Restore Peak Performance to Your GM Vehicle
Is your work van or truck suddenly running rough, stalling, or refusing to start? As a mechanic with over two decades of experience under the hood, I’ve seen how a faulty Powertrain Control Module (PCM) can cause some of the most frustrating and hard-to-diagnose issues. It’s the brain of your vehicle, and when it starts to fail, it can mimic a dozen other problems. This isn’t just an inconvenience; it’s a hit to your productivity and peace of mind. You need a reliable fix, and you need it now.
This Powertrain Control Module, part number 88864822, is the definitive solution for a wide range of 2003-2004 GM vehicles. The best part? We handle the complex part for you. Before this module ever leaves our facility, we flash it with the latest official GM software, programmed specifically to your vehicle’s VIN. This eliminates the need for an expensive trip to the dealership for programming, making this a straightforward repair for a professional technician or a confident DIYer.
From the Diagnostic Bay: The Ghost in the Machine
I remember a 2003 Silverado with the 8.1L that came into my shop. The owner had already replaced the throttle body, mass air flow sensor, and a few coil packs chasing an intermittent stalling problem and a P0606 (PCM Processor Fault) code that would come and go. He was at his wit’s end. We hooked up our professional scan tool and monitored the live data streams. Everything looked normal… until it didn’t. For a split second, the fuel trim and ignition timing data would go haywire right before it stalled. This wasn’t a sensor issue; it was the computer itself making bad decisions. We installed a VIN-programmed PCM like this one, performed the security relearn, and the truck ran perfectly. It’s a classic case where the core problem was the processor, not the parts it was controlling.
Is Your Vehicle Showing These Symptoms?
- ✔ Check Engine Light is illuminated with codes like P0601, P0602, or P0606.
- ✔ The engine cranks but refuses to start.
- ✔ Unexplained stalling or rough idling, especially when warm.
- ✔ A noticeable decrease in fuel economy.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ Communication errors with your scan tool (U-codes).
- ✔ Failure to pass an emissions or smog test.
A Straightforward Guide to Installation
- ✔ Safety First: Disconnect the negative terminal from your vehicle’s battery and secure it away from the post to prevent accidental contact.
- ✔ Locate the PCM: On most GM vans and trucks from this era, the PCM is located in the engine compartment. On Savana/Express vans, it’s on the driver’s side rear of the engine bay. On trucks, it’s often under the battery tray on the driver’s side.
- ✔ Disconnect the Harnesses: Carefully unclip and disconnect the large electrical wiring harnesses from the old PCM. These connectors have locking tabs that must be released before pulling.
- ✔ Remove the Old Module: Unbolt the PCM from its mounting bracket. Keep the hardware, as you may need to reuse it.
- ✔ Install the New PCM: Mount your new, pre-programmed PCM onto the bracket and securely fasten it.
- ✔ Reconnect Everything: Firmly plug the wiring harnesses back into the new module until they click into place. Reconnect your vehicle’s negative battery terminal.
- ✔ Perform Security Relearn: You will likely need to perform a simple security relearn procedure (often called a Passlock or VATS relearn). This typically involves turning the key to the ‘ON’ position for 10-15 minutes, then off, and repeating two more times. Your vehicle’s service manual will have the exact procedure.
Verified Vehicle Compatibility
This module is a direct replacement for service number 88864822 and is compatible with a wide array of GM models. Please verify your vehicle is on this list to ensure proper fitment. This part fits the following vehicles with the specified options:
ASTRO 03 (LH front by battery)
BLAZER S10/JIMMY S15 03 (RH front engine compartment)
CTS 04 Base, (RH engine compartment), ID 12581565
CORVETTE 04 (RH engine compartment), ID 12581565
EXPRESS 1500 VAN 03 (LH rear engine compartment)
EXPRESS 2500 VAN 03 (LH rear engine compartment)
EXPRESS 3500 VAN 03 (LH rear engine compartment)
S10/S15/SONOMA 03 4.3L, (RH front engine compartment)
SAFARI (GMC) 03 (LH front by battery)
SAVANA 1500 VAN 03 (LH rear engine compartment)
SAVANA 2500 VAN 03 (LH rear engine compartment)
SAVANA 3500 VAN 03 (LH rear engine compartment)
SIERRA 1500 PICKUP 03 4.3L, (LH front under battery)
SIERRA 2500 PICKUP 03 8.1L Gasoline, (LH front under battery)
SIERRA 3500 PICKUP 03 8.1L Gasoline, (LH front under battery)
SILVERADO 2500 PICKUP 03 8.1L Gasoline, (LH front under battery)
SILVERADO 3500 PICKUP 03 8.1L Gasoline, (LH front under battery)
SUBURBAN 2500 03 8.1L, (LH front under battery)
YUKON XL 2500 03 8.1L, (LH front under battery)
Frequently Asked Questions
Do I need to send you my old PCM?
Do I need to send you my old PCM?
No, there is no core charge or requirement to return your old part. You can recycle your old module locally.
How do I provide my VIN?
After you complete your purchase, you will receive instructions on how to send us your 17-digit Vehicle Identification Number (VIN). We must have your VIN to program the module correctly before shipping.
Is this part truly plug-and-play?
This module is pre-programmed, which handles the most difficult step. However, on most GM vehicles, you will need to perform a simple, no-tool ‘Security Relearn Procedure’ to sync the new PCM with your vehicle’s anti-theft system. This process is outlined in our installation guide and takes about 30 minutes.
Will this fix my specific problem?
This PCM is a direct solution for failures within the module itself, which cause a wide range of symptoms. While it resolves many common issues, it’s crucial to ensure your vehicle has been properly diagnosed. This part will not fix problems caused by faulty wiring, sensors, or other mechanical components.
What if I have the wrong service number?
This module replaces a long list of original service numbers, including 12581565, 12570557, 89017733, and more. As long as your vehicle model and year are on our compatibility list, this module will function correctly once programmed to your VIN.