Is Your 2004 Blazer or Jimmy Running Rough? The PCM Might Be the Culprit.
If your trusty 2004 Chevrolet Blazer S10 or GMC Jimmy S15 is suddenly plagued by a persistent check engine light, erratic idling, poor fuel economy, or even a no-start condition, the problem may lie with its central nervous system: the Powertrain Control Module (PCM). This vital component, also known as the Engine Control Module (ECM), is responsible for managing everything from fuel injection and ignition timing to transmission shifting. When it fails, it can cause a cascade of frustrating and difficult-to-diagnose issues. This replacement PCM, part number 89017739, is the definitive solution to get your truck back on the road and running like new.
From the Diagnostic Bay
We once had a 2004 GMC Jimmy S15 come into the shop that had its owner chasing his tail for weeks. The truck had a rough idle and would occasionally stall at stoplights. The owner had already replaced the spark plugs, wires, and even the throttle position sensor, but the problem persisted. After connecting our scan tool, we noticed erratic data from multiple sensors, which didn’t make sense. Instead of throwing more parts at it, we focused on the common denominator—the PCM. A quick swap with a known-good module confirmed our suspicion. The original PCM had internal faults causing it to misinterpret sensor data. Installing a correctly programmed module fixed all the issues instantly, saving the customer from further unnecessary repairs and frustration.
Symptoms of a Failing 2004 Blazer S10 PCM
A failing engine computer can manifest in various ways. If you’re experiencing any of the following, it’s a strong indicator that your PCM needs attention:
- ✔ Persistent Check Engine Light (CEL) with various trouble codes.
- ✔ Engine stalling or cutting out unexpectedly.
- ✔ Rough or erratic idling.
- ✔ Noticeable decrease in fuel efficiency.
- ✔ Harsh or delayed automatic transmission shifts.
- ✔ The vehicle won’t start, even with a good battery and starter.
- ✔ Misfire codes that don’t resolve after replacing ignition components.
Plug-and-Play Solution with VIN Programming
The biggest hurdle when replacing a modern vehicle’s computer is programming. This isn’t just a simple swap. The PCM must be specifically coded to your vehicle’s unique Vehicle Identification Number (VIN) to communicate with other modules and to ensure it has the correct parameters for your engine and transmission. We take care of this complex step for you. Simply provide us with your VIN after purchase, and our technicians will flash this module with the latest, most stable GM software updates for your specific vehicle. It will arrive at your door ready for installation, eliminating the need for an expensive trip to the dealership.
Simple Installation Process
On the 2004 Blazer S10 and Jimmy S15, the PCM is conveniently located in the right-hand (passenger side) front of the engine compartment. Installation is straightforward for a DIY mechanic:
- Disconnect the Battery: Always disconnect the negative battery terminal before working on any electronic components.
- Locate the PCM: Find the module in the engine bay. It will have several large electrical connectors attached.
- Disconnect and Remove: Carefully unplug the wiring harness connectors. They have locking tabs that need to be released. Then, unbolt the module from its bracket.
- Install the New Module: Bolt the new, pre-programmed PCM into place and securely reconnect the wiring harnesses.
- Reconnect Battery: Reattach the negative battery terminal.
- Perform Security Relearn: In many cases, you will need to perform a simple security relearn procedure (often called a CASE relearn) to sync the new PCM with your vehicle’s anti-theft system. This can typically be done without special tools and instructions are widely available online.
This module, part number 89017739, also serves as a direct replacement for part number 12586243 and fits a wide array of 2004 GM trucks, vans, and SUVs, including the Corvette, Silverado, Sierra, Trailblazer, and Express Van. By ordering from us, you get a reliable, correctly programmed part that solves your vehicle’s issues without the dealership price tag.
Frequently Asked Questions
Do I need to get this PCM programmed?
No, we handle the programming for you before shipment. Just provide your vehicle’s VIN during or after checkout, and it will arrive ready to install with the latest GM software for your specific vehicle.
Where is the PCM located on my 2004 Blazer S10?
The Powertrain Control Module is located in the engine compartment, on the right-hand (passenger) side, near the front.
What is a CASE relearn procedure?
CASE stands for Crankshaft Angle Sensor Error. It’s a procedure that synchronizes the new PCM with the crankshaft position sensor. While not always required, it is often necessary to clear certain trouble codes and ensure optimal engine performance after a PCM replacement. This can often be done by a qualified mechanic with a high-end scan tool.
Will this fix my check engine light?
If the check engine light is caused by a faulty PCM, then yes, this part will resolve the issue. It’s crucial to have your vehicle properly diagnosed to ensure the PCM is the root cause of the problem and not a faulty sensor or wiring issue.
Is this compatible with other vehicles?
Yes, part number 89017739 is compatible with a very wide range of 2004 GM vehicles, including various Silverado, Sierra, Suburban, Yukon, and Express Van models. Please check the fitment list on this page to confirm compatibility with your specific vehicle.