Help on Radio Diagnostic CR-905

amcgranaghan · Nov 3rd, 2022, 09:31

I have a Radio in my 940 it is a CR-905, It is displaying Code as the car was garaged since 2006 and battery had gone flat.

I did not have the code for the radio but called Volvo dealer and they gave me the code, when trying the code the code I entered just displayed on the screen and the radio did not unlock.

I thought the code must be wrong so I opened up the radio and got the 12bit number from the diode array and decoded it using he decode app, this gave me the same code as the dealer had given me. So the radio was the original and had not been changed.

I then tested the radio by powering up the radio with the 6 button pressed, this worked and the radio functions worked as expected, but since this is a diagnostic mode it only lasts 15 minutes.

Has anyone seen this behaviour before and can suggest a fix?

Thanks for reading.

Forrest · Nov 3rd, 2022, 10:54

If the radio is displaying CODE you have to leave it powered up showing this for some time between thirty minutes and two hours and it will clear of its own accord. You then need to enter the correct code to be able to use the radio. It is better, if you can, to do this on the bench rather than leaving the ignition in your car switched on for an extended period.

If you are definitely entering the correct code and it isn't working then it is possible that one or more of the diodes has gone bad. You can remove them all and the code then becomes 6666.

amcgranaghan · Nov 4th, 2022, 10:27

Thanks for the Info Forrest I did test the diodes with a multimeter and all seemed fine, I also tried re flowing the solder to no success. I will give the idea of removing them and see if that makes it work

amcgranaghan · Nov 4th, 2022, 13:57

I tried removing the diode array and I get the same behaviour as before I can enter the new code 6666 but the radio still is not active, I have also tried leaving it on for 2 hours plus. Guess the item is faulty.

amcgranaghan · Nov 10th, 2022, 11:05

So I gave up trying to get the old radio working, I decided to fit a cd less usb radio ( Cheap Amazon unit ). I did not like the iso adapter I had bought since it makes the radio stick out way to far.

So I designed one on tinker cad and 3d printed it, very pleased with the result looking quite factory!.

IMG_2512.jpg

3d file here if anyone wants to use it

Nov 3rd, 2022, 09:31	#1
amcgranaghan New Member Last Online: Mar 20th, 2023 10:35 Join Date: Oct 2021 Location: Durham	Help on Radio Diagnostic CR-905 I have a Radio in my 940 it is a CR-905, It is displaying Code as the car was garaged since 2006 and battery had gone flat. I did not have the code for the radio but called Volvo dealer and they gave me the code, when trying the code the code I entered just displayed on the screen and the radio did not unlock. I thought the code must be wrong so I opened up the radio and got the 12bit number from the diode array and decoded it using he decode app, this gave me the same code as the dealer had given me. So the radio was the original and had not been changed. I then tested the radio by powering up the radio with the 6 button pressed, this worked and the radio functions worked as expected, but since this is a diagnostic mode it only lasts 15 minutes. Has anyone seen this behaviour before and can suggest a fix? Thanks for reading. Last edited by amcgranaghan; Nov 3rd, 2022 at 10:06.

Nov 4th, 2022, 10:27	#3
amcgranaghan New Member Last Online: Mar 20th, 2023 10:35 Join Date: Oct 2021 Location: Durham	Thanks for the Info Forrest I did test the diodes with a multimeter and all seemed fine, I also tried re flowing the solder to no success. I will give the idea of removing them and see if that makes it work Last edited by amcgranaghan; Nov 4th, 2022 at 10:30.

Nov 10th, 2022, 11:05	#5
amcgranaghan New Member Last Online: Mar 20th, 2023 10:35 Join Date: Oct 2021 Location: Durham	So I gave up trying to get the old radio working, I decided to fit a cd less usb radio ( Cheap Amazon unit ). I did not like the iso adapter I had bought since it makes the radio stick out way to far. So I designed one on tinker cad and 3d printed it, very pleased with the result looking quite factory!. IMG_2512.jpg 3d file here if anyone wants to use it Last edited by amcgranaghan; Nov 10th, 2022 at 13:28.

Nov 3rd, 2022, 10:54	#2
Forrest VOC Member Last Online: Yesterday 23:40 Join Date: Feb 2008 Location: Gloucester	If the radio is displaying CODE you have to leave it powered up showing this for some time between thirty minutes and two hours and it will clear of its own accord. You then need to enter the correct code to be able to use the radio. It is better, if you can, to do this on the bench rather than leaving the ignition in your car switched on for an extended period. If you are definitely entering the correct code and it isn't working then it is possible that one or more of the diodes has gone bad. You can remove them all and the code then becomes 6666.

Nov 4th, 2022, 13:57	#4
amcgranaghan New Member Last Online: Mar 20th, 2023 10:35 Join Date: Oct 2021 Location: Durham	I tried removing the diode array and I get the same behaviour as before I can enter the new code 6666 but the radio still is not active, I have also tried leaving it on for 2 hours plus. Guess the item is faulty.

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