Get Your Truck Back on the Road with a Reliable, Programmed Engine Computer
Is your 1998 or 1999 GMC Yukon, Tahoe, or Chevy truck acting up? If you’re dealing with a frustrating no-start condition, erratic engine behavior, harsh shifting, or a persistent Check Engine Light, a failing Powertrain Control Module (PCM) is often the culprit. As a technician with over two decades of experience under the hood, I’ve seen how a faulty PCM can turn a dependable truck into a driveway ornament. This isn’t just a part; it’s the central command center for your engine and transmission, and when it fails, nothing works right.
We offer a straightforward, dependable solution. This is a thoroughly tested, used OEM PCM that we program specifically for your vehicle using your VIN. By flashing it with the latest GM software updates, we ensure it communicates perfectly with your truck’s systems right out of the box. You get a cost-effective repair without the exorbitant cost and hassle of a dealership visit for programming.
A Technician’s Notebook: The Phantom Misfire
A customer brought in his ’99 Suburban 1500 with a complaint that stumped two other shops. It had a random misfire that wouldn’t set a specific cylinder code, terrible fuel mileage, and would occasionally stall at red lights. They had replaced plugs, wires, the cap, and the rotor. On my scan tool, I saw erratic fuel trim data and a lazy response from the MAP sensor, even though the sensor itself tested fine. Experience told me to look at the source—the PCM. After swapping in a known-good, programmed module, the fuel trims stabilized instantly, and the engine smoothed out. The original PCM had failing internal processors that were corrupting sensor data, creating phantom issues. This is a classic failure I’ve seen dozens of times on these GMT400 platform trucks, and a correctly programmed PCM is the only real fix.
Is Your Truck Showing These Symptoms?
A failing PCM can cause a wide range of issues. If you’re experiencing any of the following, this module is likely the solution you need.
- âś” Check Engine Light is on with codes like P0601 (Internal Control Module Memory Check Sum Error) or P0605 (Internal Control Module Read Only Memory (ROM) Error).
- âś” The engine cranks but refuses to start.
- âś” Unexplained drops in fuel economy.
- âś” Harsh or erratic automatic transmission shifting.
- âś” The engine stalls, stumbles, or misfires for no apparent reason.
- âś” Communication errors with your OBD-II scan tool.
A Straightforward Guide to Your 1998-1999 Yukon PCM Installation
Replacing the PCM on these GM trucks is a job most DIYers can handle in their own driveway. Follow these simple steps to get your vehicle running smoothly again.
- 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 of these trucks and SUVs (like the Yukon, Tahoe, and pickups), the PCM is located in the engine bay, typically on the driver’s side inner fender or near the battery. In vans like the Express or Savana, it’s often in the LH rear of the engine compartment.
- Disconnect the Harnesses: The PCM has several large multi-pin electrical connectors. Carefully release the locking tabs or levers on each connector and pull them straight out from the module. Avoid wiggling them side-to-side, as this can damage the pins.
- Remove the Old Module: Unbolt the PCM from its mounting bracket. Keep the hardware, as you may need it to install the new unit.
- Install the New PCM: Mount your new, pre-programmed PCM onto the bracket and secure it. Reconnect the electrical harnesses, making sure they click securely into place and the locking levers are fully engaged.
- Reconnect the Battery: Reattach the negative battery terminal.
- Perform Security Relearn (If Necessary): While this PCM is programmed to your VIN, some vehicles may require a simple security relearn procedure. This typically involves turning the key to the ‘ON’ position for 10-15 minutes, then ‘OFF’, and repeating two more times. Your truck should then start normally.
Will This Fit My Truck or Van?
This engine computer is a direct replacement for a wide array of popular GM vehicles. We guarantee compatibility if your vehicle is listed below and your original module carries one of the specified part numbers. This module replaces part numbers: 09355699, 16266645, 9355699, 16250279, 16258815, 09366810, 9366810.
- 1998-1999 GMC Yukon & Chevy Tahoe (Gasoline Engines)
- 1999 Cadillac Escalade
- 1998-1999 Chevy & GMC 1500/2500/3500 Pickups (Gasoline Engines)
- 1998-1999 Chevy & GMC Suburban 1500/2500 (Gasoline Engines)
- 1998-1999 Chevy Express & GMC Savana 1500/2500/3500 Vans (Gasoline Engines)
- 1998 Chevy Astro & GMC Safari
- 1998 Oldsmobile Bravada, GMC Envoy, Chevy S10 Blazer, GMC S15 Jimmy (4.3L V6)
- 1998 Chevy S10, GMC Sonoma & Isuzu Hombre (4.3L V6)
Frequently Asked Questions
Do I need to do any programming myself?
No. We handle all the programming before we ship the module. We flash it with the latest GM software updates using the VIN you provide, so it arrives ready for installation.
How do I provide my VIN?
After you complete your purchase, you will receive instructions on how to send us your vehicle’s 17-digit VIN. We cannot ship your order until we receive this information.
Is this a new part?
No, this is a high-quality, tested used OEM (Original Equipment Manufacturer) part that has been sourced from a salvaged vehicle. This provides OEM reliability at a fraction of the cost of a new unit.
What if my original part number isn’t 16250279?
This module is a direct replacement for several part numbers, including 09355699, 16266645, and others listed in the description. As long as your vehicle is on the compatibility list, this module will function correctly.
Will this fix my transmission problems?
In many cases, yes. The PCM controls both the engine and the transmission. If the module is failing, it can cause poor shifting, incorrect gear selection, and other transmission-related symptoms. Replacing a faulty PCM often resolves these issues.
What is the security relearn procedure?
For most GM vehicles of this era, it’s a simple process: Turn the ignition key to the ON position (without starting the engine) for 10 minutes. The security light should turn off. Turn the key OFF for 5 seconds. Repeat this cycle two more times for a total of 3 cycles and 30 minutes. The vehicle should then start and run.