Calling electrical experts... have 06/XC70 need some hacking advice

BryonTheCanadian · Post by **BryonTheCanadian** » 22 Jan 2019, 11:37

Hiya Volvo tribe I have a few CEM electrical gremlins: fault in Pass seat, no radio, no 12v plugs and no back up sensors. this great site provided the answers as it points to a bad relay in the CEM...

but seems fixable . See viewtopic.php?f=9&t=75241

My hacker question why could i not simply add a new hot wire to these devices 12 volt plug seems easy enough also maybe pass seat and or the radio ? thx Bry

IslandV70 · Post by **IslandV70** » 22 Jan 2019, 14:23

I suppose you have to weigh the time and money to find all the wires, run them new places to new relays, and figure triggers for those relays vs. just getting the CEM fixed. Parts wouldn't be too bad, but finding the wires and getting new ones run could be a huge PITA and there may be unexpected consequences. Reminds me of putting in an Ipod adapter in my BMW and having it disable the air conditioning

BryonTheCanadian · Post by **BryonTheCanadian** » 22 Jan 2019, 14:27

Thanks but was not going to run relays ?? do i need them ... i suppose the relays are to disable power when the key is off ? Otherwise please remind me why i need them ?

IslandV70 · Post by **IslandV70** » 22 Jan 2019, 14:34

Relays are electromechanical switches. Heavy wires run from the 12 volt supply to the relay to the loads. Very little current is needed to turn the relay itself on and off.
So you can run a heavy wire (say 10-12 gauge) from battery + through a fuse and through a relay to your load(s). You then run a thin wire (say 16 gauge) to a switch or other source of power to control the relay. If you found a fuse or connection to tap into that was on whenever the ignition is on, then your loads would go on and off with the ignition switch.