V50 Electrics : Remote reciever module (RRX)

[Notts Ian]

Good morning,

I have a problem with my remote unlocking not working. The car is a MY2007 V50 2.0d and it doesn't respond to any of the buttons on the remote. I know nothing of the history of this problem as it was there when I bought the car. I only have one remote/key.

This is what I have found out so far.

a) The fob is transmitting something. I have another device using the same frequency and it is receiving the signal but of course cannot decode it.

b) Vida doesn't show any diagnostic trouble codes relating to the RRX.

c) The central locking/unlocking works fine from the inside driver and passenger door switches. This suggests all the CEM to door module comms is fine.

d) The transponder in the end of the key works fine. I can unlock the steering, start the engine and drive OK.

Before I take it to a dealer/specialist I'd like to make sure I've checked everything I can.
Are there any more tests I can do to determine whether the RRX is actually receiving anything? I've not seen anything in Vida but it's a system which is new to me so I could easily have overlooked something.

If the RRX is faulty, could it be replaced with a used one without reprogramming the car? I have no way of knowing for sure whether the car has been programmed to this fob but since the transponder allows starting and driving it would seem likely that this has been done.

All suggestions gratefully received.

Ian.

[Clan]

Originally Posted by Notts Ian

Good morning,

I have a problem with my remote unlocking not working. The car is a MY2007 V50 2.0d and it doesn't respond to any of the buttons on the remote. I know nothing of the history of this problem as it was there when I bought the car. I only have one remote/key.

This is what I have found out so far.

a) The fob is transmitting something. I have another device using the same frequency and it is receiving the signal but of course cannot decode it.

b) Vida doesn't show any diagnostic trouble codes relating to the RRX.

c) The central locking/unlocking works fine from the inside driver and passenger door switches. This suggests all the CEM to door module comms is fine.

d) The transponder in the end of the key works fine. I can unlock the steering, start the engine and drive OK.

Before I take it to a dealer/specialist I'd like to make sure I've checked everything I can.
Are there any more tests I can do to determine whether the RRX is actually receiving anything? I've not seen anything in Vida but it's a system which is new to me so I could easily have overlooked something.

If the RRX is faulty, could it be replaced with a used one without reprogramming the car? I have no way of knowing for sure whether the car has been programmed to this fob but since the transponder allows starting and driving it would seem likely that this has been done.

All suggestions gratefully received.

Ian.

It is most likely the remote fob they can fail after a long time ... That is why having 2 of them is essential , to get your car home and to prove whether the other is faulty . The car is useless without a working remote of course .

[Notts Ian]

Agreed that a second key is essential. Will be getting one soon.

Made some progress today after deciding to go "old school". Removed the RRX from the car and got it on the bench to look inside. It's all fairly normal stuff in there - receiver, microcontroller for decoding and an interface for the LIN bus - so I got the datasheet for the receiver chip and warmed up the oscilloscope and multimeter.

Well, the receiver is receiving fine and the signal from the Volvo fob appears to be decoded as there are pulses visible on the LIN bus terminal. I also tried a different type of fob (same frequency) and although I could see its signals leaving the receiver there was nothing happening on the LIN. This is what I would expect to see and leads me to think it likely that both the fob and the module are OK.

The signal on the LIN is just three short pulses quite widely spaced which I think is the RRX just trying to get the car's attention. The next step will be to put the RRX back in the car and see if the car responds.

Sorry if this post is a bit long but debugging communication networks is part of my day job (but not usually in cars!) and I'm always up for a challenge. Maybe this will help someone else some time.

Ian.

[Alker]

Hi Ian.. this post resonates with an issue I'm having also. Did you ever get a resolution on this ?

[Clan]

Originally Posted by Alker

Hi Ian.. this post resonates with an issue I'm having also. Did you ever get a resolution on this ?

when ever i have come across this problem over the last 15 years on the V50 range it has always been the fob , never ever have i heard of the receiver failing .

[ThomasAO]

Originally Posted by Notts Ian

Agreed that a second key is essential. Will be getting one soon.

Made some progress today after deciding to go "old school". Removed the RRX from the car and got it on the bench to look inside. It's all fairly normal stuff in there - receiver, microcontroller for decoding and an interface for the LIN bus - so I got the datasheet for the receiver chip and warmed up the oscilloscope and multimeter.

Well, the receiver is receiving fine and the signal from the Volvo fob appears to be decoded as there are pulses visible on the LIN bus terminal. I also tried a different type of fob (same frequency) and although I could see its signals leaving the receiver there was nothing happening on the LIN. This is what I would expect to see and leads me to think it likely that both the fob and the module are OK.

The signal on the LIN is just three short pulses quite widely spaced which I think is the RRX just trying to get the car's attention. The next step will be to put the RRX back in the car and see if the car responds.

Sorry if this post is a bit long but debugging communication networks is part of my day job (but not usually in cars!) and I'm always up for a challenge. Maybe this will help someone else some time.

Ian.

Holy thread revivial batman!

Hi Ian did you ever get to the bottom of this as i not have this issue and would like some advise before going to a main steeler

[Kentish Dragon]

Originally Posted by ThomasAO

Holy thread revivial batman!

Hi Ian did you ever get to the bottom of this as i not have this issue and would like some advise before going to a main steeler

Ditto.
I have the exact same remote issues on both fobs....internal locking is fine, both keys start the car, neither remote fob works to lock/unlock.

I read elsewhere that there's a common issue of plug connectors going fubar in the panel under the glovebox. But not being confident with electrics I'm loathed to start messing about there

Any updates or info would be appreciated !!

[ThomasAO]

Originally Posted by Kentish Dragon

Ditto.
I have the exact same remote issues on both fobs....internal locking is fine, both keys start the car, neither remote fob works to lock/unlock.

I read elsewhere that there's a common issue of plug connectors going fubar in the panel under the glovebox. But not being confident with electrics I'm loathed to start messing about there

Any updates or info would be appreciated !!

I tried replacing the RRX module in the headliner above the passenger side sun visor and this hasnt worked.

What is the plug connector issue you mention and i will have a hoke, if i get anything fruitful i will update you.

[Kentish Dragon]

Originally Posted by ThomasAO

I tried replacing the RRX module in the headliner above the passenger side sun visor and this hasnt worked.

What is the plug connector issue you mention and i will have a hoke, if i get anything fruitful i will update you.

Hi.
I was referring to the panel in passenger footwell that folds down below the glovebox. Cabin fuseboard plus relays etc on there. The multiplug connectors there either get dirty, corroded, loose or just fail - according to the posts I read.

If I get some dry days when not working I'll pull the battery and have a poke around with contact cleaner & see if I get any joy - and report back.

[Baker3570]

hi

apologies for jumping on this post, i recently posted in the forum as im having issues with my key.

ive had a new one programmed to the car as i was told it was this but still doesnt work... did you managed to solve your issue?

thanks