wiring of rear height sensor - air suspension

[rschleicher]

I'm looking for the wire color coding (or a wiring diagram) that shows the wires to the rear height sensor for the air suspension. (for a 2000 Expedition, 4x4). I am having an intermittent issue with my rear ride height (and all of the usual suspects of the air suspension are recently replaced - including the rear air springs, the front air shocks, the compressor, and the compressor relay). It seems like either the rear height sensor is intermittently sending an incorrect height signal to the suspension control module, or else the module itself is flaking out occasionally. The rear height sensor has three wires to it, red, black, and white. I assume they are power in (from the module to the sensor), ground, and a voltage output from the sensor. But I haven't been able to find anything that says which wire is which. Also, if the power lead is just a fused 12 volts, or some lower voltage being provided by the module. The sensor has a little electronic circuit board inside of it, and my intent is to power it up while out of the car, to see if I can spot any intermittent behavior. But I don't want to risk damaging it by applying power on the wrong wires... Thanks, if you have a wiring diagram that shows this!

[bnovak]

have you tried probing the vehicle side connector? Go figure - the manual that I have doesn't have the wiring for the air suspension, rather just has a wire going off to the module. The input side of the RAS is 12V though, so I'd guess that the sensors are running 12V as well.

I would probe for voltage on the vehicle side though - that'll at least tell you what to hook it to on the bench.

Also, did you check the actual mounting bracket before removing the sensor? I thought I remember reading a post about the sensor moving in the mount and showing an incorrect height.

[rschleicher]

Thanks for the suggestion - it was my next step in the absence of an actual wiring diagram.