Restore Your Truck’s Performance and Reliability
Is your 1998 Chevrolet S10, GMC Sonoma, or another GM truck acting up? If you’re dealing with frustrating issues like a no-start condition, random stalling, a persistent Check Engine Light, or erratic shifting, a failing Powertrain Control Module (PCM) is often the culprit. As the brain of your vehicle, the PCM controls everything from fuel delivery and spark timing to transmission function. When it starts to fail, it can cause a cascade of problems that can sideline your trusty truck.
This isn’t just another part pulled from a shelf. This is a dependable, used OEM engine computer that we program specifically for your vehicle using your VIN. This critical step ensures that the module has the correct factory software and the latest GM updates for your truck’s specific configuration. By matching the programming to your VIN, we eliminate the guesswork and the need for an expensive trip to the dealership for flashing. You get a part that’s ready to install right out of the box, getting you back on the road faster.
A Technician’s Notebook: The Intermittent No-Start
I remember a 1998 GMC Jimmy with the 4.3L that came into my bay with an intermittent no-start that was driving the owner crazy. It would start fine for a week, then nothing. All the basics checked out—battery, starter, fuel pressure. The scanner wasn’t showing any hard codes, just a history of communication loss faults. After checking the main power and ground feeds to the PCM and finding them solid, I suspected the module itself was failing internally, especially when it got hot. We swapped in a VIN-programmed PCM like this one, and the problem vanished instantly. It’s a classic failure mode for these units, where internal solder joints crack over time, and this part is the direct, reliable fix.
Is Your Truck Showing These Signs of PCM Failure?
A faulty engine computer can manifest in many ways. If you’re experiencing any of the following, this module is likely the solution you need:
- ✔ Check Engine Light is illuminated with codes like P0601 (Internal Control Module Memory Check Sum Error), P0604, or P0606.
- ✔ The engine cranks but refuses to start.
- ✔ Vehicle stalls unexpectedly while driving or at idle.
- ✔ Noticeable decrease in fuel economy.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ Communication errors with your scan tool.
- ✔ Failure to pass an emissions inspection.
A Straightforward Guide to Your PCM Installation
Installing your programmed 1998 S10 Sonoma PCM is a job most DIYers can handle with basic tools. While the exact location can vary slightly by model, the process is generally the same.
- Safety First: Disconnect the negative terminal from your vehicle’s battery and secure it away from the post to prevent accidental reconnection.
- Locate the PCM: On most S10/S15/Sonoma/Blazer/Jimmy models, you’ll find the PCM in the engine bay, typically on the passenger side near the firewall or fender. On Express/Savana vans, it’s often in the rear of the engine compartment.
- Disconnect the Connectors: Carefully unclip the wiring harness connectors from the old PCM. There are usually multiple color-coded connectors with locking tabs. Do not force them.
- Remove the Old Module: Unbolt the old PCM from its mounting bracket. Keep the hardware as you will need it for the new unit.
- Install the New PCM: Mount your replacement PCM onto the bracket and securely re-fasten it.
- Reconnect Everything: Plug the wiring harnesses back into the correct ports on your new module. The connectors are keyed to only fit in the correct spot. Reconnect the negative battery terminal.
- Perform Security Relearn: After installation, you will likely need to perform a security relearn procedure (often called Passlock or Passkey). This simple procedure typically involves turning the key to the ‘ON’ position for 10-15 minutes, then ‘OFF’, and repeating two more times. This allows the new PCM to sync with your vehicle’s anti-theft system. Consult your owner’s manual for the exact procedure for your model. A Crankshaft Variation (CASE) relearn may also be required with a capable scan tool for optimal performance.
Verified Vehicle Compatibility
This PCM, identified by service number 16266645 or ID 09355699, is a direct replacement for a wide range of GM trucks and vans. It is compatible with the following part numbers: 09355699, 16266645, 9355699, 16250279, 16258815, 09366810, 9366810. Please verify your part number and check the list below to ensure a perfect fit for your vehicle.
CHEVROLET BLAZER S10 98 (RH front engine compartment), w/o build date opt ZN4; ID 9355699
OLDSMOBILE BRAVADA 98 (6-262, 4.3L), w/o build date opt ZN4; ID 9355699
CADILLAC ESCALADE 99 (LH front engine compartment), ID 9355699
GMC ENVOY 98 (RH front engine compartment), w/o build date opt ZN4; ID 9355699
CHEVROLET EXPRESS VANS 98-99 (Gasoline), ID 9355699
ISUZU HOMBRE 98 4.3L, w/o extended build date opt ZN4; ID 9355699
GMC JIMMY S15 98 (RH front engine compartment), w/o build date opt ZN4; ID 9355699
CHEVROLET & GMC PICKUP 1500/2500/3500 98-99 (Gasoline), ID 9355699
GMC SAFARI 98 (LH front by battery), ID 9355699
GMC SAVANA VANS 98-99 (Gasoline), ID 9355699
CHEVROLET S10 & GMC SONOMA 98 (4.3L), w/o build date opt ZN4; ID 9355699
CHEVROLET SUBURBAN 1500/2500 98-99 (Gasoline), ID 9355699
CHEVROLET TAHOE 98-99 (Gasoline), ID 9355699
GMC YUKON 98-99, ID 9355699
Frequently Asked Questions
Why do you need my VIN?
Your Vehicle Identification Number (VIN) is essential. We use it to load the exact, correct software from GM for your truck’s specific engine, transmission, and options. This ensures seamless communication between all modules and proper vehicle operation, just like the original.
Is this part difficult to install?
Not at all for most people with basic mechanical skills. It involves disconnecting the battery, unplugging a few connectors, and swapping the module. The most important post-installation step is the security relearn, which doesn’t require any special tools.
What is a security relearn procedure?
It’s a process that syncs the new PCM with your vehicle’s anti-theft system. Without it, the vehicle will not start. The procedure is simple and involves a sequence of key turns. We can provide general instructions, but it’s always best to check your vehicle’s specific procedure.
Is any other programming needed after installation?
Our programming handles the core operational software. However, for peak performance and to prevent certain codes, a Crankshaft Variation (CASE) relearn is recommended. This procedure requires a bi-directional scan tool and can be performed by most professional repair shops.
This is a used part. How can I be sure it’s reliable?
We source these modules from trusted salvage suppliers and each one is inspected before being programmed and shipped. By installing the latest GM software, we also ensure it’s operating on the most stable and efficient calibration available, often correcting issues present in older software versions. It’s a cost-effective and dependable solution.