Is Your Late 90s GM Truck or Van Running Rough?
If you’re dealing with frustrating issues like a persistent check engine light, erratic shifting, a no-start condition, or poor fuel economy in your 1998-1999 Chevrolet, GMC, Cadillac, or Isuzu vehicle, the culprit is often a failing Powertrain Control Module (PCM). As the central computer, the PCM is responsible for managing everything from fuel injection and ignition timing to transmission shift points and emissions controls. When it starts to fail, it can cause a cascade of problems that are often misdiagnosed, leading to costly and unnecessary repairs.
This genuine OEM PCM, part number 09355699, is the definitive solution to restore your vehicle’s performance, reliability, and drivability. Unlike a generic part from a local auto store or a pull from a junkyard with unknown history, this unit is professionally tested and programmed specifically for your vehicle. We take your Vehicle Identification Number (VIN) and flash the module with the latest GM-certified software updates. This ensures perfect communication between all vehicle systems and accounts for any factory improvements made since your truck first rolled off the assembly line.
From the Diagnostic Bay
I once had a 1999 Suburban 1500 come in with a complaint of harsh, delayed shifting and a flashing check engine light. The owner had already spent a small fortune replacing the transmission solenoids and fluid based on another shop’s recommendation, but the problem persisted. After hooking up my scan tool, I noticed erratic data from the PCM and communication dropouts. We swapped in a VIN-programmed PCM, performed the security relearn, and the truck shifted like it was brand new. The issue was never mechanical; it was the computer failing to properly command the transmission. This is a classic case where a faulty 1998-1999 GM PCM mimics a major transmission failure.
Symptoms of a Failing 1998-1999 GM PCM
- ✔ Persistent Check Engine Light (CEL) with various communication or sensor codes.
- ✔ Harsh, erratic, or delayed automatic transmission shifting.
- ✔ Engine stalling, stumbling, or misfiring for no apparent reason.
- ✔ Complete no-start condition where the engine cranks but won’t fire up.
- ✔ Noticeable decrease in fuel economy.
- ✔ Failure to pass state emissions testing.
- ✔ Inconsistent or non-functional dashboard gauges.
- ✔ Security light staying on, preventing the vehicle from starting.
The Plug-and-Play Advantage
The biggest hurdle when replacing an engine computer is the programming. An unprogrammed module simply will not work. It lacks the specific instructions for your vehicle’s engine size, transmission type, and options. Our service eliminates this problem entirely. By providing your VIN during checkout, you receive a module that is ready for installation. In most cases, the only additional step is a simple security relearn procedure that you can do yourself in about 15 minutes, with no special tools required. We provide clear instructions to make the process seamless.
This PCM is a direct replacement for a wide range of popular GM trucks and vans from the era, including the Chevrolet 1500/2500/3500 Pickups, Tahoe, Suburban, Express Van, as well as the GMC Sierra, Yukon, Savana, and even the Cadillac Escalade. It serves as a direct cross-reference for multiple part numbers, including 16266645, 9355699, 16250279, 16258815, and 09366810, ensuring broad compatibility.
Frequently Asked Questions
How does the VIN programming process work?
After you place your order, you will need to provide us with your vehicle’s 17-digit VIN. Our technicians use this number to access the official GM database and load the exact software calibration for your specific make, model, engine, and options. This ensures the PCM works perfectly right out of the box.
Do I need to do anything after I install this PCM?
Yes, you will likely need to perform a security relearn procedure, also known as a Passlock or Passkey relearn. This syncs the new PCM with your vehicle’s anti-theft system. It’s a simple process that typically involves turning the key to the ‘ON’ position for 10-15 minutes, then off, and repeating two more times. We include instructions for this procedure.
Is this a new computer?
This is a high-quality, used OEM computer sourced from a salvaged vehicle. Each unit is thoroughly inspected, cleaned, and tested to ensure it is fully functional before being programmed and shipped. This provides OEM reliability without the high cost of a new-old-stock part.
Will this fix my transmission shifting problems?
In many cases, yes. The PCM directly controls the electronic solenoids inside the transmission. A failing PCM is a very common cause of shifting issues like harsh shifts, slipping, or getting stuck in one gear on these GM vehicles. While it’s not a guaranteed fix for every transmission problem, it should be considered a primary suspect if the transmission’s mechanical components are known to be in good condition.
Where is the PCM located on my vehicle?
On most of the trucks and SUVs like the Silverado, Sierra, Tahoe, and Suburban, the PCM is located in the engine compartment on the driver’s side, near the fender or firewall. On vans like the Express and Savana, it is typically found in the LH rear engine compartment. Always disconnect the battery before attempting to remove or install the module.