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Discussion Starter · #1 ·
On the 1978 Shadow 11 I am restoring, I noticed the two wires that connect to the kickdown solenoid were disconnected. I connected a test lamp to the two wires but nothing happened when kickdown switch pressed. Checked wiring and found earth wire faulty. Put new earth wire on and test lamp lit up every time switch pressed. Connected wires back onto solenoid connector and tried pressing the switch but all that did was blow the ignition/kickdown fuse.
Checking for a short at the solenoid did not seem to make sense, so I checked the resistances on a scrap car gearbox and they were very similar.
Can anyone throw any light on the part no. for the solenoid, my parts list does not list it, or perhaps someone has had a similar problem.
There is very little information I can find about this part in a GM400 box.
Any other information around this area is greatly appreciated.

Jake.
 

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Search for TH400 detent solenoid (or solenoid kit) and you'll find more options than you care to browse through.

It gets called the kickdown or downshift switch, but "the official" term for it is detent solenoid. Also, for anyone doing work on the GM Turbohydramatic 400 transmission, if you can lay your hands on a copy of the Ron Sessions book, How to Work With and Modify the Turbo Hydra-Matic 400 Transmission, it's worth its weight in gold. I believe that it is out of print at the moment, but I could be wrong about that.
 

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Discussion Starter · #4 ·
Thank for the above information, great help as usual.
Just one more question, I notice that the detent solenoids for sale, most in USA, have just a single wire and a single terminal transmission case connector. My one is a two wire connector so getting both single wire connector and solenoid should sort the problem out?
Solenoid earthed through the gearbox casing?

As these parts have to come from America, I need to be sure of the correct parts as they can take up to two months to arrive, especially if they get held up in Customs.

Jake.
 

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Hi Jake. . One wire is for the kick down, the other wire for the speed control 30mph switch.

The kickdown earth's through the box.

If these wires are swapped over the fuse will blow.
 

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As these parts have to come from America, I need to be sure of the correct parts as they can take up to two months to arrive, especially if they get held up in Customs.
Jake,

Paul has already answered the "two-wires" question. Now I'm going to throw out a bit of incredulity: Do you mean to tell me that there is not a GM detent solenoid to be had in all of the UK or Europe?

Given the ubiquity of the THM400/TH400 transmission I'd have to believe that there is a source more local to you than the USA, but perhaps not.
 

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Discussion Starter · #7 ·
Jake,

Paul has already answered the "two-wires" question. Now I'm going to throw out a bit of incredulity: Do you mean to tell me that there is not a GM detent solenoid to be had in all of the UK or Europe?

Given the ubiquity of the THM400/TH400 transmission I'd have to believe that there is a source more local to you than the USA, but perhaps not.
I can say Ebay does not have one in the UK and searching for one in the UK still draws a blank, all suppliers in the USA.
I suspect that some auto transmission repair garages have one and I will admit to not contacting Flying Spares. They may have one but I bet it will be cheaper to get one from America!

Jake.
 

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Discussion Starter · #8 ·
Hi Jake. . One wire is for the kick down, the other wire for the speed control 30mph switch.

The kickdown earth's through the box.

If these wires are swapped over the fuse will blow.
Thanks to the post from Paul I have a working kickdown solenoid, or I can hear it clicking when the switch is pressed. After swapping the feed wire, from the kickdown switch, and leaving the other wire off, it appears to work.
If the wire I have left off goes to the speed control then that will be a job late next spring as two other wires, that are involved with the speed control, have been just cut off! That should not affect the running of the car to get it on the road, I hope.
Thanks to you all.

Jake.
 

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Discussion Starter · #10 ·
Did you search for detent solenoid?

I bet you can only get trunk & hood lids in America as well! ;D
Paul.
I bet I did search for detent solenoid along with other combinations. Not important now as I said in my last post, I can hear the solenoid clicking when the kickdown switch is operated.

You said the other wire from the detent solenoid goes to the speed control 30mph switch. Despite only having a quick look at the wiring diagram for the speed control, I can see what is described as the Top Gear Switch, assuming that is the 30mph switch, but any chance you can point me in the right direction as to its position of this switch on the car?

Regards,
Jake.
 

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There is one wire to the kickdown, there are two wires to the box casing connector.

The second connector goes to the top gear switch which is located in the box.

Both the switch and the solenoid earth through the box.

The solenoid has resistance the switch is a direct earth.

Swap the wires at the connector by mistake and now kickdown feed goes through the switch, direct to earth, blows the fuse.

Hope that helps.

Cheers, Paul.
Ps, lots of used and new parts here.
 

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Discussion Starter · #12 ·
There is one wire to the kickdown, there are two wires to the box casing connector.

The second connector goes to the top gear switch which is located in the box.

Both the switch and the solenoid earth through the box.

The solenoid has resistance the switch is a direct earth.

Swap the wires at the connector by mistake and now kickdown feed goes through the switch, direct to earth, blows the fuse.

Hope that helps.

Cheers, Paul.
Ps, lots of used and new parts here.

Yes Paul, that explanation about the 30mph switch and the wiring will be a great help when I eventually try to sort out the speed control. I managed to sort out the heater, air conditioning problems, which there were many, so I cannot believe the speed control will be any worse to sort.
It is a huge advantage having another Shadow to rob parts from.
Paul, thank you very much for your help.

Regards,
Jake.
 
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