QuestionQUESTION: I have a 1949 22nd series. It has overdrive, but the overdrive has not worked since I got the car and began working on it. It runs so well otherwise at this time that I have saved the overdrive for last.
The overdrive will not engage. Here's what I know:
* The dash indicator lamp does not light.
* The car free-wheels at driving speed when I let off the accelerator.
* I don't see a reverse lockout switch anywhere near the shifter shaft.
* There is no voltage on either side of the kickdown switch.
* The lockout switch under the dash is open (6v on one side only), and the cable is pushed in (forward).
* The overdrive relay has three terminals: 1 on the left, two on the right.
--- One of those on the right is marked 'SOL'.
--- There is a fuse block mounted on the front.
--- Both sides of the fuse have 6v.
--- None of the three terminals show any voltage.
You can see the relay and switch here: http://www.webhubcentral.com/misc/overdrive02.jpg
Any troubleshooting help anyone can offer will sure be appreciated!
ANSWER: OK, here goes, the dash indicator light not working tells me that the circuit from the ignition switch is not functioning. The fuse on the relay is full time voltage that when the relay closes will power the solenoid. The electromagnet that will cause the relay to close or open is a function of the ignition circuit. Now the first test. You say that you have 6 volt power to one side of the lockout switch. Is that with the key on? It should be and no power with the key off. If that is correct jump that switch and road test the car. Make a jumper wire out of an inline fuse holder that you can buy at any auto parts store. That way if you have a short the fuse will protect the circuit. With the switch working there should be voltage, measured with a digital voltmeter, at at least two terminals, the ignition terminal and the one leading to the governor. Let me know.
Brad
---------- FOLLOW-UP ----------
QUESTION: Yes, that was with the key on.
With the lockout switch shorted I now get 6v on ONE side of the relay (the right side, terminal NOT marked "SOL"). No voltage on the left side of the relay.
No voltage also on the kickdown switch, but FWIW I did do a resistance check and the switch is working (normally ON, with throttle OFF).
Does this sound like a bad relay? If so, do you think it may be user-serviceable? That is, something I could try and accomplish?
Thanks, Brad, for such a quick reply! I love working on this old car.
ANSWER: That wire on the left side should be a smaller wire and run down to the governor on the overdrive unit. When the road speed gets to about 35 miles per hour the gov switch should close grounding the circuit causing the electromagnet in the relay to close the circuit to the solenoid. If there is no voltage to that wire it indicated that the electromagnetic coil is open. As far as user serviceble, how many thumbs do you have? Let me know what you see now.
Brad
---------- FOLLOW-UP ----------
QUESTION: OK, the relay is on the bench and yes, the coil is open. I guess that answers that!
When I momentarily short the SOL wire to the 6v supply I can hear the solenoid click in.
I checked the price of a replacement relay and it looks like $150. Ouch! I think I need to go shopping around a little bit and find a suitable replacement part.
Anyway, I don't want to burn anything up. However it seems, from looking at the diagram, that I ought to be able to safely connect the solenoid wire to the fused 6v supply and have (likely) a working overdrive. Would you agree with that? Do you think that would work for a while?
AnswerPut a switch in that jumper line under the dash. You don't want the solenoid to energize until you get to about 35 miles per hour and want it to drop out at about 20 miles per hour. We used to do this on our old Mercs to get 6 speeds forward. Good luck.
Brad
