Volvo odometer/mileage is stored in multiple ECUs: the instrument cluster(Drivers information module, DIM),
PSCM (Power Steering Control Module), ABS, TCM(Transmission Control Module）or VDDM(Vehicle Dynamic Domain Host)。

Furthermore, volvo also broadcasts odometer in its CAN messages,
e.g. CAN ID 0x285 every 200ms, byte [2 3 4 ], converted them into km
0x405 every 1000ms byte【5 6 7 】

 

nice share, thanks!. and one of the other fun facts is on the 93-95 850s (and possibly the 900s) with the push button LED code reader, you can also pull the odometer reading (just google or check YouTube.

 

@mt6127 thanks for informing that. I read that B9 03 trick from various posts. Old volvo models use 0x0ffffe protocol.
//Send FFFFE cb 01 B9 03
{
cmd_query[0] = 0xcb;
cmd_query[1] = 0x01;
cmd_query[2] = 0xB9;
cmd_query[3] = 0x03;
}

Besides that, a6 d0 is also used to get odometer valule.
cmd_query[2] = 0xa6;
cmd_query[3] = 0xd0;
cmd_query[4] = 0xd5;
cmd_query[5] = 0x1;

Actually Volvo has its own special "UDS" diagnostic protocol other than other car brands.