1990 240DL Overdrive Relay

[apaquette]

I have a 1990 240 DL automatic transmission purchased new which now has 208K miles.
It sometimes was sluggish shifting into overdrive but now completely refused to shift into OD.
The shift lever OD switch works but the vehicle refuses to shift into OD regardless of switch setting or speed.
Is this most likely a OD relay problem?
If so, where is the relay and how do I get access to it ?

[TAFinley]

There are three things you need to check before getting into internal transmission issues:

1) Is the overdrive relay working? When you click the button on the shifter, does the overdrive light on the dashboard toggle between on and off? If the overdrive light does not toggle on/off, then it's probable that the relay has failed and needs to be replaced. The relay is fastened to a clip to the left of the glovebox. The glovebox must be removed to access the relay.

2) If the relay toggles the dash light on/off, then the relay is OK. Check the wiring going from the relay to the overdrive solenoid on the trans. Volvo routed this wiring on top of the trans. It can chafe and short against the trans case.

3) Check the overdrive solenoid. These are pretty rugged, but they do fail on occasionally. If you apply 12 volts to it from the battery, you should hear it click open.

If all three of these checks are OK, then you're looking at an internal problem.