Is Your 1998 Chevy Astro or GMC Safari Running Rough?
If you’re dealing with frustrating engine problems like stalling, poor fuel economy, a persistent check engine light, or a no-start condition, the brain of your vehicle’s engine management system—the Powertrain Control Module (PCM)—may be the culprit. For many 1998-1999 GM trucks and vans, these issues point directly to a failing computer. This isn’t just an inconvenience; it’s a critical failure that can leave you stranded. Instead of paying dealership prices for a new module and programming, get back on the road with our reliable, VIN-programmed solution.
This is a genuine, used GM engine computer, service number 9366810, which has been carefully tested to ensure full functionality. The real value is in our service: we flash the module with the latest official GM software updates and program it specifically to your vehicle’s Vehicle Identification Number (VIN). This means it arrives at your door ready for a straightforward installation, restoring the precise fuel delivery, ignition timing, and transmission shifting your vehicle had when it was new.
From the Diagnostic Bay
We had a 1998 GMC Safari come into the shop that was a real head-scratcher for the owner. He’d replaced the fuel pump, spark plugs, and even the distributor, chasing an intermittent stalling problem that left no codes. The van would run fine for days, then suddenly die at a stoplight. After checking all the basics, we hooked up our high-level scanner and monitored the PCM’s data stream. We noticed the injector pulse width commands were becoming erratic just before it would stall. A quick swap with a known-good, programmed PCM confirmed our suspicion: the original computer’s internal processor was failing under thermal load. The owner had spent hundreds on parts he didn’t need, when the core issue was the PCM itself. This is a classic scenario for these vehicles.
Symptoms of a Failing GM Engine Computer
A faulty PCM can manifest in numerous ways, often mimicking other component failures. If your vehicle is experiencing any of the following, it’s time to consider a 1998 Astro PCM replacement:
- ✔ Check Engine Light is on with various, often inconsistent, trouble codes.
- ✔ Engine cranks but refuses to start.
- ✔ Unexplained drops in fuel efficiency.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ The engine stalls unexpectedly, either while driving or at idle.
- ✔ Noticeable loss of power and poor acceleration.
- ✔ Failure to pass an emissions or smog test.
- ✔ Communication errors with diagnostic scan tools.
The Simple, Cost-Effective Solution
Replacing your vehicle’s PCM doesn’t have to be a complicated or expensive ordeal. Our process is designed for the DIY mechanic and professional alike. Simply purchase this module and provide us with your VIN during or after checkout. Our technicians will handle the complex programming, ensuring all factory settings and vehicle-specific parameters are correctly loaded. When you receive the part, installation is typically straightforward:
- Disconnect the Battery: Always start by disconnecting the negative battery terminal for safety.
- Locate the Old PCM: On the 1998 Astro and Safari, the PCM is located in the engine compartment on the driver’s side, near the battery.
- Swap the Modules: Carefully disconnect the wiring harnesses and unbolt the old computer. Install the new one in its place and securely reconnect the harnesses.
- Reconnect the Battery: Once the new module is installed, reconnect the battery.
- Perform Security Relearn (if needed): In some cases, you may need to perform a simple security relearn procedure, which can typically be done without special tools. This involves a sequence of turning the key on and off. Instructions are widely available online for GM’s Passlock system.
This direct-fit 1998 Astro PCM replacement is also the correct module for a wide array of other GM vehicles from that era, including the S10, Blazer, Suburban, Tahoe, and Express/Savana vans. Please verify your original part number against our cross-reference list (09355699, 16266645, 16250279, 16258815, 09366810) and consult the detailed fitment chart to confirm compatibility.
Frequently Asked Questions
How do I provide my vehicle’s VIN?
After you complete your purchase, you can add your 17-digit VIN to the order notes or send it to us via email with your order number. We cannot ship the module until we have your VIN to program it.
Is this a new part?
No, this is a thoroughly tested, genuine GM part sourced from a salvaged vehicle. This ensures OEM quality and fitment, which is often superior to aftermarket alternatives.
Will I need to do anything else after installation?
The module comes fully programmed for your engine and transmission. However, you may need to perform a simple security relearn procedure (often called Passlock relearn) and a Crankshaft Variation (CASE) relearn, which may require a capable scan tool.
What if my original part number isn’t an exact match to 9366810?
This module replaces several part numbers, including the very common 09355699. Please check the list of compatible part numbers in the description. As long as your number is on that list, this module will work perfectly for your vehicle.
Will this fix my check engine light?
If the check engine light and associated codes are caused by a faulty PCM, this will resolve the issue. However, if there are other mechanical or electrical problems with your vehicle, this will not fix them. This module will allow for accurate diagnosis of any other potential issues.