Restore Your Vehicle’s Core Performance
Is your 2018 Savana 3500 van or other compatible GM vehicle suddenly refusing to start, running rough, or flashing a check engine light that won’t go away? A faulty Engine Control Module (ECM) is often the culprit behind these frustrating and costly issues. As the brain of your vehicle’s engine, a failing ECM can cause a cascade of problems, from poor fuel economy to a complete no-start situation, bringing your work or daily life to a halt. This replacement ECM, part number 12704475 (also fits 12692069, 12680656, 12686383, 12688528), is the reliable solution you need. We take the guesswork out of the repair by programming the module to your vehicle’s specific VIN with the latest GM software updates before it even ships. This ensures optimal communication and performance once installed.
Case Study: A Tricky Diagnosis
I remember a 2018 Express van from a local plumbing company that came into my shop. The driver reported intermittent stalling and a no-start condition that would happen without warning. They had already replaced the battery and alternator. After scanning, I found a U0100 (Lost Communication With ECM/PCM) code, but it was sporadic. Instead of just throwing parts at it, we checked the ECM power and ground circuits, which were solid. The issue was internal to the module itself; heat soak was causing an intermittent failure of the main processor. Replacing the ECM with a VIN-programmed unit like this one solved the problem permanently and got their work van back on the road, saving them from losing more business.
Is Your Vehicle Showing These ECM Failure Signs?
A failing engine computer can manifest in various ways. If you’re experiencing any of the following, a faulty ECM could be the root cause:
- ✔ Complete no-start or crank-no-start condition.
- ✔ Check Engine Light is on with communication error codes (e.g., U0100).
- ✔ Internal processor failure codes are present (e.g., P0601, P0606).
- ✔ Erratic engine performance, such as stalling, misfiring, or poor acceleration.
- ✔ Reduced fuel economy for no apparent reason.
- ✔ Issues with automatic transmission shifting.
- ✔ Failure to pass state emissions testing.
Your Step-by-Step Installation Guide
Installing your new 2018 Savana 3500 ECM is a straightforward process. While the final security relearn may require a professional scan tool, the physical swap is manageable for a DIY enthusiast.
- Safety First: Always disconnect the negative terminal from your vehicle’s battery and wait at least 10 minutes to allow all modules to power down completely.
- Locate the ECM: On the Savana and Express vans, the ECM is typically found in the left-hand rear of the engine compartment. For other models, its location can vary (e.g., LH front of the engine bay on Silverado/Sierra, or under the dash on a Corvette).
- Disconnect Connectors: Carefully release the locking tabs on the electrical wiring harnesses and pull them straight out from the module. Never force them. Inspect the connectors for any corrosion or bent pins.
- Remove the Old Module: Unbolt the old ECM from its mounting bracket. Keep the hardware, as you will need it for the new module.
- Install the New ECM: Mount your new, pre-programmed ECM onto the bracket and secure it with the original hardware.
- Reconnect Everything: Firmly plug the wiring harnesses back into the new module until they click into place. Reconnect the negative battery terminal.
- Perform Relearn Procedures: Attempt to start the vehicle. If it doesn’t start due to the security system, a Vehicle Theft Deterrent Relearn must be performed using a GM-compatible scan tool (like TIS2Web/Techline Connect). Other procedures like a Crankshaft Variation Relearn may also be necessary for optimal performance. This is the responsibility of the installer.
Verified Fitment Across GM Models
This ECM is a direct-fit replacement for a wide range of General Motors vehicles. Please verify your part number and application from the list below. Providing your VIN at checkout is mandatory to ensure we send you a perfectly matched and programmed module.
- 2018-2019 Chevrolet Corvette
- 2018 Chevrolet Silverado 1500 Pickup (ID 12680656)
- 2018 GMC Sierra 1500 Pickup (ID 12680656)
- 2018 GMC Sierra Denali 1500 (ID 12686383)
- 2018 Cadillac Escalade & Escalade ESV
- 2018 Chevrolet Express 2500/3500 Van (4.3L)
- 2018 GMC Savana 2500/3500 Van (4.3L)
- 2018 Chevrolet Suburban 1500
- 2018 Chevrolet Tahoe
- 2018 GMC Yukon & Yukon XL 1500
- 2018 Cadillac XTS (3.6L, VIN 8, opt LF3)
Frequently Asked Questions
Why do you need my VIN?
Your Vehicle Identification Number (VIN) is essential for us to load the correct, factory-specified software and calibrations for your vehicle’s exact configuration. This ensures proper engine, transmission, and emissions performance.
What is a “theft relearn” and will I need to do it?
The Vehicle Theft Deterrent (VTD) system links your ECM to other modules in the car. When a new ECM is installed, this link is broken. If your vehicle won’t start after installation, a VTD relearn is required to re-establish this security handshake. This must be done with a professional GM programming tool like TIS2Web or Techline Connect.
Is this a plug-and-play part?
It is plug-and-play in the sense that it is pre-programmed for your vehicle and will physically connect without modification. However, as stated, a final security relearn or other setup procedures (like crankshaft position relearn) may be required by the installer for the vehicle to start and run correctly.
Can I install this myself?
Yes, the physical installation is straightforward for someone with basic mechanical skills. However, you must be prepared to have the necessary relearn procedures completed by a qualified mechanic or a shop with the appropriate GM diagnostic equipment if the vehicle does not start or run properly post-installation.
Does this fit a 2018 Savana 3500 ECM?
Absolutely. This module is a confirmed fit for the 2018 GMC Savana 3500 Van equipped with the 4.3L engine, along with many other GM vehicles listed. Providing your VIN guarantees we program it correctly for your specific van.