Is Your 1999 Escalade Running Rough? The PCM Might Be the Culprit.
The Powertrain Control Module, or PCM, is the electronic brain of your 1999 Cadillac Escalade. It’s responsible for managing everything from the engine’s fuel mixture and ignition timing to the transmission’s shift points. When this critical component begins to fail, it can cause a wide range of frustrating and often confusing symptoms. From a sudden drop in fuel economy to a no-start condition that leaves you stranded, a faulty PCM can bring your entire vehicle to a halt. This isn’t just an inconvenience; it’s a critical failure that compromises your vehicle’s performance, reliability, and emissions control.
From the Diagnostic Bay
We had a 1999 GMC Yukon Denali, which shares its platform with the Escalade, come into the shop with an intermittent no-start and stalling issue. The owner had already replaced the fuel pump and ignition coil, but the problem persisted. After connecting our scan tool, we noticed erratic data from several sensors and communication dropouts. We traced the wiring and found no faults. The final diagnosis pointed directly to an internal failure in the PCM. Once we installed a correctly programmed replacement module, the Yukon fired up instantly and ran perfectly. This experience highlights how a failing PCM can mimic other component failures, making accurate diagnosis key.
Common Symptoms of a Failing 1999 Escalade PCM
If you’re experiencing any of the following issues, it’s a strong indication that your vehicle’s engine computer needs attention. A failing PCM can manifest in various ways, often starting as minor annoyances before escalating into major problems.
- ✔ Check Engine Light is illuminated, often with communication-related error codes (U-codes) or multiple, seemingly unrelated sensor codes.
- ✔ Engine stalling, stumbling, or misfiring for no apparent reason.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ A complete no-start condition where the engine cranks but won’t fire up.
- ✔ Noticeable decrease in fuel efficiency.
- ✔ Failure to pass an emissions or smog test.
- ✔ Intermittent electrical issues affecting gauges or other modules.
The Direct-Fit, Programmed Solution
This is a genuine, used OEM Powertrain Control Module, part number 09355699, which has been meticulously tested and is ready for installation in your vehicle. The key to a successful repair is proper programming. We take the guesswork out of the process. Before we ship your part, our technicians will program it using your vehicle’s unique Vehicle Identification Number (VIN). This ensures that the module has the correct software and calibrations specifically for your Escalade’s engine, transmission, and options. It’s loaded with the latest GM software updates, often correcting factory drivability issues and improving overall performance and efficiency.
By choosing this pre-programmed module, you are getting a cost-effective and reliable solution. You avoid the high cost of a new part from the dealership and the hassle of finding a shop with the expensive equipment needed to program a blank module. This part is a direct replacement for several part numbers, including 16266645, 9355699, 16250279, 16258815, 09366810, and 9366810, and fits a wide range of 1998-1999 GM trucks, vans, and SUVs.
Frequently Asked Questions
Do I need to do any programming myself?
No. We handle the main programming for you. Simply provide your vehicle’s VIN at checkout, and we will flash the module with the latest GM software specific to your vehicle before shipping.
Is this part truly plug-and-play?
For most vehicles, yes. However, due to the GM Passlock/VATS anti-theft system, you may need to perform a simple security relearn procedure after installation. This procedure can be done yourself in about 30 minutes without any special tools and instructions are readily available online.
How do I provide my VIN?
After you complete your purchase, you can send us a message with your 17-digit VIN. We cannot ship the part until we receive this information, as the programming is essential for the part to function in your vehicle.
Is this a new part?
No, this is a high-quality, tested, and fully functional used OEM part sourced from a salvaged vehicle. This provides OEM reliability at a fraction of the cost of a new unit.
Where is the PCM located on a 1999 Escalade?
On the 1999 Cadillac Escalade, the PCM is typically located in the engine compartment on the driver’s side, often near the firewall or inner fender.