Is Your 1999 Grand Am or Alero Running Rough?
If your 1999 Pontiac Grand Am or Oldsmobile Alero with the 3.4L V6 engine is experiencing perplexing issues like stalling, erratic idling, poor fuel economy, or a persistent Check Engine Light, the root cause might be a failing Engine Control Module (ECM). The ECM is the central computer of your vehicle, responsible for managing everything from fuel injection and spark timing to transmission shifts and emissions controls. When it begins to fail, it can create a cascade of problems that are often difficult to diagnose.
This is a direct replacement ECM, part number 09361733, specifically for your vehicle. We take the guesswork and hassle out of the replacement process. Unlike a generic part from a salvage yard, this unit is meticulously programmed to your vehicle’s specific Vehicle Identification Number (VIN) before it ships. This ensures complete compatibility with your car’s factory settings and anti-theft system, making the installation process as simple as possible.
From the Diagnostic Bay
We had a ’99 Grand Am GT come in that was driving the owner crazy. It would start fine cold, but after 15 minutes of driving, it would start to buck and surge, eventually stalling at stoplights. The check engine light was on with a slew of seemingly unrelated codes—O2 sensor faults, random misfires, and even a transmission communication error. The owner had already replaced the spark plugs, wires, and an O2 sensor with no change. After hooking up our scanner and monitoring live data, we noticed the fuel trim values were going haywire once the engine warmed up. This pointed away from a single sensor and towards the processor making the decisions. We swapped in a correctly programmed ECM, and the car ran perfectly. It’s a classic case of how a failing computer can mimic a dozen other mechanical problems, making a pre-programmed 1999 Grand Am ECM the only true fix.
Common Symptoms of a Failing ECM
- ✔ Persistent Check Engine Light that won’t clear or returns immediately.
- ✔ Unexplained drops in fuel efficiency.
- ✔ Engine stalling or shutting off unexpectedly while driving.
- ✔ Rough or erratic engine idling.
- ✔ Difficulty starting the engine or a complete no-start condition.
- ✔ Noticeable loss of engine power and poor acceleration.
- ✔ Harsh or incorrect automatic transmission shifting.
- ✔ Communication errors with diagnostic scan tools.
Why Choose Our Programmed 1999 Grand Am ECM?
Getting your vehicle back on the road shouldn’t be complicated. Our process is designed for the everyday driver and the professional mechanic alike. When you order from us, you’re not just getting a part; you’re getting a complete solution. We flash the module with the latest GM-certified software updates using your VIN. This critical step ensures that any factory bugs are corrected and that the computer performs optimally with your vehicle’s specific configuration. This means no expensive trips to the dealership for programming, no special tools required, and a true plug-and-play installation.
Installation Process Overview
The ECM on the 1999 Grand Am and Alero is located inside the vehicle, on the driver’s side, under the center of the dashboard. While professional installation is always recommended, the replacement is straightforward for those with mechanical experience.
- Disconnect the Battery: Always disconnect the negative battery terminal before working on any electronic components.
- Locate the ECM: Access the module under the driver’s side dash. You may need to remove a lower dash panel for access.
- Disconnect Connectors: Carefully unplug the electrical harnesses connected to the old ECM.
- Remove the Old Unit: Unbolt the old ECM from its mounting bracket.
- Install the New Unit: Mount your new, pre-programmed ECM and securely reconnect the electrical harnesses.
- Reconnect Battery: Reconnect the negative battery terminal.
- Perform Security Relearn (if necessary): In some cases, a simple security relearn procedure may be required. This typically involves turning the key to the ‘ON’ position for 10-15 minutes. Instructions are readily available online for the GM Passlock system.
By providing a unit that is already matched to your car, we eliminate the most complex and costly part of the job. You can restore your vehicle’s performance and reliability with confidence.
Frequently Asked Questions
Do I need to send you my VIN?
Yes. Providing your VIN is mandatory. We use it to load the correct, vehicle-specific software and updates onto the ECM, ensuring it works perfectly with your Grand Am or Alero right out of the box.
Is this ECM difficult to install?
The ECM is located under the driver’s side dashboard. For someone with basic mechanical skills, the physical replacement is straightforward. Because we program it beforehand, you avoid the need for specialized dealer programming tools.
Will this fix my car’s specific problem?
This ECM will resolve issues directly caused by a faulty engine computer. While the symptoms listed are common for ECM failure, we always recommend a proper diagnosis by a qualified mechanic to rule out other potential problems like bad sensors or wiring issues.
What part numbers does this replace?
This module is a direct replacement for part numbers 09361733 and 9361733. Please ensure your original module has one of these numbers to guarantee compatibility.
Is any additional programming required after installation?
No. The unit arrives fully programmed to your VIN. In some cases, a simple security relearn procedure that you can do yourself may be necessary, which involves a sequence of key turns.