Programmed 1998-1999 Savana 3500 PCM 16266645 | VIN Matched & Ready to Install

Restore Your Van’s Core Performance and Reliability

Is your 1998 or 1999 GMC Savana 3500 van giving you headaches? Unexplained stalling, a persistent Check Engine Light, or rough, unpredictable engine behavior can bring your work or travels to a halt. As a technician with over two decades of experience, I’ve seen countless GM vehicles from this era sidelined by a failing Powertrain Control Module (PCM). This isn’t just a part; it’s the central computer for your engine and transmission. When it falters, everything falters. This reliable, tested PCM is the straightforward, cost-effective solution you need. It comes pre-programmed to your van’s specific Vehicle Identification Number (VIN), loaded with the latest GM software updates. This means you skip the expensive trip to the dealership for programming—it’s ready for installation right out of the box.

Common Signs of a Failing PCM

If you’re experiencing any of the following, a faulty PCM could be the culprit. A failing module can often mimic other component failures, making diagnosis tricky. Here are the classic symptoms I’ve seen in the bay:

• ✔ Your vehicle fails to start or starts intermittently.
• ✔ The engine stalls unexpectedly while driving or at idle.
• ✔ You notice a significant drop in fuel economy.
• ✔ The transmission shifts harshly, late, or erratically.
• ✔ The Check Engine Light is on, potentially with codes like P0601 (Internal Control Module Memory Check Sum Error) or P0605 (Internal Control Module ROM Error).
• ✔ Your scan tool cannot communicate with the computer.

A Straightforward Guide to Installation

Installing your replacement 1998-1999 Savana 3500 PCM is a manageable job for a confident DIYer or any professional mechanic. Following these steps will get you back on the road quickly.

1. Safety First: Always disconnect the negative terminal from your vehicle’s battery before starting any electrical work.
2. Locate the PCM: On most Savana and Express vans, the PCM is located in the engine compartment, on the driver’s side, near the air filter housing.
3. Disconnect the Wiring: Carefully unclip and remove the electrical harness connectors from the old PCM. The levers can be stiff, so be gentle but firm.
4. Remove the Old Module: Unbolt the PCM from its mounting bracket and remove it from the vehicle.
5. Install the New PCM: Mount your new, pre-programmed PCM onto the bracket and securely reconnect the wiring harnesses. Ensure they click into place.
6. Reconnect the Battery: Reattach the negative battery terminal.
7. Perform Security Relearn: You will likely need to perform a simple security relearn procedure. This typically involves turning the key to the ‘ON’ position for 10-15 minutes, then ‘OFF’, and repeating two more times. This allows the new PCM to sync with your vehicle’s anti-theft system.

Verified Vehicle Compatibility

This module is a direct replacement for service number 16266645 and other part numbers listed below. It is compatible with a wide range of GM trucks, vans, and SUVs from this era. Please verify your part number (often found on a sticker on your current module) or match your vehicle in the list below. This module fits vehicles with service ID 9355699.

Frequently Asked Questions about this PCM