Is Your GM Truck or SUV Running Rough? The PCM Might Be the Culprit.
If you’re dealing with a frustrating no-start condition, erratic engine behavior, a persistent Check Engine Light, or poor fuel economy in your 1998 Oldsmobile Bravada or a similar GM vehicle, a failing Powertrain Control Module (PCM) is a very likely cause. The PCM is the electronic brain of your vehicle, responsible for managing everything from fuel injection and ignition timing to transmission shifting and emissions controls. When it begins to fail, it can create a cascade of confusing and seemingly unrelated problems that can be difficult to diagnose.
Internal component failure, often due to age, heat cycles, and electrical stress, can lead to intermittent or complete loss of function. This isn’t just an inconvenience; a faulty PCM can leave you stranded, cause damage to other components like the catalytic converter, and prevent your vehicle from passing an emissions test.
The Direct-Fit, Programmed Solution
This is a genuine, used OEM Powertrain Control Module, part number 9366810 (interchangeable with 09355699 and others), that has been carefully sourced and tested. Unlike a generic part from a local auto parts store, this unit is programmed specifically to your vehicle’s Vehicle Identification Number (VIN). This is a critical step. We flash the module with the latest official GM software updates for your exact make, model, and engine configuration. This ensures that all factory parameters for performance, emissions, and transmission function are perfectly matched to your vehicle, providing a seamless, plug-and-play installation experience.
From the Diagnostic Bay
I once had a 1999 Chevy Tahoe come into the shop with a complaint of a harsh 1-2 shift and a random P0300 (random misfire) code that would come and go. The customer had already replaced the spark plugs, wires, cap, and rotor. We checked fuel pressure and scanned for vacuum leaks—everything looked perfect. On a whim, I tapped on the PCM connector while the engine was running and the engine stumbled. It turned out that corrosion on the PCM pins and internal board fractures were causing intermittent signal loss to the transmission solenoids and ignition coil. Replacing the PCM with a properly programmed unit solved both issues instantly. It’s a reminder that the computer is often the last thing people suspect, but it’s the central hub for everything.
Common Symptoms of a Failing 1998 Bravada PCM
- ✔ Check Engine Light: The light is on, and you may have codes related to sensors, emissions, or internal module failure (e.g., P0601-P0606).
- ✔ No-Start or Hard Starting: The engine cranks but won’t start, or takes an excessively long time to fire up, either hot or cold.
- ✔ Engine Stalling: The vehicle stalls unexpectedly while driving or when coming to a stop.
- ✔ Poor Performance & Fuel Economy: You may notice a significant drop in power, hesitation on acceleration, and a noticeable decrease in MPG.
- ✔ Erratic Transmission Shifting: Harsh shifts, delayed engagement, or getting stuck in a single gear (limp mode).
- ✔ Intermittent Issues: Problems that appear and disappear depending on temperature or driving conditions.
- ✔ Failed Emissions Test: The PCM controls the emissions systems, and a fault will almost certainly cause a test failure.
Installation is Simple, But One Step May Be Required
Once you receive your pre-programmed PCM, the physical installation is straightforward. It typically involves disconnecting the battery, unplugging the electrical connectors from the old module, unbolting it from its bracket, and then installing the new one in the reverse order. However, on many of these GM vehicles, a CASE (Crankshaft Angle Sensor Error) Relearn procedure may be necessary after installation. This procedure synchronizes the new PCM with the crankshaft position sensor and is required to clear certain trouble codes (like P1336). Most professional scan tools can perform this function in a few minutes. Some vehicles may also require a security relearn, which can often be done without a scan tool. We recommend having a qualified technician perform the installation to ensure all necessary relearn procedures are completed correctly.
By providing us with your VIN during checkout, you ensure that you receive a module that is not only physically compatible but electronically identical to the one your vehicle needs. This eliminates the need for expensive dealership programming and gets you back on the road faster. This reliable, tested OEM module is the most effective way to restore your vehicle’s performance and dependability.
Frequently Asked Questions
Do I need to send my old computer in?
No, there is no core charge or need to send your original PCM to us. This is a direct purchase of a replacement module.
What happens if I don’t provide my VIN?
We cannot ship the module without your vehicle’s 17-digit VIN. The programming is essential for the part to function correctly in your vehicle. Please provide your VIN in the notes at checkout or send us a message after your purchase to avoid delays.
Is this part difficult to install?
The physical replacement is typically easy, requiring basic hand tools. However, as mentioned, a CASE relearn or security relearn procedure may be necessary. We recommend professional installation if you are not familiar with these procedures or do not have access to a bi-directional scan tool.
Will this fix my vehicle’s problem for sure?
This part is a direct solution for a failed PCM. While the symptoms listed are very common for PCM failure, they can also be caused by other issues like bad sensors or wiring problems. It is always best to have a proper diagnosis performed by a qualified mechanic before ordering.
What vehicles does this computer fit?
This PCM fits a wide range of 1998-1999 GM trucks and SUVs, including the Chevy/GMC Pickups (1500/2500/3500), Suburban, Tahoe, Yukon, Express/Savana vans, S10/Sonoma, Blazer/Jimmy, and Oldsmobile Bravada, among others. Please verify your part number (9366810 or 09355699) or use the fitment chart to confirm compatibility.