Volvo: 93 940 overdrive has mind of its own, volvo repair, volvoclub

Question
Well, I've pulled the od relay and would like to check it out before replacing it. What & how do I check it?

thanx,
prothirty6
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The text above is a follow-up to ...

-----Question-----
My 93'-940 has 265k miles + an overdrive with a mind of it's own. Often my tranny shifts into od (which I have never activated) without warning. It even happens when I stop for a light. I can wait for it to self-disengage or pull over/off the engine/and restart and all is well. My local Volvo repair man wants to charge me hundred$ to correct this but I'd like to repair it myself if possible.

Please share your thoughts on the accuracy of an article I found here: http://www.volvoclub.org.uk/faq/TransmissionAuto.html#RemovingShifterKnob      

Thanx for all feedback.

paul
-----Answer-----
Paul,
Ok Paul the way it works is when ever the car is started (the key is cycled) the trans WILL go into OD. The OD relay sees to that. The button is to turn the OD OFF. That is so it will not shift into OD like if you are pulling a trailer and or driving in the mountains.
That being said I have seen many relays go bad and cause the OD not to engage or after driving a distance allow it to engage, so perhaps just a relay is bad and there is no need to pull the knob and wires off. By the way if the knob needs to be pulled then I do agree with you article explaining how to remove the knob.
To try the repair yourself I would start with a new or known good relay and a test drive to begin.

Answer
Paul,
Terminal 15 power in and power to switch on shifter, 31 is ground, 87 power to the OD solenoid. Power is there when the key is on, goes off if button is pushed to turn OD off. So when OD is working there is power and no power when it is not. Turn key on and push  OD button several times and see that it works each time. When the relay gets old it becomes intermittent.