This is a little long, but I’d like to capture all of the steps I’ve taken so far to paint the picture of what is happening. For some background, I picked up a lower mileage (25k mi) 2022 X7 M50i a few months ago.
My wife rode over a curb exiting a shopping center. When the tire dropped back down, it threw a Chassis error. After jacking the rear up, I saw the the plastic ball stud on the height sensor lever arm had snapped. I elected to replace both rear sensors with new BMW sensors and installed metal ball studs as well. This all went without issue.
A few weeks later I felt it would be prudent to replace both front sensors as well, so all sensors would be at similar lifespan. Completed the swap and all was good, other than the front riding a little high. Vehicle did not report any issues. I was out of time for that weekend, so decided to wait until the following weekend to calibrate the VDP to the sensors via ISTA.
Executed the calibration the procedure in ISTA. Upon start up, it threw a Chassis error. I reviewed the fault codes and began diagnosing. The codes steered me to the front right corner being an issue.
- I reviewed live voltage for all four corners and all are within the expected 0.5v-4.5v range. I disconnected the front right lever arm and moved it through its range and see a smooth voltage swing. I do see this corner having lower voltage than the others, however I do not suspect the sensor is the issue.
- I probed the sensor connector and see 4.99V for the supply circuit.
- I checked continuity on the signal wire from the connector at the sensor back to the connector at the VDP and have continuity, so there isn’t a break in the wire. This should have been obvious considering I watched the signal voltage swing in ISTA.
- I looked at the calculated ride heights in ISTA and see -3338mm for the front right corner. This does not change if I move the sensor lever arm (even though the voltage does change).
My conclusion at that point was that the VDP was faulty. I figured I must have shorted that corner’s signal circuit at some point and killed a component within that circuit, causing that math channel to die and just report the -3338mm I was seeing.
I sourced a used replacement VDP from a 2022 X7 M50i on eBay. Swapped it in and programmed/coded it. Happy days! No more errors, I was seeing a normal ride height in ISTA again for the FR corner. I drove it around the block and all was good, no errors. Pulled it into the garage to have a flat spot to calibrate the VDP to the sensors. Went ahead and did so, and upon start up it immediately threw the Chassis error again and I am seeing the same symptoms in ISTA.
Need some direction on where to go with this and where to investigate. Has anyone gone down a similar rabbit hole?