Lights on the gear selector console off; error codes
 

Hi everyone,

I have a problem with my lovely XC90. When driving on a straight road suddenly I felt a jerk and saw error messages on the dash panel urging me for gearbox service. My mechanic diagnosed lack of charging voltage and replaced alternator and the battery.
There are still some problems though.
The lights on the gear lever are off. There is no indication of the current gear on the dash panel. "Gear selector service required" displays on the dash panel.
There are also some error codes in the system:

DDM-0030 Rear view mirror potentiometer Faulty signal
DDM-0032 Rear view mirror potentiometer Faulty signal
TCM-P086013 Gear Shift Module A communication Circuit - General Electrical Failure - Circuit open
CEM-3F03 Shift lock signal Signal too low
BCM-C111768 Stability function - Algorithm Based Failures - Event information
BCM-C006364 Yaw Rate Sensor - Algorithm Based Failures - Signal plausibility failure
BCM-U042862 Invalid Data Received From Steering Angle Sensor Module - Algorithm Based Failures - Signal compare failure
BCM-U041464 Invalid Data Received From Four-Wheel Drive Clutch Control Module - Algorithm Based Failures - Signal plausibility failure
BCM-U042829 Invalid Data Received From Steering Angle Sensor Module – General Signal Failures – Signal signal invalid
BCM-C008216 Brake System Malfunction Indicator - General Electrical Failures – Circuit voltage below threshold


The only symptom for the driver is lack of gear selector console lights and a dash panel error message "Gear Selector Service Required". Apart from that, the car drives fine.

What is causing all these problems? Any ideas? Please let me know

To have multiple failures suddenly occur at the same time on multiple control units is an extremely unlikely event and would have to be triggered by something common to all units, like:

1. Direct lightening strike to the vehicle causing voltage spikes everywhere and killing power and input/output circuits. You would have noticed this. Highly unlikely.

2. Electromagnetic pulse from eg a nuclear bomb. You would have noticed this too. And I would have read it in the newspapers. Highly unlikely.

3. Bad power supply - you already have a new alternator and a new battery so that can be rulled out UNLESS the you had a power 'surge' (unlikely) which destroyed multiple control units in multiple locations at the same time. Highly unlikely.

4. Bad CAN bus data communication between the units. Use VIDA and check if you can interrogate and talk to each and every control unit.
Other forum members have had issues with one control unit (differential electronic module, DEM, mounted under the car by the rear differential) killing the CAN databus, and thus preventing and disrupting communications with multiple control units.

You need to use VIDA and sound logic to diagnose faults like this.
Apply probabilities: the chances of multiple faults simultaeneously on multiple units is nearly 0, so something must have triggered the event.

Given that you have a bunch of primarily drive related issues, I would get under the vehicle and check all vunerable electrical items, especially gearbox connections and the connections to the DEM on the rear differential. Look for any signs of physical damage from eg a stone or sharp object kicked up by the wheels.
Disconnect the DEM at the DEM itself and see what is reported in VIDA.
Don't just pull a fuse, you need to disconnect the connector.

The alternator and the battery are both replaced now but the errors still remain.


That may be possible. It all probably started when I run out of gas a month ago. The car suddenly stopped and I heard some noise from the back, possibly from differential. Maybe this caused DEM failure 2-3 weeks later and consecutive CAN bus failure that shows as lack of communication with so many modules now.

I will check the DEM unit.

Nope, it's not the DEM. I still have no idea what the cause may be

The obvious thing to do is record all the errors codes, then clear them and see what returns within 1 normal drive (go around the block)

Low battery can cause many erroneous faults that are simply related to low voltage. Clear them and if they don't come back, all is OK.

Example:
On my car VIDA shows a few faults which I record and then clear and monitor over time. If they don't come back after a weeks driving, forget about them.
Some have come back, I may have a fault slowly developing with a temperature sensor on the DPF. But not a concern yet.


As for the gear selector, remove the surround around the gear lever and inspect the ribbon cable to the lamp board. Some people have had ribbon cable damage causing indication problems and warning lights, but no mechanical damage.

Connect VIDA and see what communications are possible to the DEM and the TCM (transmission control module). Check all functions of all items with VIDA, you can narrow it down a lot.

The car drives fine now for several months. I only have "Gear selector service required" error on the dash.

I read it may be due to loose connections of the ribbon to the gear selector:

http://www.volvoforums.org.uk/showthread.php?t=185858


I tried disasembling the plastics around gear shifter but I didn't want to bread some hidden latch so I almost got to the connector. Do you possibly have some instructions (PDF?) on how to get to this little grey ribbon wire?

maciejzi

Do update this thread on your progress.

My XC90 just gave me the same error message today when I was about to start the car. Haven't driven the car yet but I gather from your experience you've been fine for several months with that message on the dash? Is the message on always or is it intermittent?

I'm going to hook up VIDA and see what it says

Have you removed the center console trims?

https://i.imgur.com/Oh9xljbl.png

https://i.imgur.com/24g0j0pl.png

But what does VIDA say?
And what happens when you clear the error codes, and go for a short drive.
What error coeds does VIDA show then?

I've scanned mine and it's showing

TCM-0093 Gear selector lever control module communication. Signal high

I've erased it but it keeps coming back. The gear indicator on the dash is working though. No lights at the shifter.