S40 (New) Electrics : Electric Driver's Seat - partial memory failure

[froggyted]

This is a weird one. The seat position isn't held in memory for switch number 3. It will hold in memory intermittently, so that you can toggle back between that and the other positions, but usually after the car is locked and unlocked again the memory seems to have been cleared. I think i've had the problem since owning the car last October but haven't paid it much attention until recently, thinking there had been an error when trying to store the position. However, i've tested it several times today after the memory has annoyingly been lost several times and can confirm there was a fault. I left the seat in postion 3, locked the car, unlocked it, and as i did saw the seat returning to the position stored in switch 2. The weird thing is that a seat position stored in switch 1, which hasn't been used for several months, is still present.

Does anybody have any ideas on this? Surely all 3 switches use the same memory chip? My guess is there is a loose connection to the switch, can anyone suggest anything else?

[SonyVaio]

Originally Posted by froggyted

I left the seat in postion 3, locked the car, unlocked it, and as i did saw the seat returning to the position stored in switch 2

Do you call it Herby by any chance??

[froggyted]

Originally Posted by SonyVaio

Do you call it Herby by any chance??

No, i call her Vivienne, but that's not meant to be public knowledge!

But has anybody got any practical suggestions?

[froggyted]

An update on this: just back from the main dealers where the car was in for them to look at this problem and a failure of the AM waveband on the infotainment system (see separate thread). They say they have done a software upgrade to resolve the seat issue and the car is booked in for next week to have a new IAM to resolve the radio fault, both free of charge under the Select Used Car Warranty. It's too early to know whether the software upgrade has sorted out the seat issue since it was an intermittent problem, i'll report back in a few days time when i know for sure.

[froggyted]

I can now give what i'm fairly certain is a definitive explanation of this problem.

The 'software upgrade' did not resolve the problem, and i told the garage so when i took the car back in for the prearranged audio head unit replacement.

The technician who was replacing the infotainment head unit (which has resolved this issue - see separate thread), came out to chat to me about the electric seat issue. He had looked on the database and had noted that Volvo had flagged a similar problem with the XC60. The cause of this had been identified as people hitting both Switch 3 and the Memory switch at the same time with their leg as they got in and out of the car. He showed me an XC60 in the showroom, and pointed out that it had an identical switch unit to the S40. He suggested that before they replaced the switch module under warranty i should experiment to see if this was the cause of the problem on my vehicle, and since i was on holiday in North Wales the following week (where we covered over 1k miles) i was happy to agree to this.

The two switches being activated by the leg on entry / departure is indeed the cause of the problem. This cancels the position stored in the memory and replaces it with the current seat position (which is likely to be the same as one you have stored in another of the switches). I confirmed this by obscuring switch 3 so that it couldn't be accidentally activated, and sure enough the switch kept the seat position in memory over a sustained period.

I'm amazed that this hasn't been flagged up by other users, especially as the S40 has been in production since 2004.

This imo is a design flaw. It could easily be resolved by Volvo in one of two ways: 1) (the technician's suggestion) by recessing the Memory switch, so that both couldn't be accidentally activated at the same time; 2) (my suggestion) by implementing a software upgrade which deactivates the module as soon as the key is removed from the ignition.

My own chosen low-tech solution to the problem is as follows: a) take a short piece of flat aluminium bar, such as is found in aftermarket radio installation kits (approximately 3 inches); b) bend to a right angle approximately one third of the way along; c) wrap around it a strip of self-adhesive velcro (the soft loop surface) or something similar; d) insert the longer end between the seat and the switch housing so that the shorter end covers switch 3. The bar can then be positioned about half an inch above the actual switch so that a finger can still fit underneath it to activate the switch. The velcro covering helps to keep the bar in the desired position, and also avoids any metal contact that might scratch your finger or the plastics of the switch assembly. It's also more aesthectically pleasing / discreet than the bare bar (i used black velcro).

[chilton55555]

I have suffered the same problems with my XC60 and after reading your thread at last I now have a logical explanation. It only happens when my wife drives the car and I honestly thought she was pressing the memory set button along with her seat position switch, which she vigorously denied!! After reading this the penny has now dropped. I am over six foot and clear the buttons upon entry and exit but my wife is only 5' 4'' and catches them when driving the car. Thanks for posting this issue along with the cause and your bespoke fix.

[froggyted]

Originally Posted by chilton55555

I have suffered the same problems with my XC60 and after reading your thread at last I now have a logical explanation. It only happens when my wife drives the car and I honestly thought she was pressing the memory set button along with her seat position switch, which she vigorously denied!! After reading this the penny has now dropped. I am over six foot and clear the buttons upon entry and exit but my wife is only 5' 4'' and catches them when driving the car. Thanks for posting this issue along with the cause and your bespoke fix.

I'm glad that this has been of use to you, and can confirm that my fix for the problem has worked over a sustained period -with one proviso: if any of the memory positions involve a large amount of movement up and down of the front of the seat cushion it may move the bar out of position, since it is attached by the velcro to part of the seat fabric hidden below the switch housing. No other adjustments (seat height/seat fore and aft/backrest) cause any problems. I'm reluctant to deface the vehicle in any permanent way, and my fix works well for me since my partner uses a similar seat position but with the seat a bit more forward and the backrest slightly altered, but if the fix doesn't work for you an alternative would be to screw or glue the bar to the plastic switch housing so that it is in no way affected by up and down movement of the front of the cushion. An easier alternative of course would be to let your wife have one of the other two seat positions, although if you're like me you prefer to have two different presets for different driving conditions.

Interestingly, i am 5'10", closer to your height than your wife's, but still experienced the problem.

A little amendment to my fix description however: whilst you should use the soft loop surface of the Velcro for the visible upper portion of the bar (more aesthetically pleasing and softer to the touch) you need to use a strip of the HOOK material for the lower (hidden) part, otherwise it won't attach to the seat material and won't remain in place. This is what i did from the start; i simply worded it sloppily in the earlier posting which i can't now post-edit.

The engineer that did my radio head unit said he would flag my feedback to Volvo, and since they are already aware of the problem on the XC60 hopefully they will redesign the switch assembly for future models.

[chilton55555]

Hi, thanks for your help in identifying the root cause of the problem. I had a couple of BLACKSPUR METAL DUAL HOOKS (£2.70 for a set of 5 via amazon UK) left over from a garage re-org. One fitted perfectly over the memory store switching my XC60, it is slightly sprung and stays in place and allows sufficient space to be able to still access the store button if so desired. You would think it was designed specifically to overcome this problem. To make the job look more professional I then covered the entire hook in black plastic insulation tape and fitted it in place. I looks like it is just part of the seat adjustment mechanism, does not move and importantly I have had no more seat memory problems. Once again thanks for your help.

[froggyted]

Originally Posted by chilton55555

Hi, thanks for your help in identifying the root cause of the problem. I had a couple of BLACKSPUR METAL DUAL HOOKS (£2.70 for a set of 5 via amazon UK) left over from a garage re-org. One fitted perfectly over the memory store switching my XC60, it is slightly sprung and stays in place and allows sufficient space to be able to still access the store button if so desired. You would think it was designed specifically to overcome this problem. To make the job look more professional I then covered the entire hook in black plastic insulation tape and fitted it in place. I looks like it is just part of the seat adjustment mechanism, does not move and importantly I have had no more seat memory problems. Once again thanks for your help.

It sounds good Chilton. Check that it remains in place when you raise and lower the front of the seat cushion because this is the movement that's most likely to cause a problem, and if it's ok with that then it looks like you have a perfect fix. I opted to cover switch 3 rather than the memory store switch, since it then leaves the other two positions to function normally (because of the way the switch housing arcs i have never encountered problems with the memories of 1 and 2 being annulled - it seems they are too far away from the memory store switch for both to be activated at the same time by leg movements).