Is Your 1998-1999 GM Truck or Van Running Rough?
If you’re dealing with a persistent check engine light, erratic transmission shifting, a no-start condition, or just poor engine performance in your GMC 1500, the Powertrain Control Module (PCM) is a very likely culprit. Over two decades in the shop, I’ve seen countless GMT400 and Express/Savana platform vehicles with baffling issues that all traced back to a failing PCM. The internal components, especially the drivers that control injectors and transmission solenoids, can degrade over time, leading to symptoms that often get misdiagnosed as bad sensors or mechanical failures.
Why Choose Our Programmed 1998-1999 GMC 1500 PCM?
This isn’t just a used part pulled from a yard. This is a complete, ready-to-install solution. We take a reliable, tested OEM computer and flash it with the latest official GM software updates, specifically matched to your vehicle’s VIN. This crucial step ensures that your truck’s engine and transmission operate exactly as the manufacturer intended, often resolving drivability issues that even the original software had. You get a dependable part without the high cost and hassle of a dealership visit for programming.
Expert Pro Tip from a 20-Year Technician
Before you install this new PCM, take 10 minutes to clean the main engine-to-chassis ground straps. On these GM trucks, they’re typically found near the front of the cylinder head or on the frame rail. A corroded or loose ground is the #1 killer of these modules. A wire brush and a quick tightening can prevent voltage spikes that damage the sensitive circuits inside the computer, ensuring your replacement part lasts for years to come.
Common Symptoms of a Failing GM PCM:
- โ Persistent Check Engine Light (CEL) with various codes
- โ Harsh or erratic automatic transmission shifting
- โ Engine cranks but will not start
- โ Stalling, stumbling, or poor fuel economy
- โ Communication errors with scan tools
- โ False sensor readings or multiple sensor codes at once
Simple, Straightforward Installation
Installing this module is a job most DIYers can handle in under 30 minutes with basic tools. Because we program it beforehand, you can skip the tow truck and the dealer’s service bay.
- Safety First: Disconnect the negative terminal from your truck’s battery.
- Locate the PCM: On most 1998-1999 GM trucks and full-size vans, the PCM is located in the engine compartment on the driver’s side, near the fender or firewall.
- Disconnect: Carefully unplug the electrical harness connectors. There are typically levers or tabs that need to be released.
- Remove Old Unit: Unbolt the mounting bracket holding the original PCM and remove it from the vehicle.
- Install New Unit: Mount your new, pre-programmed PCM in the same location, secure the bolts, and firmly reconnect the wiring harnesses until they click into place.
- Reconnect Battery: Re-attach the negative battery terminal.
- Perform Security Relearn: Your vehicle may require a simple 10-minute security relearn procedure to recognize the new PCM. Turn the key to the ‘ON’ position (don’t start) for 10 minutes, then turn it ‘OFF’ for 10 seconds. Repeat this two more times for a total of three cycles. Your truck should then start and run normally.
Guaranteed Compatibility
This PCM is a direct replacement for several part numbers. If your original module has any of the following numbers on its label, this unit is the correct fit for your vehicle: 09355699, 16266645, 9355699, 16250279, 16258815, 09366810, or 9366810. It is compatible with a wide range of 1998-1999 GM vehicles, including Chevrolet & GMC Pickups, Suburbans, Tahoes, Yukons, Express & Savana Vans, and more, as long as the ID matches 9355699. Please provide your VIN upon purchase so we can ensure perfect programming for your specific application.