Restore Peak Performance to Your GMC Truck
Is your 1998 or 1999 GMC 3500 Pickup suffering from baffling electrical issues, poor engine performance, or erratic transmission shifting? The heart of your truck’s operational command, the Powertrain Control Module (PCM), is often the source of these frustrating problems. This vital component acts as the central computer, managing everything from fuel injection and ignition timing to transmission shift points and emissions controls. When it begins to fail, the symptoms can be widespread and difficult to diagnose. This replacement PCM, part number 09355699, is the definitive solution to get your reliable workhorse back on the road and running like it should.
From the Diagnostic Bay
I once had a ’99 Chevy Suburban come in with a complaint of a harsh 1-2 shift and intermittent stalling at stoplights. The owner had already replaced the throttle position sensor and the mass airflow sensor, but the problem persisted. After hooking up the scan tool, I noticed the data stream from the PCM was erratic, with fuel trim values jumping all over the place. Instead of continuing to chase sensors, we inspected the PCM. We found subtle signs of internal corrosion on the board. A replacement, pre-programmed PCM like this one solved all the issues instantly. It’s a classic case where the ‘brain’ was the problem, not the ‘senses’.
Common Symptoms of a Failing PCM
If you’re experiencing any of the following issues, a faulty engine computer could be the culprit. This replacement 1998-1999 GMC 3500 PCM is designed to correct these problems and restore your vehicle’s factory performance.
- ✔ Persistent Check Engine Light (CEL) that won’t clear or returns with various codes.
- ✔ Engine stalling, stumbling, or hesitating during acceleration.
- ✔ Rough or inconsistent idling.
- ✔ Noticeable decrease in fuel economy.
- ✔ Harsh or delayed automatic transmission shifting.
- ✔ Complete no-start condition where the engine cranks but won’t fire up.
- ✔ Failure to communicate with diagnostic scan tools.
The Plug-and-Play Solution for Your 1998-1999 GMC 3500 PCM
Don’t let a faulty computer keep your truck sidelined. We make the replacement process straightforward. Unlike a generic module from a parts store, this unit is specifically programmed for your vehicle before it ever leaves our facility. Simply provide us with your truck’s Vehicle Identification Number (VIN) during checkout, and our technicians will flash the module with the latest, most stable software updates from General Motors. This ensures perfect compatibility with your engine, transmission, and all factory options, eliminating the need for an expensive trip to the dealership for programming.
This module is a direct replacement for part numbers 09355699, 16250279, and 09366810. It also fits a wide range of other GM trucks, vans, and SUVs from this era, including the Chevrolet 3500, Tahoe, Suburban, Express, GMC Yukon, Savana, and more. Please verify the part number or consult the detailed fitment list to ensure compatibility.
Frequently Asked Questions
What exactly does the Powertrain Control Module (PCM) do?
The PCM is your vehicle’s main computer. It takes data from sensors all over the engine and transmission to control fuel delivery, spark timing, transmission shifting, and emissions systems for optimal performance and efficiency.
Do I need to program this module?
No. We handle the programming for you. You must provide your vehicle’s VIN when you order, and we will flash the module with the correct GM software for your specific truck. This makes installation much simpler.
Is any other procedure required after I install the PCM?
Yes, you will likely need to perform a security relearn procedure, also known as a Passlock or VATS relearn. This syncs the new PCM with your vehicle’s anti-theft system. It’s a simple procedure that typically involves turning the key to the ‘ON’ position for 10-15 minutes, then off, and repeating two more times. Instructions are readily available online for your specific model.
How can I be sure my old PCM is the problem?
While the symptoms listed are strong indicators, it’s always best to have a qualified mechanic perform a full diagnostic. They can rule out issues with wiring, sensors, or grounds before you replace the PCM. However, if multiple unrelated codes are present or the module fails to communicate, the PCM is the most likely cause.
Where is the PCM located on my 1998-1999 GMC 3500?
On most of these GM trucks, the PCM is located in the engine compartment on the driver’s side, often near the battery or on the inner fender. It’s a silver metal box with multiple large wiring harness connectors.