Is Your 1998-1999 GMC 3500 Running Rough? The PCM Might Be the Culprit.
If your trusty GMC 3500 is suddenly plagued by a check engine light, erratic shifting, poor fuel economy, or even a no-start condition, the problem may lie deep within its electronic heart: the Powertrain Control Module (PCM). As the central command center for your truck’s engine and transmission, a failing PCM can cause a wide range of frustrating and difficult-to-diagnose issues. This isn’t just an inconvenience; it affects your truck’s reliability, performance, and safety. Don’t let a faulty computer keep your workhorse off the road. We offer a direct, reliable solution.
From the Diagnostic Bay
We had a ’99 Chevy Suburban come in that had its owner chasing ghosts for weeks. The truck would randomly stall at stoplights, the transmission would shift hard between first and second, and the check engine light would come on with a random misfire code that moved from cylinder to cylinder. The owner had already replaced plugs, wires, the coil, and even the fuel filter. After hooking up our scanner and seeing erratic data from the crank and cam sensors that didn’t match the symptoms, we suspected the PCM. We swapped in a known-good, VIN-programmed module like this one, and the truck immediately ran like new. The old PCM had internal circuit failure, causing it to misinterpret sensor data. It’s a classic case where the problem isn’t the sensors, but the brain processing the information.
Common Symptoms of a Failing PCM
- ✔ Persistent Check Engine Light (CEL) on your dashboard.
- ✔ Engine stalling, stumbling, or misfiring for no apparent reason.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ A sudden, unexplained drop in fuel efficiency.
- ✔ The engine cranks but refuses to start.
- ✔ Failure to pass an emissions or smog test.
- ✔ Communication errors with diagnostic scan tools.
Your Direct Solution: The 1998-1999 GMC 3500 PCM
This is a genuine, quality-tested used Powertrain Control Module, service number 16266645, that serves as a direct replacement for a wide array of GM trucks and vans from that era. The key to our service is that we don’t just send you a part; we provide a fully programmed solution. Before shipping, our technicians will flash the module with the latest GM-certified software updates and program it specifically to your vehicle’s unique Vehicle Identification Number (VIN). This ensures that when you receive the part, it is ready to integrate seamlessly with your truck’s existing systems, restoring its original performance and operational parameters.
This plug-and-play approach eliminates the need for expensive dealership programming or specialized tools for the initial setup. While a simple “CASE relearn” (Crankshaft Angle Sensor Error) may be required after installation to sync the new computer with your engine’s crankshaft position sensor, this is a standard procedure that any competent mechanic can perform quickly.
By choosing this pre-programmed 1998-1999 GMC 3500 PCM, you are getting a cost-effective and reliable fix. Each unit is sourced from a salvaged vehicle and meticulously inspected to ensure it meets operational standards. It is compatible with a broad range of part numbers, including 09355699, 9355699, 16250279, 16258815, 09366810, and 9366810, making it a versatile solution for many popular GM models like the Chevrolet Silverado, Suburban, Tahoe, Express, GMC Sierra, Yukon, Savana, and more.
Frequently Asked Questions
Do I need to program this computer?
No. We handle all the programming for you before the part is shipped. You must provide us with your vehicle’s 17-digit VIN after purchase so we can load the correct software and vehicle-specific information onto the module.
What is a ‘CASE relearn’ and will I need to do one?
A CASE (Crankshaft Angle Sensor Error) relearn is a procedure that synchronizes the new PCM with your engine’s crankshaft position sensor. This is often necessary after replacing the PCM to prevent a P1336 trouble code. While the truck will typically run without it, completing the relearn ensures optimal performance and accuracy. Most automotive repair shops can perform this procedure in a few minutes with a capable scan tool.
Is this a new part?
This is a high-quality, tested, and fully functional used part that has been sourced from a salvaged vehicle. This allows us to provide a reliable and affordable solution for your repair needs.
How do I find my vehicle’s VIN?
Your 17-digit VIN can be found in several places: on a metal plate on the driver’s side of the dashboard (visible through the windshield), on the driver’s side door jamb sticker, and on your vehicle’s registration and insurance documents.
Will this fix my truck’s problem for sure?
This module will correct any issues directly caused by a faulty PCM. However, it is crucial that the vehicle has been properly diagnosed. This part will not fix problems related to other faulty components like sensors, wiring, or mechanical parts. We always recommend a thorough diagnosis by a qualified technician.
What other part numbers is this compatible with?
This PCM, 16266645, is a direct replacement for several other service numbers, including 09355699, 9355699, 16250279, 16258815, 09366810, and 9366810. Please check your original module to confirm compatibility.