TCM Radio/Data-line Connector wire in stereo harness

Hello T1N world,

I’m trying to install a Pioneer AVH-3500NEX stereo in my 2005 dodge Sprinter. In the OEM stereo wiring harness there is a blue wire in the A2 position that correlates to the label TCM/Radio Data Link Connector. Any idea what this is and where it might connect to (if at all) into my new stereo? Also any ideas for the wire labeled Speed Sensor (blue, white, and red wire)?



Erratic Member
The original Becker radios in the US-delivered T1N Sprinters use the "speed sense" wire to increase volume as you go faster (countering the louder road noise).

It's a pulse whose frequency increases with speed. If memory serves, you get about 1000 pulses per mile.
(so at 60 mph you get 1000 pulses per minute, or 16.7 pulses per second)

According to the T1N service manual, the speed sense wire was a 20 gauge Blue/Red/White wire to pin 9 on the connector.
It's the only 20 gauge wire MB fed to the radio.



I just installed a 3400nex. If I recall, there were two wires I didn’t use. One was the speed sensor wire. I think there was also a blue wire that I believe was used for the optional cellular antenna/audio. I left both unconnected. The service manual has a wiring schematic for the audio. Section 8w-47 is what I used for reference.
Yeah we have been using the '04/'05 wiring diagrams and couldnt find anything so figured we would throw it out there!! Cheers

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