Knowledge Base Article 76FE196629 
Dealer Access

Issue
The External PTT from the 25 pin connector (at pin 19) on my FR3000/FR4000 doesn't work.

Resolution
You need to enable this feature in the cloning software. 
1. Navigate to Common Settings -> Expert. 
2. Double-click ACC CH Selector and set ACC CH Selector to Enable. 

Make sure that you press the REMOTE key on the front panel of the repeater.

Category
Systems : Repeaters : FR3000 / FR4000