Get Your GM Workhorse Back on the Job
Is your 1998-1999 Chevrolet Express 2500 Van running rough, shifting erratically, or refusing to start? A failing Powertrain Control Module (PCM) is often the culprit behind these frustrating and hard-to-diagnose issues. In my 20+ years of automotive diagnostics, I’ve seen countless good engines and transmissions get blamed when the real problem was the vehicle’s computer. This isn’t just a replacement part; it’s a direct solution to restore your van’s reliability and performance, getting you back to work or on the road without the dealership hassle and expense.
This is a reliable, tested OEM PCM, part number 9355699, sourced from a salvaged vehicle. The critical advantage here is our pre-shipment service: we program the module with the latest GM software updates specifically for your vehicle using the VIN you provide. This means it arrives ready for a straightforward installation, saving you hundreds in programming fees and a trip to the dealer. A properly functioning 1998-1999 Express 2500 PCM is essential for managing everything from fuel delivery and spark timing to transmission shift points and emissions control.
Case Study: A Tricky Diagnosis
I remember a 1999 Savana 3500 (which uses this same PCM) that came into the shop on a tow truck. It would crank but never start. The owner had already replaced the fuel pump and ignition coil. My scan tool showed no communication with the PCM. After checking the main power and ground wires to the computer—which were all good—it was clear the module itself had failed internally. We installed a VIN-programmed PCM just like this one, performed the security relearn, and the van fired up on the first try. It saved the customer from throwing more parts at a problem that was purely electronic.
Is Your Vehicle Showing These Symptoms?
- ✔ Check Engine Light is illuminated with codes like P0601 (Internal Memory Error) or P0606 (PCM Processor Fault).
- ✔ The engine cranks but won’t start.
- ✔ Rough idling, stalling, or poor engine performance.
- ✔ Noticeable decrease in fuel economy.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ Failure to pass an emissions or smog test.
- ✔ Intermittent issues that seem to have no other logical cause.
A Straightforward Guide to Installation
Replacing the 1998-1999 Express 2500 PCM is a job most DIYers can handle with basic tools. Since this unit comes programmed, you skip the most difficult step. Always follow proper safety procedures.
- Safety First: Disconnect the negative terminal from your vehicle’s battery to prevent any electrical shorts.
- Locate the PCM: On most Express/Savana vans, the PCM is located in the engine compartment on the driver’s side, near the battery or firewall. It’s a metal box with several large wiring harness connectors.
- Disconnect the Harnesses: Carefully unclip and remove all electrical connectors from the old PCM. Be gentle, as the plastic clips can become brittle over time.
- Remove the Old Module: Unbolt the PCM from its mounting bracket and remove it from the vehicle.
- Install the New Module: Bolt your new, pre-programmed PCM into the mounting bracket. Reconnect all wiring harnesses, ensuring they click securely into place.
- Reconnect the Battery: Reattach the negative battery terminal.
- Perform Security Relearn: This is a crucial final step for most GM vehicles of this era. You will need to perform the VATS/Passlock relearn procedure, which typically involves turning the key to the ‘ON’ position for 10-15 minutes, then off, and repeating this cycle three times. This allows the new PCM to synchronize with your vehicle’s anti-theft system. Consult your vehicle’s service manual for the exact procedure.
Verified Fitment for Your GM Truck, Van, or SUV
While this listing is focused on the 1998-1999 Express 2500 PCM, this module (service ID 9355699) is a direct replacement for a wide array of popular GM vehicles from that era. Please match your original part number to one of these: 09355699, 16266645, 16250279, 16258815, or 09366810. This part is compatible with many gasoline-powered Chevrolet, GMC, Cadillac, and Isuzu models, including:
- ✔ Full-Size Vans: Express & Savana 1500, 2500, 3500 (1998-1999)
- ✔ Full-Size Trucks: C/K 1500, 2500, 3500 Pickups (1998-1999)
- ✔ Full-Size SUVs: Tahoe, Yukon, Suburban, Escalade (1998-1999)
- ✔ Mid-Size Trucks/SUVs: S10, Sonoma, Blazer, Jimmy, Bravada, Envoy (1998)
- ✔ Astro/Safari Vans (1998)
Always verify your vehicle’s original part number before ordering to ensure perfect compatibility.
Do I need to do anything after I buy this PCM?
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 ship the module until we have this information, as we use it to program the PCM with the correct GM software for your specific vehicle configuration.
Is this a new part?
No, this is a genuine, tested OEM part that has been recovered from a salvaged vehicle. We inspect and verify its function before programming and shipping, offering a reliable and cost-effective alternative to a new dealership part.
Will I need a mechanic to install this?
Installation is straightforward for most people with basic mechanical skills. The key is performing the security relearn procedure after installation. If you are not comfortable with this step, a professional mechanic can complete the installation and relearn process for you.
What is the security relearn procedure?
It’s a process that syncs the new PCM with your vehicle’s anti-theft system (VATS or Passlock). Without it, the vehicle will not start. The standard procedure is a 30-minute cycle of turning the key on and off, but you should check the specific instructions for your model year.
Does this part come with a warranty?
Please refer to the warranty information provided in the listing details. We stand behind our tested and programmed modules to ensure you receive a functional, quality part.