Is Your GMC Truck Running Rough or Not Starting?
If you’re dealing with a persistent check engine light, erratic engine performance, or a no-start condition in your 1998 or 1999 GM truck, a failing Powertrain Control Module (PCM) is often the culprit. Over my 20+ years in the shop, I’ve seen countless GMT400 and later platform trucks sidelined by these exact issues. The PCM is the brain of your vehicle, and when it fails, it can cause a cascade of frustrating and hard-to-diagnose problems. This isn’t just an inconvenience; it’s a reliability issue that can leave you stranded.
The Direct Solution: A VIN-Programmed PCM
Forget expensive dealership diagnostics and programming fees. This is a reliable, tested, used OEM PCM that we program specifically for your vehicle before it ships. By providing us with your Vehicle Identification Number (VIN) at checkout, we flash the module with the latest official GM software updates for your exact make and model. This ensures that all factory parameters for fuel, spark, and transmission control are perfectly matched to your truck, restoring its original performance and efficiency.
Expert Pro Tip from a 20-Year Veteran Technician
Before you install your new PCM, take five minutes to inspect and clean the main wiring harness grounds. On these GM trucks, there’s typically a ground wire bolted directly to the engine block or cylinder head near the thermostat housing. Over time, this connection can corrode, creating resistance that mimics the symptoms of a bad PCM, like intermittent stalling or communication codes. A quick cleaning with a wire brush can prevent a misdiagnosis and ensure your new module functions perfectly from the start.
Common Symptoms of a Failing 1998-1999 GMC 1500 PCM
A faulty PCM can manifest in various ways. If your truck is experiencing any of the following, this module is the likely solution:
- ✔ Persistent Check Engine Light (CEL) with communication-related codes (U-codes) or random sensor codes.
- ✔ Engine cranks but refuses to start.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ Poor fuel economy and engine performance.
- ✔ Intermittent stalling or stumbling, especially after warming up.
- ✔ Failure to pass an emissions test due to monitor readiness issues.
Plug-and-Play Installation: No Dealer Visit Required
We handle all the complex programming so you can perform a simple, straightforward installation at home. This is a direct-fit replacement, designed to get you back on the road quickly.
- Safety First: Disconnect the negative terminal from your truck’s battery.
- Locate the PCM: On most 1998-1999 GM full-size trucks and vans, the PCM is located in the engine compartment on the driver’s side, near the fender or firewall.
- Disconnect Connectors: Carefully unclip the wiring harness connectors from the old module. Inspect the pins for any corrosion or damage.
- Swap the Module: Unbolt the old PCM from its bracket and set it aside. Mount your new, pre-programmed module in its place.
- Reconnect Everything: Securely plug the wiring harness connectors into the new PCM until they click. Reconnect the negative battery terminal.
- Final Check: Start the engine. The check engine light should be off, and the truck should run smoothly. A security relearn procedure may be necessary on some models, which typically involves cycling the key.
Guaranteed Compatibility
This module, part number 09366810, is a direct replacement for several other service numbers, including 09355699, 16266645, 16250279, and 16258815. It is compatible with a wide range of 1998-1999 General Motors vehicles, including the Chevrolet Silverado, Tahoe, Suburban, Express Van, and the GMC Sierra, Yukon, Savana Van, as well as the Cadillac Escalade and more. As long as your original module carries one of the compatible part numbers, this unit will work perfectly once programmed to your VIN.