Get Your GM Truck Running Right Again
Is your 1998 Chevrolet Astro or another GM truck acting up? Dealing with frustrating issues like random stalling, a persistent check engine light, poor fuel economy, or a dreaded no-start condition can bring your day to a halt. As a technician with over 20 years of experience under the hood, I’ve seen countless vehicles sidelined by a failing Powertrain Control Module (PCM). The PCM is the brain of your engine, and when it starts to fail, it can cause a cascade of confusing and costly problems. This isn’t just an inconvenience; it’s a reliability issue that needs a solid, dependable fix.
This is a reliable, tested, and ready-to-install PCM, part number 9355699. We take the guesswork and extra expense out of the repair. Before we ship this module, our experts will program it with the latest GM software updates specifically for your vehicle using the VIN you provide. This means you get a part that’s not only a direct replacement but also has the most current operational data from the manufacturer, often resolving issues the original software didn’t. This unit is a high-quality component sourced from a salvaged vehicle, offering a smart, economical alternative to expensive dealership parts.
Is Your GM Truck or Van Showing These Signs?
A faulty PCM can manifest in various ways. If you’re experiencing any of the following, a failing engine computer could be the culprit. I’ve often traced these symptoms back to an internal PCM fault, especially the dreaded P0601 code.
- ✔ Check Engine Light is on with communication error codes (like P0601, P0605) or various sensor codes.
- ✔ The engine cranks but refuses to start.
- ✔ Unexplained drops in fuel mileage.
- ✔ The vehicle stalls intermittently, especially when warm.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ Noticeable loss of engine power and performance.
- ✔ Failure to pass an emissions test.
From the Diagnostic Bay
I remember a ’99 Suburban that came into my shop with an intermittent no-start condition that was driving the owner crazy. It would be fine for a week, then leave him stranded. No consistent codes were stored, just a few random communication faults that would clear. After checking all the usual suspects—battery, grounds, fuel pressure—I hooked up my scope to the PCM’s power and ground circuits. While monitoring the data, I tapped on the PCM casing, and the engine immediately stalled. The internal board had a micro-fracture that only broke contact when it got hot or vibrated just right. Replacing the PCM with a properly programmed unit like this one solved the problem for good. It’s often these tricky intermittent issues where the PCM is the silent offender.
Your Straightforward PCM Installation Guide
Installing your programmed 1998 Astro PCM is a manageable job for a DIYer with basic tools. Our VIN programming service handles the most complex part, but you’ll need to perform a security relearn procedure after installation, which is standard for these GM vehicles.
- Safety First: Disconnect the negative terminal from your vehicle’s battery and secure it away from the post to prevent accidental contact.
- Locate the PCM: On most of these vehicles, the PCM is located in the engine compartment, often on the driver’s side fender or near the battery. It’s a silver metal box with several large electrical connectors.
- Disconnect and Remove: Carefully unplug the electrical harnesses. There are typically release tabs or levers on the connectors. Once disconnected, unbolt the PCM from its mounting bracket and remove it from the vehicle.
- Install the New PCM: Mount the new module in place and securely fasten the bolts. Reconnect the electrical harnesses, making sure they click firmly into place.
- Reconnect Battery: Reattach the negative battery terminal.
- Perform Security Relearn (CRITICAL): You must perform the GM Security Relearn Procedure (also known as the Passlock Relearn). 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. Your vehicle will not start until this is completed. Search online for the specific procedure for your model year.
Verified to Fit These GM Models
Please verify your part number is 9355699 or one of the interchangeable numbers (16266645, 16250279, 16258815, 09366810) to ensure compatibility. This module is a confirmed fit for the following vehicles:
- Astro Van: 1998
- Blazer S10 / Jimmy S15: 1998 (4.3L)
- Bravada: 1998 (4.3L)
- Chevrolet/GMC Pickup (1500, 2500, 3500): 1998-1999 (Gasoline Engines)
- Escalade: 1999
- Envoy: 1998
- Express / Savana Van (1500, 2500, 3500): 1998-1999 (Gasoline Engines)
- Isuzu Hombre: 1998 (4.3L)
- S10 / S15 / Sonoma Pickup: 1998 (4.3L)
- Safari Van: 1998
- Suburban (1500, 2500): 1998-1999 (Gasoline Engines)
- Tahoe / Yukon: 1998-1999 (Gasoline Engines)
What exactly is VIN programming?
What exactly is VIN programming?
VIN programming is the process of loading your vehicle’s specific Vehicle Identification Number (VIN) and the latest GM-approved software onto the PCM. This ensures the computer communicates perfectly with your engine, transmission, and security system, just like the original part from the factory.
Is this a new part?
No, this is a thoroughly tested, genuine OEM part that has been sourced from a salvaged vehicle. This provides a reliable and cost-effective solution compared to a new dealership unit, without sacrificing quality or performance.
Do I need to do anything after installing the PCM?
Yes. After physical installation, you MUST perform the GM Security Relearn Procedure. This syncs the new PCM with your vehicle’s anti-theft system. The engine will not run until this procedure is successfully completed. It’s a simple process that does not require special tools.
How do I send you my VIN?
After you complete your purchase, simply send us a message with your 17-digit VIN. We cannot program and ship your 1998 Astro PCM until we receive this information.
What’s the difference between a PCM and an ECM?
The terms are often used interchangeably. ECM stands for Engine Control Module, while PCM means Powertrain Control Module. A PCM is a type of ECM that also controls the transmission and other powertrain functions, which is standard on most modern vehicles like your GM truck or van.