Extra connector under tank on 04????

[GDOG_PITBULL]

I have found a blk yel red wired connector that does not have a mate. Any ideas?
G

 

[pig pen]

You have a tach? If not I bet that is what it is for. Most were prewired for the addition of a bdm tach.

 

[bdmridgeback]

Optional Tach port

 

[Big Mike]

Yup. What they said. I just used mine on my new BDM tach.