Quote Originally Posted by AudiS4 View Post
I am curious if it possible for the Tacho To have a faulty 74HC541.The unit is new I have used it once.Is it possible that the 74HC541 is already no good???I would like to get this solved as most of my work is done on the bench and not in the car.Anyone have anything else to add or that I can check???ALso what do you use to desolder such a small ic and solder it back??
Just one advice to you:
DONT TRUST TU FOR EEPROM READING AND WRITING(especially without desoldering eeprom)!!! You can erase all content of eeprom!
Bye some eeprom programmer with pin check options (for example Elnec Memprog or Beeprog) and you never have problem.

Best regards
Vladimir