Hi all, looking for some advice from anyone who may have come across a similar issue in the past with either ADCM or CATS.

I've had a warning light on intermittently to start with but now permanently for the adaptive dynamics in my XFR since the 2nd half of last year. It has been on since around the time some work was done at the front of the car, but not in the area where the sensors are - they are mounted high up by the headlight in the XFR as opposed to near the radiator via the arch liner which is where the workshop manual says they are. This means that a pinched or damaged wiring loom from this work is a possibility, but the sensor should be well out of the way of being bashed, or any other parts that were touched. I read the DTCs and the code is C101E-26 which is the right front vertical acceleration sensor value not changing enough, either the sensor itself or the circuit to it. I was in a rush over Christmas so I threw a new sensor on without troubleshooting, which of course had no effect at all. I am now in a position to be able to do some more diagnostics. My first thought was to go into SDD and datalog the sensor values while on a drive, to see if what the DTC was suggesting was true. What I found is confusing.

While driving, the left front sensor value does change. The right front sensor value does not. The values that SDD reports for the sensors are wild though. While the car is sat stationary on my driveway, which is quite steep if that matters, the front left sensor is reporting 2V / 4.4G and the front right sensor is reporting 0.4V / -15.6G. This leads me to suspect that the ADCM/SUMB module is faulty, and I know it is located under the passenger seat in an area where liquid will pool if any is getting in - although I have no issues with my DAB+ or portable audio modules which are in the same location. I have known weird sensor values reported by SDD in the past as well, which have been misleading. For example the values my MAP sensors report seem permanently wrong, and SDD doesn't seem to correct the IAT2 value either. Anyway, here is a photo of the datalogged values:



This weekend I will lift the front passenger seat and do a physical check of the module. I'll get a multimeter on all the wiring between the module and the front sensors, and check continuity on all 3 wires to the sensors, and check the 5VDC and GND connections at each sensor.

The workshop manual does not say that any calibration is required when replacing a sensor, although there are calibration tasks in SDD. I've read that these are complex and require precisely measuring suspension settings, so I'm not planning on doing that on my steep driveway. And either way, this doesn't seem like a calibration issue as the sensor value is constant. Does anyone have any other suggestions? Is the 4.4G reading a mistake in SDD's datalog function, and actually those sensor results for front left look normal? Do the sensors / control module report spurious values unless the vehicle is in motion?

Cheers!

 

Any accompanying & relevant DTCs? Or solely C101E-26?

 

Nothing else from SUMB - I get one comes up saying invalid data from parking brake module sometimes but it's been there the whole time I've owned the car and doesn't really seem relevant.

 

Then it'll likely be wiring or module as you've already changed the sensor. Sensor should be supplied with between 1.9-2.1v. The current voltage is 0.4v.

 

Got to the bottom of it:





New module time, I don't think there's any cleaning that up. The really badly affected pins are 22 and 23 which are the signal from the front right accelerometer and the ground to both front sensors so that ties up with the DTCs I'm seeing. The car has had a windscreen replacement in the past so water could be getting past there but it looks like it's come from above so it could be door seal related.

 

Good job mate.

 

@toxo
Your posts remain relevant and much appreciated.