GM J2534 Pass-Thru Device Setup for SPS2 / GDS2 / Techline Connect (AEZ Flasher 3, MDI 2)
How to set up a J2534 pass-thru device - AEZ Flasher 3, GM MDI / MDI 2, or other approved interface - for GM programming through Techline Connect, including driver install order, J2534 Toolbox verification, and sharing one device across GM and Chrysler.
Setting up a J2534 pass-thru device for GM is an Installation & Setup task that depends on three things being right: a supported Windows version, the correct install order, and active subscriptions on both the GM side and the device side. This guide covers the J2534 device itself — the AEZ Flasher 3, GM MDI / MDI 2, or another approved pass-thru — for use with GM Techline Connect, SPS2, and GDS2. For creating the ACDelco TDS account, buying a VIN slot, and the full Techline Connect install, follow the GM Techline Connect setup articles first, then return here to configure the device.
Prerequisites before setting up the J2534 device
Confirm all of the following before installing anything:
- Windows 11 Pro (Windows 10 and Windows 11 Home are no longer supported for current GM software).
- 16 GB RAM recommended for SPS2 programming (8 GB minimum).
- ~100 GB of free disk space.
- An active ACDelco TDS account with a Techline Connect subscription and a VIN slot for the vehicle.
- A supported J2534 pass-thru device - AEZ Flasher 3, GM MDI / MDI 2, MaxiFlash Elite, Cardak Plus, or compatible.
Step 1 - Install GM Techline Connect first
The pass-thru drivers must go on after Techline Connect, not before. Install Techline Connect from your ACDelco TDS account (acdelcotds.com → download the full installer, run as administrator, launch from the browser as described in the GM Techline Connect setup guide). Let it reach "Ready" status and finish all first-launch updates before adding the device.
Step 2 - Install the J2534 pass-thru drivers
With Techline Connect installed and updated, install the drivers for your specific device: - AEZ Flasher 3 — install the AEZ Flasher 3 Toolbox / drivers. - GM MDI / MDI 2 — the MDI firmware and drivers update automatically through Techline Connect; do not unplug the MDI during that process. - Cardak Plus — install the DG Technologies drivers. Plug the device directly into the laptop (no USB hubs), and confirm it appears in Device Manager with no warning icons.
Step 3 - Verify the device with J2534 Toolbox
Before programming, confirm the device opens cleanly at the J2534 layer:
1. Open J2534 Toolbox.
2. Confirm the pass-thru device is detected.
3. Run a quick test to confirm it opens without errors.
If J2534 Toolbox returns "could not open selected device": reinstall the device drivers, try a different USB port (directly on the laptop), and confirm the device is still approved for current GM software (some older interfaces have been deprecated). If you have a complimentary 3-day Flasher subscription, ask AE Tools to activate it, then wait about 5 minutes, unplug, and re-plug the device.
Step 4 - Confirm the device in Techline Connect and open GDS2
1. Launch Techline Connect (from the browser) and sign in with your ACDelco TDS credentials.
2. Confirm the pass-thru device is recognized.
3. Open GDS2 and verify GM Global is the active diagnostic package. If GDS2 opens to the wrong make, see the GM Techline Connect / GDS2 setup articles for resetting the active package.
Step 5 - Sharing one J2534 device between GM and Chrysler
An AEZ Flasher 3 can serve both GM programming and Chrysler WiTECH 2.0, provided you have active subscriptions for each and the tool is registered against both:
- GM: an active ACDelco TDS / Techline Connect subscription.
- Chrysler: an active WiTECH 2.0 plus TechAuthority subscription.
Important exception: 2023-and-newer FCA / Stellantis vehicles require a genuine Chrysler MicroPod, not a J2534 pass-thru like the AEZ Flasher 3. For those vehicles you'll need a separate MicroPod - see the article on J2534 issues on WiTECH 2.0 for 2023+ Stellantis vehicles.
Troubleshooting: GM J2534 device not detected or VIN read fails
"The tool sees the Flasher but the VIN read fails"
Confirm the ACDelco TDS subscription is active and includes the entitlements (and a VIN slot) for the vehicle you're working on - some subscriptions are limited to specific coverage.
"J2534 Toolbox sees the AEZ Flasher 3 but Techline Connect doesn't"
Restart Techline Connect with the Flasher already plugged in. If it's still not detected, reinstall the Flasher drivers after Techline Connect is installed (drivers installed before Techline are the usual cause).