Restore Peak Performance to Your GM Truck or Van
Is your trusty GMC or Chevy truck suffering from frustrating issues like intermittent stalling, poor fuel mileage, a persistent Check Engine Light, or erratic transmission shifting? Before you condemn the transmission or start replacing expensive sensors, the problem often lies with a failing Powertrain Control Module (PCM). This vital component is the brain of your vehicle, and when it falters, it can cause a cascade of confusing symptoms. This is a reliable, tested, and pre-programmed replacement PCM, part number 9355699, designed to get your vehicle running right again without a costly trip to the dealership.
We take the guesswork and hassle out of the repair. Unlike a generic part from a salvage yard that won’t work without special tools, this PCM is professionally flashed with the latest official GM software updates specifically for your vehicle. All we need is your Vehicle Identification Number (VIN) at checkout. This ensures that when the part arrives, it’s a true plug-and-play solution, ready to restore factory performance and communication between your engine and transmission.
A Technician’s Notebook: The Misleading Misfire
I once had a 1999 Chevy Suburban in my bay with what seemed like a classic random misfire. The owner had already replaced plugs, wires, the cap, and the rotor. The scan tool showed a P0300 code, but no specific cylinder was at fault. After hours of chasing my tail checking fuel pressure and injectors, I decided to look at the PCM’s behavior on a scope. I noticed the injector driver signals were weak and erratic. A failing capacitor inside the original PCM was causing it to randomly cut fuel to different cylinders, mimicking a fuel or ignition problem. We installed a VIN-programmed PCM just like this one, and the truck ran perfectly. It’s a powerful reminder that the computer itself is often the root cause of the most baffling issues.
Is Your GM Vehicle Showing These Signs?
A failing PCM can manifest in many ways. If you’re experiencing any of the following, this module is the likely solution for your 1998-1999 GMC 1500 PCM or other compatible vehicle.
- âś” Check Engine Light is on with codes like P0601 (Internal Control Module Memory Check Sum Error) or P0606 (PCM Processor Fault).
- âś” The engine cranks but refuses to start.
- âś” Unexplained stalling or rough idling, especially after warming up.
- âś” Noticeable decrease in fuel economy.
- âś” Harsh or delayed transmission shifting.
- âś” Failure to pass an emissions inspection.
- âś” Communication errors with your scan tool.
A Straightforward Guide to PCM Installation
Replacing the PCM on these GM trucks and vans is a job most DIYers can handle in under 30 minutes with basic hand tools. Follow these steps for a successful installation.
- Safety First: Always disconnect the negative terminal from your vehicle’s battery and secure it away from the post to prevent any accidental power surges.
- Locate the PCM: On most trucks and SUVs like the Tahoe, Suburban, and pickups, the PCM is located in the engine bay on the driver’s side, near the fender or firewall. On vans like the Express and Savana, it’s often in the rear of the engine compartment.
- Disconnect the Connectors: Carefully unclip and remove all wiring harness connectors from the old PCM. These connectors are color-coded, making reinstallation simple. Avoid forcing them.
- Remove the Old Module: Unbolt the old PCM from its mounting bracket. It’s typically held in by two or three bolts.
- Install the New PCM: Mount your new, pre-programmed PCM onto the bracket and secure it with the bolts. Reconnect the wiring harnesses, ensuring each one clicks firmly into place.
- Reconnect the Battery: Reattach the negative battery terminal.
- Perform Security Relearn: You will likely need to perform a simple security relearn procedure. Turn the key to the ‘ON’ position for 10-15 minutes, then ‘OFF’ for 10 seconds. Repeat this cycle 3 times. On the fourth try, the vehicle should start, completing the process.
Verified Compatibility for Your GM Vehicle
This engine computer, identified by part number 9355699, is a direct replacement for a wide range of popular GM vehicles from the late 1990s. It is compatible with the original part numbers 09355699, 16266645, 16250279, 16258815, 09366810, and 9366810. Please verify your original part number or use the fitment list below. This module fits many gasoline-powered models including:
- âś” 1998-1999 Chevrolet & GMC 1500/2500/3500 Pickups
- âś” 1998-1999 Chevrolet Tahoe & GMC Yukon
- âś” 1998-1999 Chevrolet & GMC Suburban
- âś” 1999 Cadillac Escalade
- âś” 1998-1999 Chevrolet Express & GMC Savana Vans (1500/2500/3500)
- âś” 1998 Chevrolet Astro & GMC Safari Vans
- âś” 1998 S10/S15/Sonoma, Blazer/Jimmy, Bravada, Envoy, & Isuzu Hombre (4.3L V6 models)
Frequently Asked Questions
Frequently Asked Questions
Do I need to do any programming myself?
No. We handle all the programming before we ship the module. You just need to provide your vehicle’s 17-digit VIN when you place your order. It arrives ready for installation.
Is this a new part?
No, this is a thoroughly tested, used OEM part sourced from a salvaged vehicle. This allows us to provide a reliable and affordable solution for vehicles that may no longer have new parts available.
What is the security relearn procedure?
It’s a simple process that syncs the new PCM with your vehicle’s anti-theft system. It involves cycling the ignition key and typically takes about 30 minutes. Instructions are included above.
How do I find my original part number?
The part number is printed on a sticker on your original PCM. You can cross-reference it with the compatible numbers listed on this page to ensure a perfect match.
Will this fix my transmission shifting problems?
In many cases, yes. The PCM controls transmission line pressure and shift points. If the PCM is faulty, it can cause poor shifting performance. Replacing it often resolves these issues.