Suspension Level Sensor

[Canna4.6is]

Hey all,

First time posting to the forum, but been kurking in the shadows for quite awhile.

After searching and reading about the self-leveling suspension on my e53 4.6is, I've decided that I need some more experienced input on my issue.

I've had the "Self-leveling Susp. Inac" message for about 6 months. No problems in ride height that i can tell, no leaking bags, and the air compressor is running fine.

So finally got INPA hooked up and read errors which showed right rear sensor. When i pulled up the analog info I saw that sensor was showing around .2V.

So ofc I went ahead and replaced the sensor. Upon starting and clearing error history, the same error returned. Analog info now shows 0V for the right rear sensor.

The question I have is how go about testing (at the connector) the input to the sensor to make sure it is getting what it needs before I return this and get another replacement.

I've attached the info, error report and analog output.

Thanks guys.

[StephenVA]

First question.

How does the wiring and connectors look? Is the sensor upside down? Look on the opposite side to confirm alignment. Double check the arm of the sensor alignment as it will swing either way.

[Canna4.6is]

Good thought, checked orientation of the sensor and arm and everything looks good. Should I expect 5V to the sensor? Anyone bench test a sensor? Maybe the resistance should vary from x to y over the full suspension travel? It would be too easy (not std bmw) for it to behave like a potentiometer.

[Canna4.6is]

So I still have the original sensor... Anyone know a way to bench test one of these. Are these analog? Can I supply 5v to the sensor and get variable voltage out with turning the arm? Are these CAN? Should I have 5V at the connector?

[e39_touring]

I had a similar problem in my old e39 touring/wagon. Turns out a wire to the sensor had broken in the trunk area, a few feet from the connector. It was difficult to diagnose until I started pulling trim out and saw the broken wire.

I doubt you have two bad sensors (old and new) that are bad in the same way. The easiest way to test is use inpa to activate suspension up & down while watching the readings (i think it's in analog values) of the sensor in question. And/or, plug in the new sensor and just move the arm up and down while watching the readings in inpa.

If the readings aren't changing for both sensors, I'd start looking at the wiring. You can pull the connector from the ehc module and at the sensor end and check for continuity going by the color of the wires, or better yet, a pinout from a schematic.

On my wagon, that tested out fine because it was an intermittent break. When I lifted the connector to test, everything checked out OK. It wasn't until I visually traced the wire and saw chaffing that I found the problem.

[Canna4.6is]

Thanks buddy. For some reason, I didn't think to check continuity.😏 I will report back with findings.

[Canna4.6is]

Hey all, so I checked continuity between the sensor and the EHC unit. There are three wires between these components. (+), ground, and signal. All three wires checked out. For the other three on the sensor.... I haven't a clue where they go.

I did check the inpa voltage readings while moving the suspension, and it read 0v the entire time.

Since the wires were ok I wanted to check the supply voltage to make sure it wasn't an EHC fault. Between pins 5 and 7 (+ and ground) showed 4.9V which looks to be correct. (For anyone needing to check this connector, it comes apart very nicely to expose the crimped pin. This was very nice when checking readings.)

At this point I feel pretty confident the sensor (the new one) is bunk. I got the replacement "OEM Replacement" albeit non-bmw sensor off of Amazon. I will now go to the dealer so if the issue persists I won't blame the sensor again.

I will report back when I swap it again.