As the title says i have an 09 e38 with 12628990 auto os and cannot get a tach output. The car is wired correctly and I have 08 and 10 ecms that both drive the autometer gauge no problems. I have tried another 09 ecm and flashed several os for testing but no luck with getting either of the 09 ecms to send a tach output. Can any one shed light on this I have a 820k pullup in the circuit and have attached the tune if anyone can shed light?

Thanks

2009 (12628990) L98 A6.tun