D3 suspension fault nightmare, need help

[Iherbst87]

Hey all. I'm having faults with my suspension again. Right rear height sensor fault, along with invalid data sent from ride level control module fault in the TCCM. The right rear sensor has been replaced twice and i did a calibration, i replaced with wiring from the sensor to the air suspension ecu, pulled the tccm out and all the pics are nice and clean, i did find some small corrosion inside the transfer case control module, cleaned it up and seemed to have been ok, but comes on more and more now with the same faults. All readings to and from the sensor and the eas is fine with no breaks in readings. Can anyone shed some light on this by any chance?Screenshot_20220615-075530_Autel MaxiAP200.jpg

[Graeme]

Did you find any corrosion on the TCCM contacts? If so then the connector pins will have to be cleaned too, best done by removing them from the shells. Sometimes the TCCM pcb is irreparably damaged by corrosion.
However a canbus fault at the TCCM will cause every downstream module to post faults so unlikely a fault with the TCCM.

The suspension module may be faulty if the fault can't be triggered by wriggling the wires at the rear harness connector at the suspension ecu.

[Iherbst87]

Hi Graeme,

No i didn't find any corrosion at any pins anywhere, only at one spot inside the ecu. Ill try put up a photo. I have an Autel and can see all the live data, all the sensors are moving as they should, voltages moving up and down, even a graph shows them moving well with no breakes. 20220530_195133.jpg

[Eric SDV6SE]

When was the last time you checked the compressor and its dessicant?

[Graeme]

TCCM pin corrosion is normally the issue when moisture gets in.

I would try to cause the fault by wriggling the wires in the forward-most connector on the suspension module while the ignition is switched on, including flexing the connector socket a little. You probably already know that that connector is the rear harness connector and includes the canbus pair.

[DiscoDB]

That corrosion on the ECU pins looks bad to me. A bit of moisture and easy to imagine this is causing intermittent faults.

[Iherbst87]

Thanks for the reply guys. I changed the compressor desiccant and changed the compressor completely and made no difference.

Graeme, i have tried to wriggle all the wiring at all the connectors while stationary, ignition on and running, but nothing comes up. It only faults once over a few kms/h, and being a mechanic learning more about landies, is driving me nuts.

Yes that corrosion did seem to be nothing, i cleaned it up and flowed the solder on pretty much every accessible spot i could, and still no change. I live about 5 hours from the nearest place to get a part just to 'try' so unfortunately thats out the question at the moment. Do you guys think i am missing something before ordering another transfer case module, or is it maybe the eas module playing up?

[DiscoDB]

When you mentioned you can see the live values moving as expected, is the left and right rear giving different values or are they always identical? (They should be different).

Does sound like damaged wiring, or a bad connection, or a bad splice somewhere. The TCCM could also be damaged if any of those corroded pins did create a short.

[Graeme]

That corrosion on the ECU pins looks bad to me. A bit of moisture and easy to imagine this is causing intermittent faults.

There's certainly a lot of rubbish between the legs.

[PeterOZ]

Hi Graeme,

No i didn't find any corrosion at any pins anywhere, only at one spot inside the ecu. Ill try put up a photo. I have an Autel and can see all the live data, all the sensors are moving as they should, voltages moving up and down, even a graph shows them moving well with no breakes. 20220530_195133.jpg

You will be getting dendrites within that corrosion which can cause erratic operation. See if you can clean those up with isopropyl alcohol.