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If your harness is used one, I recommend check if it shorts and make sure the pins are ok and connection is good.
For the fog lights, you have two options.
CEM faulty physically or software issue.
So, your best cheapest option is purchasing VIDA subscription $80 test it and do total upgrade (free) only $0.01.
Just remember to put the car to factory default before connecting the VIDA.
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Theoretically everything is checked and the wiring is correct, but I am going to make a mini cable and connect the sensors directly to the CEM. to finish discarding.
But I'm very surprised that it is a defective cem.
I will have to go to an official dealer for the update, in my country Spain we do not have access to VIDA in models from 2016 onwards.
Gracias!
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I check my CEM yesterday my CEM part number (31665457) is lower than yours but the main difference is mine is AC Hi and yours is AA LO, that might be it.
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Hello!
interesting, I have seen that there are 5 or 6 different models of cem. I guess that could be it...
Could someone clarify the differences between AC Hi and AA LO?
I can't find it anywhere?
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That's why I say I'm going crazy!
At the wiring level it is correct.
That's why I say I don't know what to do anymore... since I did the test, there is no option for failure.
If it is not an orbit problem, it is a Volvo software problem or it is the CEM.
Do you know if I can change the cem and load my configuration?
Thank you
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Changing the CEM is not simple. As far as I know, they are coded to the VIN and to other ECUs. So getting a used will not work without cloning your current CEM.
CEM cloning is done on the bench with special tools and software.
Connect the sensors and start the car and put the car to Drive or reverse. If there is a real error, you should see on the screen "park assist not available"
Another test is, remove all the front sensors from their connectors and check the CEM output voltage on PIN 1(+) and PIN 3 (-) on each connector. If you get negative value, that means polarity is wrong. Check for the DTCs if you get different ones or same 4.
Then Check continuity on PIN 1(+) and PIN 3 (-) on all connectors, it must be zero. (no continuity) if you have, than there is a short either on of the connectors or inside the CEM.
The final test is testing the sensors.
Put the car to reverse, go to back of the car and block the sensor with thumb, you should hear clicking noise. Do the same for the front ones.
You can also check the resistance between pin1 and pin2. It should be around 10k ohm. If you are seeing no resistance or too high, that means sensor is faulty.
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Frustration is what I have...
I have already done all those tests.
correct indicates "parking assist not available". It is simply as if the CEM did not receive the signal from pin 2 of the sensors.
As I already mentioned, the funny thing is that the left fog light and the 4 left sensors fail, but I can't believe it's an CEM failure, but I don't get anything...
I'm very frustrated and angry.
