Restore Peak Performance to Your GM Vehicle
If your 1999 Oldsmobile Alero or another compatible GM vehicle is suffering from baffling issues like a persistent Check Engine Light, erratic shifting, poor fuel mileage, or a frustrating no-start condition, the culprit is often the very brain of your engine: the Powertrain Control Module (PCM). As a technician with over two decades of experience, I’ve seen firsthand how a failing PCM can cause symptoms that mimic a dozen other problems. This isn’t just a part; it’s the central command center for your engine and transmission. When it falters, your vehicle’s reliability and drivability suffer.
We take the guesswork and high dealership costs out of the equation. This replacement PCM, part number 9357440, is a direct-fit solution. The most critical service we provide is programming it specifically to your vehicle’s Vehicle Identification Number (VIN) before it ships. This ensures it communicates perfectly with your car’s existing systems, loaded with the latest GM software updates. You get a component that’s ready for installation right out of the box, eliminating the need for an expensive trip to the dealer for programming.
Case Study: The Ghost in the Grand Am
A few months back, a 1999 Pontiac Grand Am with the 3.4L V6 came into my bay. The owner was at his wit’s end. He’d replaced plugs, wires, and even a coil pack chasing an intermittent misfire and harsh 1-2 shift. The codes were all over the place and would change after every drive. After checking all the wiring and grounds, my gut told me it was the PCM. We ordered a VIN-programmed unit just like this one. The swap took less than 30 minutes. On the first test drive, the engine was smooth, the transmission shifted like butter, and not a single trouble code returned. It’s a classic example of how a faulty PCM can send you on a wild goose chase, and how the right, correctly programmed part is the only true fix.
Common Signs of a Failing PCM
A failing Powertrain Control Module can manifest in numerous ways. If you’re experiencing any of the following, it’s a strong indicator that your PCM may need replacement. Look out for:
- ✔ Persistent Check Engine Light (CEL) that won’t clear.
- ✔ Unexplained drops in fuel economy.
- ✔ Engine stalling, stumbling, or running rough.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ The vehicle cranks but refuses to start.
- ✔ Failure to pass an emissions or smog test.
- ✔ Stored diagnostic trouble codes (DTCs) such as P0601 (Internal Memory Error), P0606 (PCM Processor Fault), or various communication errors (U-codes).
A Straightforward Guide to Installation
Replacing the PCM on these GM vehicles is a manageable job for a confident DIYer. While specific locations vary slightly by model, the general process is consistent.
- Safety First: Always disconnect the negative terminal from your vehicle’s battery and wait at least 10 minutes to allow capacitors to discharge.
- Locate the PCM: On the 1999 Alero and many Grand Am models, the PCM is found inside the vehicle, on the left-hand (driver’s) side of the center dash area, often accessible by removing the lower dash panel. On some vans like the Venture or Silhouette, it’s in the engine compartment.
- Disconnect the Connectors: Carefully unclip the wiring harness connectors from the old module. These connectors have locking tabs; do not force them. Inspect the pins for any corrosion or damage.
- 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 Module: Mount your new, pre-programmed PCM securely onto the bracket and reconnect the wiring harnesses. Ensure they click firmly into place.
- Reconnect the Battery: Reattach the negative battery terminal.
- Perform Security Relearn (If Necessary): Some GM vehicles require a simple security relearn procedure. This typically involves turning the key to the ‘ON’ position for 10-15 minutes, then off, and repeating two more times before starting the engine. Consult a service manual for your specific model if the vehicle does not start immediately.
Verified Vehicle Compatibility
This module is a direct replacement for service number 9357440 and other compatible numbers. It is guaranteed to fit the following vehicles and engine configurations. Please match your vehicle, year, and engine to the list below. For 1999 models, matching the ID number on your original part is recommended.
ALERO 99: 3.4L, ID 16236757, 9356741, 9357440
ACHIEVA 98: 6-191 (3.1L)
BONNEVILLE 98: All Options
CAMARO 98: 6-231 (3.8L)
CENTURY 98: 6-191 (3.1L)
CUTLASS 98: All Options
CUTLASS 99: ID 16236757
EIGHTY EIGHT 98: All Options
FIREBIRD 98: 6-231 (3.8L)
GRAND AM 98: 6-191 (3.1L)
GRAND AM 99: 3.4L, ID 16236757, 9356741, 9366314, 9357034, 9347440
GRAND PRIX 98: All Options
INTRIGUE 98: All Options
LESABRE 98: 6-231 (3.8L)
LUMINA CAR 98: LH engine compartment
MALIBU 98: 6-191 (3.1L)
MONTE CARLO 98: All Options
PARK AVENUE 98: 6-231 (3.8L)
REGAL 98: All Options
RIVIERA 98: 6-231 (3.8L)
SILHOUETTE 98: LH engine compartment
SKYLARK 98: 6-191 (3.1L)
TRANS SPORT 98: LH engine compartment
VENTURE 98: 6-207 (3.4L)
Frequently Asked Questions
Frequently Asked Questions
How do I provide my VIN number?
After completing your purchase, please send us a message with your 17-digit Vehicle Identification Number (VIN). We cannot program and ship your module without it.
Is this part difficult to install?
For most DIYers with basic tools, this is a straightforward replacement. Since we program the module for you, no special computer equipment is needed for the installation itself. See our installation guide above for the general steps.
Will this fix my check engine light?
If the check engine light and other symptoms are caused by a faulty PCM, this part is the correct solution. It’s crucial to ensure the PCM is the actual problem and not a faulty sensor or wiring issue.
What if my original part number is not 9357440?
This module replaces several service numbers, including 09356741, 16236757, and others listed in the compatibility section. As long as your vehicle is on the list, this part will function correctly once programmed to your VIN.
Do I need to do anything after installation?
In most cases, it’s a plug-and-play installation. Some GM vehicles may require a security relearn procedure, which is a simple process of cycling the key. This does not require any special tools.