I checked for cont between the switch and pin 10 of Klima, it was good, pin 1 and ground, it was good, switch and pin 7 I believe of pbu it was good. Pin 13 at pbu is power I believe, if I put positive there and neg pin 7 I show less than a volt, like .6 or something. I even ran a test wire directly from switch to ground, pin 1 of Klima to ground etc thinking it was bad wire also but still no go. Between that and checking ohms on the wires I think the wires are good, there is something I am missing apparently
Sent from my iPhone On Jul 13, 2013, at 7:29 PM, Peter Frederick <psf...@earthlink.net> wrote: > The PBCU provides a ground to the voltage signal, so I suspect you don't have > voltage at the switch due to a failed wire somewhere between the battery and > the pressure switch. > > I almost forgot -- some engines are equipped with a wide open throttle switch > to disconnect the AC compressor at full throttle. If that switch as failed, > you won't get AC engagement and no voltage at the PBCU, just as if the low > pressure switch was open. I don't know where this switch is in the circuit, > but the switch itself is on the throttle linkage. > > Check for voltage at the pin socket for the KLIMA, this is supplied via the > keyswitch. If you don't have voltage at the KLIMA socket for that wire, the > AC won't ever come on as the KLIMA relay cannot be energized. You will have > to check the KLIMA wiring, I'm not sure if that line is separate or > internally connected to the switched positive supply. > > If you have voltage at the switch but not the connector at the PBCU, you have > a wiring failure between the pressure switch and the PBCU or a failed open > pressure switch. You can jumper the switch, but you've tried that, right? > > The system works by the PBCU providing a ground for the relay in the KLIMA, > which can be disconnected by an open pressure switch, a failed speed sensor > signal (engine speed vs compressor speed) or in some cases a temperature or > wide open throttle switch. > > Peter > > > > > > _______________________________________ > http://www.okiebenz.com > For new and used parts go to www.okiebenz.com > To search list archives http://www.okiebenz.com/archive/ > > To Unsubscribe or change delivery options go to: > http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com _______________________________________ http://www.okiebenz.com For new and used parts go to www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://mail.okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
