Is Your 1998 GM Truck or SUV Acting Up?
If you’re dealing with frustrating, intermittent problems like stalling at stoplights, a hard or no-start condition, a persistent check engine light with baffling codes, or just poor engine performance, the culprit is often the vehicle’s brain: the Powertrain Control Module (PCM). For these late-90s GM vehicles, PCM failure is a common issue I’ve diagnosed hundreds of times in my 20+ years on the shop floor. The original internal components simply wear out over time, leading to a host of electronic gremlins that can be impossible to track down.
The Direct-Fit, Programmed Solution
This isn’t just a used part pulled from a salvage yard; it’s a complete solution. This is a reliable, tested PCM that we program specifically to your vehicle’s 17-digit Vehicle Identification Number (VIN) before we ship it. This critical step ensures the module has the correct software and calibrations for your engine, transmission, and factory options. We load the newest updates available from GM, often resolving issues the original software never could. This is the most reliable way to get your truck back to factory-spec operation without the high cost and hassle of a dealership visit.
From the Shop Floor: A Real-World Diagnosis
“A customer’s 1998 GMC Jimmy S15 came in last month on a tow truck. It would crank but not start, and the owner had already replaced the fuel pump and the crankshaft position sensor based on some forum advice. The scanner wouldn’t even communicate with the computer. Right away, that’s a huge red flag. Before diving deeper, we checked the power and ground feeds to the PCM connectorsโthey were perfect. This confirmed our suspicion: the PCM itself was dead internally. We installed one of our VIN-programmed modules, performed the quick security relearn, and it fired up on the first try. He’d spent over $400 chasing parts when the core problem was the computer all along.”
Common Symptoms of a Failing GM PCM:
- โ Check Engine Light is on with various communication or sensor codes (U-codes, P0601, etc.)
- โ Engine stalls randomly while driving or at idle
- โ Vehicle cranks but refuses to start
- โ Harsh or erratic automatic transmission shifting
- โ Noticeable drop in fuel economy
- โ Scanner tool cannot communicate with the PCM
Easy Installation for Your 1998 Blazer PCM
Replacing the module is a straightforward job you can do with basic hand tools. While the exact location varies slightly by model (check your service manual), the process is generally the same.
- Safety First: Always disconnect the negative terminal from your vehicle’s battery and wait 10-15 minutes for any residual power to drain.
- Locate the PCM: On a 1998 Blazer/Jimmy, it’s typically found in the engine bay on the passenger side fender wall. On vans and full-size trucks, it’s often on the driver’s side.
- Disconnect Connectors: Carefully unclip and remove the wiring harness connectors. Inspect them for any corrosion or bent pins. Clean them with electronics cleaner if necessary.
- Remove the Old Module: Unbolt the PCM from its mounting bracket and remove it from the vehicle.
- Install the New Module: Bolt your new, VIN-programmed PCM into place and securely reconnect the wiring harnesses. Ensure they click into place.
- Reconnect Battery: Reattach the negative battery terminal.
- Perform Security Relearn: You may need to perform a simple key-cycle security relearn procedure. Turn the key to the ‘ON’ position for 10-15 minutes, then ‘OFF’ for 10 seconds. Repeat this 2-3 times. This allows the new PCM to recognize your vehicle’s anti-theft system. Your truck should now start and run correctly.
This quality-tested used PCM, part number 16266645 (and interchangeable with service ID 09355699), is the definitive fix for a wide range of 1998-1999 GM trucks, vans, and SUVs. By providing your VIN, you guarantee you’re getting a module that’s ready to install right out of the box, saving you time, money, and diagnostic headaches.