QuestionI have had issues with a 240GL wagon I purchased recently with the overdrive not working. The switch in the automatic shifter works fine, the gearbox and engine run like a dream but no overdrive. Today I began checking the electrical system and found that position 11 on my fuse panel has no wires at all conected and there is no loose wires in the near vicinity, which leads me to beleive that the entire wiring to this has been pulled out! I need to get my hands on a complete wiring diagram from the box to the fuse panel.
Answer Ross, no one would go to that much trouble to pull all the wires. Well, maybe someone with a severe case of OCD ??? Don't believe the fuse descriptions on the cover or in the owner's manual. Some last minute production changes may have been made.
Slide under the car and locate the O/D solenoid on the O/D unit at the rear of the transmission. The old ones had one wire to them and the new ones had two. It's about the size of a large D type flashlight battery. With a test light, key on, engine off, 4th gear selected, put one end of the test light to a good ground and the other to the wire. Have a helper cycle the switch and see if the light turns on and off. (on a two wire, hook one end of the test light to each wire. If it goes on and off, all control functions are ok. If it does not, have the helper in 4th gear push the shifter hard to the right. If that makesw it work, you have a worn 4th gear interlock switch on the transmission. Trace O/D solenoid wire(s) to locate it. The wire going towards the motor should have 12 volts on it at all times the button is depressed. If you get this far and still no luck, I can help you some more.
Most common pattern failure items in order of frequency, O/D relay located behind heater/radio, a real bugger to get at. O/D button wiring cracked or broken at shifter base. O/D button itself. 4th Gear interlock switch wear. Dirt in O/Drive solenoid orfices or trans. side orfices. O/D solenoid itself. And only once in 26 years, the O/D unit itself. They are almost bullet proof.
Not a real complicated system once you understand how it works. HTH
Mark
