The overdrive on my automatic 240 stopped working a while back. I was told it was probably the overdrive relay so I ordered two. Neither of them seem to fix the problem.

Any other common problems? My commute is about to quadruple and OD would be nice.

Fuse is good?

Check the wire from the switch to the relay; look for a momentary 12v at the relay when the button on the shifter is pressed (12v when button is held down, no voltage when released)

With the momentary 12v applied to the relay it should "click". Once you have confirmed a click if you still are not getting the shift into overdrive at the transmission check the wire from the relay to the solenoid on the transmission (check for 12v being supplied to the solenoid)

With 12v supplied to the solenoid you should hear it activate and you should have overdrive. If not post back with what you have found.

Randy

Well I checked and I am getting 12v to the relay. Where is the solenoid on the tranny? Just want to make sure I am checking the correct thing.

thanks,
Nate

On the upper driver's side of the transmission. The wire attached to it should receive 12v when the overdrive arrow is not illuminated on the instrument cluster.

If you find that there is 12v at the solenoid resist the tempatation to immediately tear into removing the solenoid. Read the FAQ's (dropdown menu upper right side of this page) regarding precautions.

Randy

A few more things. which wires are which on the relay? Can I test the relay buy seeing if 12 volts are coming off the "output" wire.

Remove the relay from its connector and look at the relay pins for their numbers, then to the harness connector for the corresponding wire colours:

Pin 31 - Black wire to constant ground
Pin 15 - 2 Blue wires into the connector...one comes from the ign sw., the other goes to the "OD OFF" pushbutton on the gear lever. If they are different sizes, the bigger one is from the ign. sw.

Pin 86 - Gray wire coming back from the pushbutton.
Pin 87 - White wire (output) carrying power to the solenoid.
Pin 87a- Yellow wire to the OD OFF light in the instrument cluster.

Normal operation at ignition on is for the relay to get 12V at #15 and feed 12V to Pin 87 so the solenoid enables 4th/OD when speed and load call for it. As soon as you turn the key on you should see 12V at #15 and #87.

Press the gear lever button and the realy clicks, 12V at 87 is lost, and 87a now has 12V, warning light illuminates, solenoid clicks off.

Press button again, relay and solenoid click(on), light goes out.

This is according to my 1982 factory Green Book. I'm assuming that OD ON is the default and you have to turn it off manually. If so, Pins 87 and 87a don't have the same function as in simple, non-electronic, relays.

--
Bob (son's 81-244GL B21F/M46, dtr's 83-244DL B23F/M46, my 94-944 B230FD and 89 745 (LT-1 V8); hobbycar 77 MGB, and a few old motorcycles)