2008 XC70 weird central locking problem Topic is solved

cabathome · Post by **cabathome** » 28 Aug 2020, 15:16

Hello from a new member! I will try to outline an issue on my dad's 2008 XC70, which has a chronic issue with the central locking, as in it's been going on for like 2 years. He always took very good care of it which shows in how well it drives and looks, always taken to the local dealer in Kingston ON, as attested by the eye-watering bills in the file he kept. Sadly he died, and his car has fallen to me to sort out and either keep or sell it for his estate affairs.

The issue is with the flaky central locking / key fob operation which even the dealer couldn't sort out, after keeping it for 3 weeks!

In short the fob wont open the doors/unlock/disengage the alarm at all, if the car has sat for more than 1.5-2 hours...you can unlock it with the valet key, and then the fob works fine, as in before opening the door and sounding the alarm, you can hit the unlock button and the car operates as normal, alarm is disengaged etc. If you then lock it with the fob it works fine for that too. and if you return to use it before too long (maybe 60-90mins) it will also work as normal...but any longer than that, you get nada from the fob, and have to use the valet key again. The battery in the fob is new, and the dealer tried a bunch of things and then just shrugged.

Here's what makes it even weirder...if when locked and the fob is not working, I discovered today that if you pull the tailgate latch under the license plate as if to open it, then push the unlock on the fob, the fob's normal function comes back to life, no need for the valet key!?! This only works from the tailgate latch, it doesnt work if you lift a door handle, on any other door. Extra bit of info is that the tailgate electric lift buttons in the car and on the fob dont make it raise, it starts to lift but gets stuck before moving much (you can hear it click) and so you have to open it manually only.

I wonder if there's any idea here on what might be the cause of this or even what to look at tailgate area to zero in on a fix.

Any thoughts appreciated!

cbpitt01 · Post by **cbpitt01** » 28 Aug 2020, 20:11

Welcome to the forums! You’ll find that many members are willing to jump in with suggestions, even if it’s something they’ve not personally experienced. BUT - you might have better luck from the members over in the forum for V70/XC70 2008-2016. This one is for V70/XC70 2001-2007. Good luck!

Post by **darrylrobert** » 28 Aug 2020, 21:25

I would take it to another volvo dealership. Sorry in 20years ive never owned a car fitted with an alarm, is it possible to dissarm the alarm as it sounds like that is the issue?

Sorry for the loss of your father

cabathome · Post by **cabathome** » 04 Sep 2020, 09:28

Thanks Darryl...

FYI I think I figured it out...it's a conflict with the TPMS in the radio frequency receiver. Apparently the keyless remote receiver is shared with the TPMS.

All the while the car was being checked for this locking issue it had it's winters on. There are no TPMS senders in those wheels so the TPMS/low air warning is always on. When I put the summers on it took a while to recalibrate but eventually it worked, the dash warning went out and then the locks started working as normal again. Then the other day the 'low air' warning' came back, and also the locking went back on the fritz again. I filled up the tire that needed air, and the warning extinguished, as expected.

Later that day the key fob started working again! I wasnt cluing in to the connection of these events, but on the way home my low air msg. returned because there is probably a nail or something in that tire (it's definitely losing air)...and low and behold the locking system is flaked out again.

I read the remote is supposed to send a WUP (keyfob wakeup protocol) signal that 'wakes up' the receiver system to accept the keyfob's commands, and this is being blocked by this TPMS conflict issue, which is why you can only 'wake it up' by activating the driver door with the valet key or by pulling on the tailgate latch, at least when there is an actual TPMS condition.

So what do you think is the fix for this TPMS/central locking conflict...because after the winters go back on, the locks will certainly go back on the fritz...and new receiver module? a reprogram at the dealer?

cabathome · Post by **cabathome** » 08 Sep 2020, 16:09

Just to update...the tire that was causing the 'low air' TPMS msg was fixed, and because the low air msg. is now out, the keyfob has worked ever since to unlock the car. But, I assume...as soon as the winter wheels go on (they have no tire pressure transmitters), it will trigger the TPMS, and so of course the locks will go fubar with the remote again.

Any thoughts as to prevent this? Change the remote receiver unit? Or just put transmitters on the winter tires?

Post by **yagger** » 08 Sep 2020, 17:07

There is option to off TPMS config. And your car will forget about tire sensors... )) If it ok for you.

cabathome · Post by **cabathome** » 08 Sep 2020, 17:09

cool...tell me how

Post by **yagger** » 10 Sep 2020, 17:28

cabathome wrote: ↑08 Sep 2020, 17:09 cool...tell me how

there are services like this for example. )

Bear2179 · Post by **Bear2179** » 05 Sep 2024, 20:27

Sorry for the loss of ur dad. I know u posted this in 2020. Just recently bought - 2008 Volvo xc 70 because it had low miles.
I had the fan replaced and then I started having the same problem as you and couldn’t figure out why or how. Dealer was no help they just wanted to sell me a new key fob for 650$! Took it to a local shop and he said he just reprogrammed the key fob. Then for a couple weeks no issues. Last night I caught a flat tire sliced the tire

So replaced it with the spare while I wait for The tire to come in. Woke up this morning and the doors wouldn’t unlock AGAIN and like u once the door was opened the alarm goes off and I can turn it off with the key fob.

I’m going to mention this to the mechanic tomorrow as he as well is all dumbfounded on how this continue to happen to the door locks.
My key and the door that uses the key is warped so I haven’t been able to replace it

times are tough lol . I’m going to try the trunk trick. And show this blog to my mechanic lol
Again thank u for posting this I thought I was losing my mind

eek18 · Post by **eek18** » 17 Jul 2025, 12:01

Same issue, bought an 08 xc70 a couple days ago and the locks worked during the sale and all the way home. woke up the next morning and nothing would unlock. I was aware of the tpms light being on, but I never would have thought it would interfere with the door locks and antitheft. thanks for updating this when you figured out the issue, super helpful!