Memoryglide-function on power seats

[Lager]

#12007

I read through the “buying tips” – section.

It says there that the memoryglide-function on power seats is included in model years 1989-1991.

According to my owners manual it´s included in 1987 model year. Haven´t been able to test it yet but it should be there.

By the way I have seen some Powerseat-ECUs on ebay. How often do these fail?

[Davies]

#12008

Good question. I know the mechanics of the switch were totally redesigned for 90 and 91. A big issue was safety so that the seats would stop if something (or someone) was in the way, so they wouldn’t crush a person trying to get in. I assumed that the 87 and 88 would move but not go back to the prior seat position. Good to know. Yes, test and let us know. We can correct if that isn’t the right information.

[Davies]

#12057

Most failures with ECUs have to do with the switches needing to be cleaned.

[Johan Vlagsma]

#12097

Hi, I’ve had a problem with a seat ECU on my ’90 Coupe. Probably due to water coming in from the sunroof onto the seats and leaking through, some of the traces on the printed circuit board had blown off. I fixed them and got it to work with the manual controls again but the memory function never did work again even after replacing the counter chip. I’ve given up fixing it for now and just bought one of the two ECU’s Lager mentions from ebay. Installing it will be a job for this summer. The ECU is a very basic, mostly analog circuit. It has no software, no processor etc. but it is steering the relais and thus essential also for the manual seat controls.

[Lager]

#12278

Hi,

Where are those ECU´s located? The memoryglide-function doesn´t work on my 1987 car. It should have that function because it is written on the owners manual.

 

 

[dn010]

#12279

There is a black plastic box bolted underneath the seat, on the bottom of the seat itself. It is fairly thin and rectangular. I believe this box is what houses the electronics for the seat.

[dn010]

#12281

I apologize for the large picture and dirty background – this is my spare power seat that has been sitting for years on end. I believe the box hanging down is the ECU you’re looking for.

 

[dn010]

#12282

I will add that it is much easier and faster to remove the seat in order to work underneath it, then it is to do anything with it installed.

[Lager]

#12284

Thank you for your reply! So that ecu should be responsible for the “memoryglide-failing” ?

[dn010]

#12287

Are you having trouble with one or both of your seats? Unless you had flood damage, it would be strange that both seats do not work – both seats have their own plastic box. I believe this is the ECU however I am not 100% certain so perhaps it would be best to wait for others to chime in before you start throwing money at it.

[Johan Vlagsma]

#12290

It is not an ECU, just a simple mostly analogue electronic circuit. Mine failed due to water damage and I repaired some of the tracks that blew off the circuit board. Never got it totally working correct though. I think there are 2 versions to these boxes, they are different for the phase 1 and 2 780’s. Just the phase 2 has the memory function I think.

[Lager]

#12291

Both of my seats have non-working memory-glide function. I don´t know if 1987 is phase 1 or 2 but the owner´s manual says that it should have that function. I don´t know about the flood damage – I have only had this car for about one year.

[dn010]

#12311

It doesn’t have to be “flood” damage, even moisture in the carpet from a sunroof accidently left open during a rain storm can cause damage to the electrical components under the seat.

[Lager]

#12665

Can someone confirm that the “ECU” is responsible if the seats don´t move backwards and back automatically when someone enters the rear seat?

[Johan Vlagsma]

#12667

All the buttons and switches related to the seat command the “ECU” or seat controller box and that in turn commands the relays for the motors. If the seats don’t move and the mechanics are not blocked and the buttons and switches work and the internal microswitches in the seat work (there are a couple), then it must be the seat controller box at fault. With the seat out of the car the seat just needs power and can be fully tested, it can be considered a stand alone system.

You say the seats move back automatically. This is not how it is supposed to work. The box just remembers the position the seat came from when automatically moving the seat forward after moving the backrest forward. When you move the backrest back into normal position you must press down the handle on the backrest for the seat to slide back into the original horizontal position. It is semi-automatic, so automatic moving forward, manual moving backwards to the “remembered” position.

[Lager]

#12668

I meant that the seats should move forward automatically when someone enters the rear seat. Sorry I wrote it wrong. My seats don´t move forward automatically when I move the backrest forward. The seats are working when I push the buttons.

[Davies]

#12684

I have the same problem on my 1990 where all the main buttons work but the side seat release lever/button will tilt the seat up, but it only moves the seat about 50% of the time. There must be a short in that release button, as I can always move the seat up with the main control button.   Same problem as you are experiencing.  Seems common. Any ideas on where the failure point it located?

From my research, both 780s Gen 1 and 2 had memory glide features. There was a difference in the release button on the side, which changed in 1990.  Volvo engineer Sven-Gunnar actually redesigned it on a napkin on a flight from Turin to Gothenburg around 1989.  There were concerns for ease of use, as the newer button sticks out and is easier to hold. I can find out who much of the technical aspects are different.  There were safety concerns with the Gen 1 that may have resulted in different technology in order to make sure the seat stops and backs up if someone is trying to crawl out and the seat could potentially crush the if it didn’t stop.

[Author]

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