Volvo 740 GLT 1990

[Peterquest]

This car has electric seats fitted - that is, moved by electric motors. These don't work and we suspect the relay isn't working.
Does anyone know which relay it is and where it is?
Yours Peter

[Laird Scooby]

Originally Posted by Peterquest

This car has electric seats fitted - that is, moved by electric motors. These don't work and we suspect the relay isn't working.
Does anyone know which relay it is and where it is?
Yours Peter

Is the STOP button in or out?

[nemesisthewarlock]

Originally Posted by Laird Scooby

Is the STOP button in or out?

Yep I got caught by that one

[Peterquest]

Thanks. The red lock button is out, fuse changed, suspect relay but don't know where is is.

[Laird Scooby]

Originally Posted by Peterquest

Thanks. The red lock button is out, fuse changed, suspect relay but don't know where is is.

Have you checked to ensure power is reaching the seat? Also the fuses for the seats? Some models have resettable fuses for the seats and/or windows so worth double-checking that.

The big thing is with the Volvo electric seats is the switch contacts tend to suffer lack of use. Use some contact cleaner and spray it in round the edges of the rockers in the switch panel, give it a few minutes to soak in then exercise each switch vigourously several times. Give it a few minutes more then switch the ignition on and try the switches. They may need more exercise but you should find at least one adjustment works - not necessarily in both directions so be careful not to "over-adjust" the seat until you've confirmed the adjustment in the opposite direction works.

[penninepullman]

My cars are 760s, of 1988 & 1989 vintage, and am presuming that the electric seats are similar to your car.
As well as checking that the stop button is not depressed, also ensure none of the others are stuck in forward/back or up/down modes, as this can stop the seat moving.
There is no relay for the seat.
There are two fuses, one which is of the resettable type, as noted by Laird Scooby.
The resettable one, no. 35 on my cars, also protects the heated front seats, so may able to check they are working (assuming your car has them),
The other fuse, no.19 on my cars, also protects other circuits; cigar lighter, door mirrors, tailgate wiper and ECC. Yout car may be different, but as you have changed the fuse, this shouldn't be a problem.
After that it is a case of checking the wiring including the earth; mine are earthed at a point near the relays.

[Laird Scooby]

Originally Posted by penninepullman

My cars are 760s, of 1988 & 1989 vintage, and am presuming that the electric seats are similar to your car.
As well as checking that the stop button is not depressed, also ensure none of the others are stuck in forward/back or up/down modes, as this can stop the seat moving.
There is no relay for the seat.
There are two fuses, one which is of the resettable type, as noted by Laird Scooby.
The resettable one, no. 35 on my cars, also protects the heated front seats, so may able to check they are working (assuming your car has them),
The other fuse, no.19 on my cars, also protects other circuits; cigar lighter, door mirrors, tailgate wiper and ECC. Yout car may be different, but as you have changed the fuse, this shouldn't be a problem.
After that it is a case of checking the wiring including the earth; mine are earthed at a point near the relays.

My set-up is the same as yours, with the OPs being a 740 GLT his fusebox is above the ashtray with the relays behind it in a "Central Electrical Board" i believe Volvo call it. Looking at my diagram of the 91MY 7/940, it appears fuses #3 and #15 are responsible for the control power and motor power respectively in his 740. Also it would appear there are two relays in the seat as well although i'm fairly sure mine doesn't have any.

No indication of where the earth point is on my diagram (not Volvo original) unless it's hidden somewhere less obvious.

As you say though, if the heated seats appear to be working (at least at the switches) then the fuses should be ok as well.

[Peterquest]

Many thanks, will give those ideas a go! Just off on holiday but will get back to you with the outcome!

[Peterquest]

A bit challenging, this issue!
Eventually found that the relevant fuse was not receiving power. This was, presumably, a fault in the wiring/fuse box. This would take quite a bit of work to identify so we connected to a working fuse, the heater fan fuse. It now works and I can put the seats in a position to suit me, rather than a giant. That fuse takes fan full on and seats at the same time.
Interestingly, on examination my son found that our solution had been used before.
Thanks for your thoughts.
Yours Peter

[Laird Scooby]

Glad you got it sorted!

Sadly Volvo electrics aren't the best, certainly not the worst by any stretch of the imagination but i've seen many better. Funny thing is for a company that tends to over-engineer mechanically, they frequently under-engineer electrically. At least it's a pass on the MoT for the seat adjustment now, if it is even tested!