BEHIND THE ASHTRAY IN THE FUSEBOX, A WHITE RELAY STANDING STRAIGHT UP.
allows power distribution to the overdrive solenoid for overdrive engagement.
Behind glove box
Behind the ashtray--google "Volvo 940 overdrive relay" for detailed answers on how to get to it. It's beyond the fuse panel, the white one with black print on the right.
under the dash, driver side
it should be behind the ash tray in the fuse box that is located there.
Remove the fuse from the fuse box. Or remove the relay.
behind the glove In the relay/fuse panel behind the ashtray. After you remove the ashtray and holder you will need to remove the box above it to access the relay
Check either: Solenoid, Wiring, Switch, or OD Relay.
Try a known working relay in its place... I have also put my hand on the relay while someone is driving and pressed the over drive button on and off, you should feel the relay "click" inside.
Up through 87 the relay was located behind the ashtray behind the fuses. 88 and up, the relay panel is accessed from the passenger side panel on the side of the center concol. If earlier version, relay "I" - if behind side panel, relay "G".
Please go to this URL. I think 780 has the same relays and locations: http://www.davebarton.com/pdf/relay_87_700.pdf Igor.
behind the front ash tray goggle overdrive relay check the wiring to the overdrive sensor top of the gearbox going by a right hand drive car it is on the passenger side. so you driver side left.Answer # 2The transmission overdrive relay is locate behind the fuse box.The fuse box is located behind the front ashtray.To replace it:Remove the ashtrayAfter you remove the ashtry, pull the cigarrete lighter out, pull the cover of the lighter out, remove two Philips screws and remove the box above the ashtray.the overdrive relay will be the one on the second row,far right side