Restore Your Truck’s Brain and Get Back on the Road
Is your trusty 1998 Chevy S10, GMC Sonoma, or another GM truck acting up? If you’re dealing with frustrating issues like a no-start condition, erratic shifting, a persistent Check Engine Light, or abysmal fuel economy, the problem often points directly to a failing Powertrain Control Module (PCM). As the central computer of your vehicle, when the PCM starts to fail, it can cause a cascade of problems that can be difficult to diagnose. This is a reliable, tested, and pre-programmed replacement PCM, service number 09355699, designed to get your vehicle running smoothly again without the exorbitant cost and hassle of a dealership visit.
Case Study: A Tricky Diagnosis
A customer brought in a ’98 GMC Jimmy with the 4.3L V6 that had intermittent stalling and a random P0300 (Random/Multiple Cylinder Misfire) code that no amount of tune-up parts would fix. We checked fuel pressure, spark, and injectors—all were fine. After connecting a scope, we noticed the injector pulse width was erratic under load. This pointed away from the mechanical parts and straight to the driver circuits inside the PCM. After swapping in a correctly programmed PCM like this one, the misfire vanished and the truck ran perfectly. It’s a classic example of how a failing computer can mimic a mechanical problem, costing you time and money on unnecessary parts.
Is Your Vehicle Showing These Symptoms?
A failing PCM can manifest in many ways. If you’re experiencing any of the following, this module is the likely solution for your 1998 S10 Sonoma PCM issues:
- ✔ Check Engine Light is on with codes like P0601, P0604, or P0605 (Internal Module Errors).
- ✔ Vehicle will not start or is very difficult to start.
- ✔ Rough or unstable idling.
- ✔ Poor acceleration and overall engine performance.
- ✔ Automatic transmission shifts harshly, late, or not at all.
- ✔ Unexplained drop in fuel mileage.
- ✔ Communication errors with diagnostic scan tools.
A Straightforward Guide to Installation
Installing your replacement PCM is a manageable job for a DIYer with basic tools. While the exact location varies slightly by model (see fitment list), the process is generally the same. Getting your 1998 S10 Sonoma PCM installed is a breeze.
- Safety First: Disconnect the negative terminal from your vehicle’s battery to prevent any electrical shorts.
- Locate the PCM: On most of these trucks and vans, it’s located in the engine compartment, often on the driver’s or passenger’s side fender well or near the battery.
- Disconnect Connectors: Carefully unclip the wiring harness connectors from the old PCM. These connectors have locking tabs; be gentle to avoid breaking them.
- Remove the Old Module: Unbolt the old PCM from its mounting bracket and remove it from the vehicle.
- Install the New Module: Bolt your replacement PCM into the mounting bracket and securely reconnect the wiring harnesses. Ensure they click into place.
- Reconnect Battery: Reattach the negative battery terminal.
- Perform Security Relearn: You will likely need to perform a simple security relearn procedure. This typically involves turning the key to the ‘ON’ position for 10-15 minutes, then ‘OFF’ for 10 seconds, and repeating this cycle three times. This allows the vehicle’s anti-theft system to recognize the new PCM.
Verified Vehicle Compatibility
This PCM, identified by service number 09355699, is a direct-fit replacement for a wide range of GM vehicles. It is also interchangeable with part numbers 16266645, 16250279, 16258815, and 09366810. Please match your part number or verify your vehicle is on the list below to ensure proper fitment.
BLAZER S10/JIMMY S15 98 (RH front engine compartment), w/o build date opt ZN4
BRAVADA 98 (6-262, 4.3L), w/o build date opt ZN4
CHEVROLET 1500 PICKUP 98-99 (Gasoline, LH front engine compartment)
CHEVROLET 2500 PICKUP 98-99 (Gasoline, LH front engine compartment)
CHEVROLET 3500 PICKUP 98-99 (Gasoline, LH front engine compartment)
ENVOY 98 (RH front engine compartment), w/o build date opt ZN4
ESCALADE 99 (LH front engine compartment)
EXPRESS 1500 VAN 98-99
EXPRESS 2500 VAN 98-99 (Gasoline)
EXPRESS 3500 VAN 98-99 (Gasoline)
GMC 1500 PICKUP 98-99 (Gasoline, LH engine compartment)
GMC 2500 PICKUP 98-99 (Gasoline, LH engine compartment)
GMC 3500 PICKUP 98-99 (Gasoline, LH engine compartment)
ISUZU HOMBRE 98 (4.3L), w/o extended build date opt ZN4
S10/S15/SONOMA 98 (6-262, 4.3L), w/o build date opt ZN4
SAFARI (GMC) 98 (LH front by battery)
SAVANA 1500 VAN 98-99
SAVANA 2500 VAN 98-99 (Gasoline)
SAVANA 3500 VAN 98-99 (Gasoline)
SUBURBAN 1500 98-99 (Gasoline, LH front engine compartment)
SUBURBAN 2500 98-99 (Gasoline, LH front engine compartment)
TAHOE 98-99 (Gasoline, LH front engine compartment)
YUKON 98-99 (LH engine compartment)