Restore Your GM Truck’s Brainpower and Performance
As a technician with two decades of experience under the hood, I’ve seen firsthand the frustration a failing Powertrain Control Module (PCM) can cause. Your 1998 Chevy Blazer, GMC Jimmy, or other compatible GM truck is a workhorse, but when its central computer starts to fail, it can lead to a host of baffling problems—from random stalling and poor fuel mileage to a persistent Check Engine Light that won’t go away. This isn’t just an inconvenience; it’s a reliability issue that can leave you stranded. That’s where this fully programmed PCM, part number 09355699, comes in. It’s the reliable, straightforward solution to get your vehicle running right again.
This isn’t just a used part pulled from a yard. We take a quality, inspected PCM and flash it with the latest official GM software updates, specifically tailored to your vehicle’s Vehicle Identification Number (VIN). This critical step ensures that all the correct parameters for your engine, transmission, and emissions systems are loaded and ready to go. By providing us with your VIN at checkout, you receive a module that is truly plug-and-play, eliminating the need for an expensive trip to the dealership for programming. This is the smart, cost-effective fix for both seasoned mechanics and weekend DIYers looking to bring their truck back to factory-spec performance.
A Technician’s Notebook: The Intermittent No-Start Nightmare
I remember a 1998 GMC Sonoma that came into the shop with a classic head-scratcher: it would start perfectly for a week, then refuse to start for a day, with no rhyme or reason. The owner had already replaced the battery, starter, and fuel pump. After hooking up my scan tool, I noticed communication with the PCM was dropping out intermittently. On these older GM vehicles, heat soak and vibrations can cause microscopic cracks in the PCM’s internal solder joints. The result is a computer that works one minute and is a paperweight the next. We swapped in a VIN-programmed 1998 Blazer Jimmy PCM like this one. The new module restored stable communication, and the truck has been starting reliably ever since. It’s a textbook example of how a faulty computer can mimic other component failures.
Common Signs of a Failing PCM
- ✔ Check Engine Light is on with codes like P0601 (Internal Memory Error) or P0606 (PCM Processor Fault).
- ✔ The engine cranks but refuses to start.
- ✔ Unexplained stalling or rough idling.
- ✔ Noticeable decrease in fuel economy.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ Failure to pass an emissions or smog test.
- ✔ No communication with your OBD-II scan tool.
A Straightforward Guide to Installation
- ✔ Safety First: Disconnect the negative terminal from your vehicle’s battery and secure it away from the post.
- ✔ Locate the PCM: On most of these trucks and vans, the PCM is located in the engine bay, often on the driver’s or passenger’s side fender well or firewall. Refer to your vehicle’s service manual for the exact location.
- ✔ Disconnect Connectors: Carefully unplug the wiring harness connectors from the old PCM. There are typically release tabs that need to be pressed or lifted. Avoid pulling on the wires themselves.
- ✔ Remove the Old Module: Unbolt the old PCM from its mounting bracket. It’s usually held in by a few 10mm or 7mm bolts.
- ✔ Install the New Module: Mount your new, pre-programmed PCM onto the bracket and securely fasten the bolts.
- ✔ Reconnect and Secure: Plug the wiring harnesses firmly into the new module until they click into place. Reconnect your battery’s negative terminal.
- ✔ Perform Security Relearn (If Necessary): While this module is pre-programmed, some GM vehicles may require a simple security relearn procedure. This typically involves turning the key to the ‘ON’ position for 10-15 minutes. Consult your vehicle’s specific procedure if it doesn’t start immediately.
Verified Vehicle Compatibility
This module, identified by service number 09355699, is a direct replacement for a wide range of GM vehicles. It also interchanges with part numbers 16266645, 16250279, 16258815, and 09366810. Please match your original part number or verify fitment from the list below to ensure compatibility.
CHEVROLET 2500 PICKUP 98-99 (gasoline, LH engine compartment, ID 09355699)
CHEVROLET 3500 PICKUP 98-99 (gasoline, LH engine compartment, ID 09355699)
GMC 1500 PICKUP 98-99 (gasoline, LH engine compartment, ID 09355699)
GMC 2500 PICKUP 98-99 (gasoline, LH engine compartment, ID 09355699)
GMC 3500 PICKUP 98-99 (gasoline, LH engine compartment, ID 09355699)
ASTRO 98 (LH front by battery, ID 09355699)
SAFARI (GMC) 98 (LH front by battery, ID 09355699)
BLAZER S10/JIMMY S15 98 (RH front engine compartment, w/o build date opt ZN4, ID 09355699)
BRAVADA 98 (6-262, 4.3L, w/o build date opt ZN4, ID 09355699)
ENVOY 98 (RH front engine compartment, w/o build date opt ZN4, ID 09355699)
ISUZU HOMBRE 98 (4.3L, w/o extended build date opt ZN4, ID 09355699)
S10/S15/SONOMA 98 (6-262, 4.3L, w/o build date opt ZN4, ID 09355699)
EXPRESS/SAVANA 1500 VAN 98-99 (ID 09355699)
EXPRESS/SAVANA 2500 VAN 98-99 (gasoline, ID 09355699)
EXPRESS/SAVANA 3500 VAN 98-99 (gasoline, ID 09355699)
SUBURBAN 1500/2500 98-99 (gasoline, LH front engine compartment, ID 09355699)
TAHOE/YUKON 98-99 (gasoline, LH engine compartment, ID 09355699)
ESCALADE 99 (LH front engine compartment, ID 09355699)
Frequently Asked Questions
Why do you need my VIN?
Why do you need my VIN?
Your Vehicle Identification Number (VIN) allows us to program the PCM with the exact software and calibrations your specific vehicle requires. This includes engine size, transmission type, and emissions equipment, ensuring perfect compatibility and performance without needing a dealer visit.
Is this part difficult to install?
For most DIYers with basic hand tools, this is a straightforward job. The module is typically easy to access in the engine bay. Since we program it for you, the most complex part of the process is already done. Just swap the module and follow any vehicle-specific security relearn steps.
Will this fix my check engine light?
If the check engine light is caused by an internal PCM failure (like codes P0601-P0606), then yes, this will resolve the issue. However, if the light is on for another reason (e.g., a bad oxygen sensor), you will still need to fix that underlying problem.
What’s the difference between a PCM, ECM, and ECU?
The terms are often used interchangeably. ECU (Engine Control Unit) is a general term. ECM (Engine Control Module) typically just controls the engine. PCM (Powertrain Control Module) is the most common term for modern vehicles, as it controls both the engine and the transmission. For this vehicle, it is a PCM.
Does this part require additional programming?
No. The purchase price includes programming the module to your vehicle’s VIN with the latest GM software updates. It will arrive ready to install. In some cases, a simple security relearn procedure that you can do yourself may be required.