Restore Peak Performance to Your GM Vehicle
Is your 2003 Express 3500 Van or another compatible GM vehicle suddenly running poorly, stalling, or showing a persistent Check Engine Light? You’re not just losing performance; you’re losing reliability. As the brain of your vehicle’s engine and transmission, a failing Powertrain Control Module (PCM) can cause a cascade of frustrating and hard-to-diagnose issues. This replacement PCM, part number 88864822, is the definitive solution to get your truck or van operating as it should, without the excessive cost and scheduling headaches of a dealership visit.
We take the guesswork out of the repair. Before this module ships, we will program it with the latest official GM software updates, specifically matched to your vehicle using the VIN you provide. This ensures that when it arrives, it’s ready for a straightforward installation, restoring factory communication between all critical systems for optimal fuel economy, emissions compliance, and engine power.
A Technician’s Notebook: The Intermittent Stall
I once had a 2003 Savana 2500 in my bay that was a fleet owner’s nightmare. The driver reported it would randomly stall at stoplights, but with no consistent codes—sometimes it would throw a communication error, other times nothing. We checked fuel pressure, sensors, and wiring harnesses, but everything tested fine. After days of diagnostics, we decided to monitor the PCM’s live data on a long test drive. We finally caught it: just before a stall, the PCM’s internal processor voltage would dip erratically. It was a classic case of a failing internal component inside the module. Swapping in a properly programmed PCM like this one solved the problem instantly. The fleet owner was relieved to have his reliable workhorse back on the road.
Is Your Vehicle Showing These Telltale Signs?
A faulty PCM can manifest in numerous ways. If you’re experiencing any of the following, this module is the likely solution:
- ✔ Persistent Check Engine Light (CEL) that won’t clear.
- ✔ Diagnostic Trouble Codes (DTCs) related to internal module failure, such as P0601, P0606, or U-series communication codes.
- ✔ Engine cranks but refuses to start (no-start condition).
- ✔ Unexplained drops in fuel economy.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ Engine stalling, stumbling, or misfiring for no apparent reason.
- ✔ Failure to pass state emissions testing.
A Straightforward Guide to Installation
Installing your new 2003 Express 3500 PCM is a manageable job for a DIYer with basic tools. Following these steps ensures a smooth process.
- Safety First: Always disconnect the negative terminal from your vehicle’s battery and wait at least 10 minutes to allow the system to fully discharge.
- Locate the Old PCM: On most Express/Savana vans, the PCM is located in the engine compartment on the driver’s side, near the firewall. On trucks and SUVs, it’s often under the battery tray on the driver’s side.
- Disconnect the Connectors: Carefully unplug the electrical harness connectors from the old module. They have locking tabs that may need to be lifted or slid to release. Inspect the connectors for any corrosion or damage.
- Remove the Old Module: Unbolt the old PCM from its mounting bracket. Keep the hardware as you will need it for the new module.
- Install the New PCM: Mount your new, pre-programmed PCM onto the bracket and secure it with the original hardware.
- Reconnect Everything: Firmly plug the harness connectors into the new module until they click into place. Reconnect the negative battery terminal.
- Perform Security Relearn: For many GM vehicles of this era, a security relearn procedure (often called a CASE learn) is required to sync the new PCM with your vehicle’s anti-theft system. This typically involves turning the key to the ‘ON’ position for 10-15 minutes, then off, and repeating two more times. Consult a service manual for your specific model’s procedure.
Verified Fitment For These GM Models
This module is a direct replacement for a wide range of 2003 and 2004 GM vehicles. Please verify your vehicle is on this list. This unit replaces service numbers including 12581565, 12570557, 12576106, 88864822, and 89017733.
ASTRO 03
BLAZER S10/JIMMY S15 03
CTS 04 (Base, ID 12581565)
CORVETTE 04 (ID 12581565)
EXPRESS/SAVANA 1500, 2500, 3500 VAN 03
S10/S15/SONOMA 03 (4.3L)
SAFARI (GMC) 03
SIERRA/SILVERADO 1500 PICKUP 03 (4.3L)
SIERRA/SILVERADO 2500 PICKUP 03 (Gasoline, 8.1L)
SIERRA/SILVERADO 3500 PICKUP 03 (Gasoline, 8.1L)
SUBURBAN 2500 03 (8.1L)
YUKON XL 2500 03 (8.1L)
Frequently Asked Questions About This PCM
How do I provide my VIN for programming?
After you complete your purchase, you will receive instructions to reply with your 17-digit Vehicle Identification Number (VIN). We cannot ship the module until we receive this information, as the programming is specific to your vehicle.
Is this a plug-and-play part?
Mostly, yes. Because we program it to your VIN, it eliminates the need for a dealership scan tool for software flashing. However, you will likely need to perform a security relearn procedure after installation, which can be done without special tools.
Will this fix my vehicle’s specific problem?
This PCM is a direct solution for failures within the module itself, which cause the symptoms listed above. While it solves a very common set of issues, you should always ensure that related components like sensors and wiring have been checked to confirm the PCM is the root cause.
Do I need to send my old PCM back?
No, there is no core charge or requirement to return your old module for this particular part.
What if my part number isn’t listed?
The primary part number is 88864822, but it’s also a compatible replacement for many other service numbers like 12581565, 12570557, and more. If your vehicle is on the fitment list, this module will work, even if the number on your old unit is different.