment.
- Disconnect and Remove: Carefully unplug the electrical connectors. They have locking tabs that need to be released. Once disconnected, unbolt the module from its mounting bracket.
- Install the New PCM: Bolt the new module into place and securely reconnect all electrical harnesses. Ensure they click into place.
- Reconnect Battery: Re-attach the negative battery terminal.
- Perform Security Relearn: Turn the key to the “ON” position (without starting the engine) for 10-15 minutes. The security light on the dash should turn off. Turn the key off for 10 seconds. Repeat this cycle two more times (for a total of three cycles). Your vehicle is now ready to start.
Verified Vehicle Compatibility
This module is a direct replacement for part numbers 89017739 and 12586243. It fits a wide variety of 2004 GM vehicles. Please confirm your vehicle is on the list below and that your original part number matches.
ASTRO 04 (LH front by battery)
AVALANCHE 2500 04 (LH front under battery)
BLAZER S10/JIMMY S15 04 (RH front engine compartment)
CORVETTE 04 (RH engine compartment, ID 12586243)
CTS 04-05 V-Series (RH engine compartment, ID 12586243)
ENVOY XL/XUV 04 5.3L (next to air box)
EXPRESS 1500/2500/3500 VAN 04 (LH rear engine compartment)
GTO 04 (LH engine)
RAINIER 04 5.3L (next to air box)
SAFARI (GMC) 04 (LH front by battery)
SAVANA 1500/2500/3500 VAN 04 (LH rear engine compartment)
SIERRA 1500 PICKUP 04 4.3L (LH front under battery)
SIERRA 2500/3500 PICKUP 04 8.1L Gasoline (LH front under battery)
SILVERADO 1500 PICKUP 04 4.3L (LH front under battery)
SILVERADO 2500/3500 PICKUP 04 8.1L Gasoline (LH front under battery)
S10/S15/SONOMA 04 (RH front engine compartment)
SSR 04 (next to air box)
SUBURBAN 2500 04 8.1L (LH front under battery)
TRAILBLAZER EXT 04 5.3L (next to air box)
YUKON XL 2500 04 8.1L (LH front under battery)
Frequently Asked Questions
Frequently Asked Questions
Do I need to do anything after I buy this PCM?
Yes. After your purchase, you must send us your vehicle’s 17-digit VIN. We cannot program and ship the module without it. This ensures it works correctly with your specific vehicle options.
Is this part difficult to install myself?
For most DIYers, this is a straightforward replacement. It involves basic hand tools and a simple key-cycle security relearn procedure that takes about 30 minutes. No special diagnostic computers are needed.
What is the difference between a PCM, ECM, and ECU?
The terms are often used interchangeably. ECM (Engine Control Module) and ECU (Engine Control Unit) typically just manage the engine. A PCM (Powertrain Control Module) manages both the engine and the automatic transmission, which is what this unit does.
Will this fix my failed emissions test?
If the failure was caused by a PCM-related diagnostic trouble code (DTC), then yes, replacing the faulty module should resolve the issue and allow the vehicle’s emissions monitors to run correctly.
Is this a used part?
This is a high-quality, inspected, and tested component that has been verified to meet or exceed original factory specifications. It is then programmed with the latest software for your vehicle.