I have an Ford mondeo mk3 where the air con isn't working and there is no voltage to the pressure sensors. So I was going to look for error codes. However when I connected the obd it can't connect to the on board computer.

In a YouTube video I saw that it could be a few things. As the check engine light turns on when I turn the key to the on position it should have power so the fuse is not the problem. The next step was to look for a short in a sensors, as far as I understood it could be any sensor. What's the best way to check this? Are there some sensors that are more likely that others or easier to check? Assuming that the displaied outside temperature in the dashboard uses the ambient air temperature sensor that's working too.

Thankful for any help you can give me.

  • I would first check all the pins / terminals are at the same height in the plug / socket - if one is not connecting then it won't communicate.
    – Solar Mike
    Jun 11 '19 at 9:13
  • The power actually does come from the ecu(I think alreast)..focus mk2s use the same setup and it's fairly easy for this to happen.. sometimes the unit just powers down or is blocked by immobiliser.. Oct 7 '19 at 19:54

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