Can you fit a HU650 into a car with an HU-850?

[vtl]

I have no way to test the HU-803 I have. It unfortunately has a scratch on the screen which I might look at swapping from one of the dead units when I get them. I am waiting for the owner of the 02 XC70 to return from a trip in a few weeks to confirm what he has fitted to his car that needs replaced. Otherwise the unit is of no use to me it was just a curiosity for me to try to figure out what fits what years. Looks like 01-04 have the different bezel and the connect differently to the 05-09 P2's. But does than mean if you swapped them as a whole would they not work with their respective heater controls. You then have the complexity of the iQ? air versions of the system. Also would the heater controls need reprogramming? It is all too hard.

I'll let you know when we figure out what unit he needs for his car and see if you would like the HU-803. Sorry no amplifier.

Neil.

-04 and 05- can't be swapped. If anything, they were programmed for a different CAN topology.

[scot850]

Now that is interesting info. I know what Canbus is, but different topology? I understand what you mean, but I'm the guy who likes to challenge (with some safety margin) what is believed and what is actual. Also, I like to see if the norms can be adapted to give others more options as these cars get older and parts become more difficult to find. Hopefully checking wiring colors on the respective diagrams can help reduce the chances of making a fatal error for the car and me!

I'm looking at fitting 07 electric folding mirrors to my 06 V70. The mirror swap is not too bad (especially if you can hack the CEM Pin and program the button to operate it), and the folding and other mirror parts are all compatible, in spite of slight variances on the wiring diagrams (wire color for a couple of wires). The one part that has to be added if you want full operation of the 07 mirror assemblies it to get the turn signal repeaters to work. This can be done with modifying the wiring harness with added wires taking the signal from the side repeater on the fender. I know it can be done but short of doing it I don't know if the bulb monitoring system will throw a hissy fit as I can't find any mention from the 2 videos I've watched if this is a potential issue.

Programming of the button can be done at Volvo, which is what I will do.

On the radio front though, if the parts don't physically fit and bolt down, then it is a pointless folly to start with. But then at least we will know what has to be done to make it physically fit, IF the wiring turns out to be compatible.

Thanks for the input!

Neil.

[vtl]

Now that is interesting info. I know what Canbus is, but different topology? I understand what you mean, but I'm the guy who likes to challenge (with some safety margin) what is believed and what is actual.

In simplified form. Say, Volvo has 2 computers on CAN bus, each having 2 "sensors" that can be read over the bus. In software sources the sensors are addressed using mnemonic names, something like:

ECM-THROTTLE-ANGLE
TCM-INPUT-SHAFT-SPEED
TCM-OUTPUT-SHAFT-SPEED
PEM-DUTY-CYCLE

When software is compiled into binary code, the compiler walks over all such definitions and assigns them a number, so that these sensors become numbers.

CAN ID <1> SENSOR ID <1>
CAN ID <2> SENSOR ID <1>
CAN ID <2> SENSOR ID <2>
CAN ID <3> SENSOR ID <1>

Imagine situation when the next model year has got a software update in TCM, which has a newly added sensor TCM-VALVE-BODY-FUBAR added in the middle of existing sensors:

ECM-THROTTLE-ANGLE
TCM-INPUT-SHAFT-SPEED
TCM-VALVE-BODY-FUBAR
TCM-OUTPUT-SHAFT-SPEED
PEM-DUTY-CYCLE

This all is compiled into:

CAN ID <1> SENSOR ID <1>
CAN ID <2> SENSOR ID <1>
CAN ID <2> SENSOR ID <2>
CAN ID <2> SENSOR ID <3>
CAN ID <3> SENSOR ID <1>

I.e. TCM-OUTPUT-SHAFT-SPEED was 2 in previous sw and is 3 now. So far so good, unless the module is put into an older car, where CEM and other modules are unaware of such change.

The new software can also add a module in the middle of the list, so the new module gets a CAN ID of some other old module, and the rest of IDs above it is shifted by 1. Put this module into older car and now you have two computers on CAN bus that respond to the same CAN ID - a conflict!

This is basically what makes Volvo modules software often incompatible across model years. Rookie engineering mistake, in my opinion, but oh well. Maybe Volvo does not care about its cars still rolling on the roads after 20, 30 years and representing its high reputation in quality and engineering. Or their business model now includes software reprogramming fees for small shop and individuals. Don't want to buy a new Volvo? You gonna pay for that!

[scot850]

Thanks for taking al that time to explain that for those of us who hate electrical stuff. I kind of understood how it works, but this helps make it more clear. Still does not help me to read Volvo Canbus wiring diagrams. I hate it when they only give some of the wires that run to a module but not all of them. Good example is my challenge with the electrical folding door mirrors and trying to fit 07 mirrors to an 06 car.

It also does not help that there are spare wires in the harness but no explanation for what they are for. What also does not help is that there are redundant wires in harnesses but they can be in an earlier model, but just not sued and are for future plans. For example the 06 door mirrors have one wire that runs to the same pin# as for an 07 uses for the mirror turn signal repeaters. There is no mention of this wire or where it goes. It is this wire I would use to connect the fender side repeater to so the door repeater also works. However, not knowing if the side repeaters are monitored makes this more challenging. I guess I have to remove one and take out the bulb and see what happens. If there is no hissy fit from the monitoring system then all is good!

Again, vtl, really appreciate you taking the time to explain this for luddites like me!

Neil.