Overdrive wiring, 1958 TR3A

[Napoleon]

Please could someone help with walking me through fitting two new looms to activate the overdrive.

I've been trying to work it out for hours but my electrical knowledge is poor. I have from Moss the two small looms, a relay, and a new overdrive switch.

The new overdrive switch has two long grey wires coming from it.

I don't have any of the original loom(s) so have nothing to compare - except for what is currently wired on the gearbox/overdrive, which looks a bit of a mess.

If someone could annotate which connection goes where on both the looms, I would be very grateful.

The car is now negative earth with an alternator. 

Attached are some pictures of where I'm up to.

Many Thanks, Rod

[RobH]

Right. This is what you should have:

It doesn't look as though the wire colours in your new loom are the same as the diagram but that shouldn't matter. 

Note that the solenoid is only connected to the relay pin C2 and not to the interlock switches as you seem to show it on the sketch.

The relay connections are also wrong. 

The brown wire is  intended to go to C1 (shown brown/white above) while the white wire goes to W1

The yellow/green from relay W2 goes to one of the grey wires from the overdrive switch and the other grey wire joins the yellow from the interlock switches.

I think the looms go like this but the two extra yellow wires are a mystery. They may be intended for other cars where the OD switch is on the steering column where more length is required. You could probably use either pair as long as the unused ones are insulated.

  I have called the OD switch grey wires 1 and 2 to differentiate them but it doesn't matter which is which. 

The brown power wire needs to be connected to the main feed from the alternator but where that is depends on how the conversion was done.

The solenoid also needs an earth connection of course. 

Edited September 15, 2023 by RobH

[Napoleon]

Thank you very much Rob, this is a great help.

Could I ask regarding the interlock switches, which wire goes to which connection on the two switches?

Rod

[RobH]

It doesn't matter which way round the switches are wired Rod, as long as each has one black and one yellow wire. Use the most convenient method. 

[Napoleon]

That's great Rob, a Big Thank You.

Rod

[RogerH]

Here is another version much the same as RobH's

Roger

[Napoleon]

Thank you very much Roger.

Rod

[Napoleon]

Hi Again Rob,

The colours were not clear in my pictures of yesterday - I've redone the pictures as I seem to have two redundant yellow

wires from two different spurs on the first loom - is this correct please? (I've marked them in the new pictures).

Many Thanks

Rod

[RobH]

OK I couldn't see the colours clearly on the earlier photo.  This one helps a lot. 

Yellow/purple from the first spur goes to Yellow/ purple on the second loom

Yellow /green on the second spur goes to one of the grey wires on the OD switch.

Both of the plain yellow wires in the first and second spurs seem to be redundant as you say, and can be insulated and taped out of the way. 

Your labelling of the second loom is correct. 

[Napoleon]

Excellent - much appreciated Rob

Rod

[BlueTR3A-5EKT]

My Diagnosis of the body loom.  

It looks like it is a combination of the loom for A type and J type overdrives.  The A type uses a relay and the J type does not.  

The spare yellow is for  J type use only I suspect where all you have is a live feed through the dash switch down to gearbox isolators then to the solenoid. 
 

I could be mistaken 

[RobH]

More than likely Peter. 

[Napoleon]

10 hours ago, BlueTR3A-5EKT said:

My Diagnosis of the body loom.  

It looks like it is a combination of the loom for A type and J type overdrives.  The A type uses a relay and the J type does not.  

The spare yellow is for  J type use only I suspect where all you have is a live feed through the dash switch down to gearbox isolators then to the solenoid. 
 

I could be mistaken 

Thank you Peter

Rod

[Napoleon]

On 9/15/2023 at 11:22 PM, RobH said:

The brown power wire needs to be connected to the main feed from the alternator but where that is depends on how the conversion was done.

Hi Again, Advice re the brown power wire and also the white wire please - where do I connect these to?

The picture attached shows the way the alternator is connected to the dummy regulator:

Three wires from the alternator, yellow, brown, thicker brown.

The yellow is connected to Position 3 (red connector)

The brown is connected to Position 4 (blue connector)

The thicker brown is also connected to Position 4 (double tab) 

Many Thanks, Rod

[RobH]

The white wire from your overdrive loom needs to go to an ignition-switched  point.   The easiest is at the fuse box where there are already two white wires. Connect to the other side of that fuse if you can, where the three green wires are. 

The brown wire should be connected to either of the brown wires on the dummy regulator.  I think your position 5 should be connected to position 4 anyway (best to check!) , so you can probably use position 5 if there is a spare tag on that. 

[Napoleon]

Thank you very much Rob

Rod

[RobH]

Actually ignore that last bit that was brain fade, sorry.  5 is an earth on the real regulator. 

It is the two terminals on the left A and A1 which are connected together which is why the brown/white and brown/blue wires go there. That is where you should connect the  brown wire from the overdrive.

 

 

Edited September 21, 2023 by RobH

[Napoleon]

Thank you Rob, all understood, will connect it tomorrow.

Much appreciate your advice

Rod

[Napoleon]

Six months later, back working on the TR3A. All the overdrive wiring installed as per the kind advice received last Autumn, except for the connections to the two interlock switches. 

On the attached images, I have numbered the wires 1/2/3/4 - and the connections on the interlock switches A to H.

Which numbers to which letters please?   

Thank you, Rod

[RobH]

[Napoleon]

Thank you Rob, very much appreciated.

Rod