How to troubleshoot my overdrive?
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Home away from home
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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. Any troubleshooting help anyone can offer will sure be appreciated!
Posted on: 2008/7/4 13:50
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Re: How to troubleshoot my overdrive?
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Home away from home
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Thanks for the quick reply. Yes, parts of the electromatic have been removed. It was more than I wanted to work on.
I'm going to go out now and short across the lockout switch under the dash and see where I go from there. It's likely that the lockout switch is faulty. I remember the bakelite portion had been damaged, but it looked ok otherwise at the time. Jay
Posted on: 2008/7/4 15:34
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Re: How to troubleshoot my overdrive?
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The lockout switch must be centred on the outer shaft and as mentioned should be powered on both sides when the cable is pushed in. Good place to start. If you ground out the wire on the passenger side of the switch it should make the relay and solenoid click.
Posted on: 2008/7/4 15:40
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Re: How to troubleshoot my overdrive?
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Don't think you want to ground that lockout switch on the R11. It is fed directly off ign switch and feeds power to relay coil. On the R9, it is in the ground complete circuit and will do as you mention. On the R11, to get that relay action the kickdown switch or governor would be only place.
Posted on: 2008/7/4 15:53
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Re: How to troubleshoot my overdrive?
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Thanks, You learn something new every day!
Posted on: 2008/7/4 16:13
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Re: How to troubleshoot my overdrive?
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Home away from home
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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?
Posted on: 2008/7/4 16:46
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Re: How to troubleshoot my overdrive?
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Does sound suspicious. Here is the schematic so you can see that the relay coil is the only thing between the 2 terminals. Just for kicks you can ground the one not having voltage on it just to see if the relay will come in.
Looking at your first pict, it might not be a bad idea to remove and clean all the terminals up and maybe pop the cover and see what things look like inside.
Posted on: 2008/7/4 17:04
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Re: How to troubleshoot my overdrive?
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Home away from home
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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? Jay
Posted on: 2008/7/4 18:11
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Re: How to troubleshoot my overdrive?
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Forum Ambassador
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You'd need a toggle switch to manually engage the solenoid when at speed but there would be no damage. The issue might be when dropping out of OD because the timing between the kickdown switch closing and the solenoid contacts momentarily closing to complete the ignition drop out circuit would be dicy. You might not have the passing power at the instant you need it or the solenoid might try & drop out under load & not succeed.
Addendum: Looks like the issue is going to be finding a relay with 6v coil. Found any number of modern that would be satisfactory & might even fit into the can but only 1 with 6 v coil that can carry the amps. Its a mfg site and no info on who might carry for retail. Wonder if your coil actually open deep internally or maybe the wire connection might have opened close to terminals. Does it smell burned?
Posted on: 2008/7/4 18:41
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