Overdrive inhibitor switch

[Tim Murray]

I'm pretty darn certain that my overdrive inhibitor switch is finished;soI have gone and got a new one.

Now I havethree buts which perhaps you could help me with :-

But 1 ) exactly where is this switch ?

but 2) if its where I think it is [ on the l.h. side of the gear-lever extension }- how on earth does one get at it ?

I have removed the console and rubber gaiter, and can just about work out where it is, but cannot work out access. There is a small removeable panel in the l.h. of the tunnel, but that is about 6-8 inches too far forward. I can see the switch from underneath - just. Access is impossible. So looking for ideas please

but 3) concerned that I am looking at the reverse light switch not overdrive inhibitor. Can anyone clarify / confirm please.



Have Bl manual - but cannot find any help.

Many thanks

Tim

[Stagdad]

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O/d switch is on the top of the selector housing and the reverse switch is on the side ,don't know how to get at them as i replaced mine with the engine and box out of the car.

Cheers Steve

[alistair260661]

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got this?

[Tim Murray]

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Alistair - very many thanks for drawing and instructions

ermm., trouble is - mine doesn't look like this.

That bracket that looks like a downward pointer - just isn't there.

Icannot see or feelthe switch where shown,nor can I fine any wires that I might follow.

So still stuck :-)

thanks

Tim

[Stagdad]

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I think that pic is of an "A" type O/d Tim.The one i described is a "J" (later type)


Can't find a pic of it so i've arrowed where my switchis approx from memory (obviously that picture doesn't show any O/D).


Cheers Steve

[Stagdad]

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Found a bad pic of mine

[Tim Murray]

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Many thanks to Stagdad for the picy - very helpful indeed.

Now I really am struggling to imagine how I might change the switch, without at least dropping the g.box back a bit. There is just no clearance between the top of the box and the tunnel. Due to go out and about over Easter so will have to come back to this problem another day me-thinks.

Thanks again

Tim

[DJT]

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Tim,

If yours is on top as shown by Steve, then access is difficult as you surmise. If it is as per the diagram posted by Alistair, then you are in luck.

If you have the switch on the top of the box, ISTR that it is necessary to put a trolley jack under the gearbox crossmember and undo the 4 nylock nuts from underneath, allowing the rear of the 'box to drop. You should now just be able to reach the switch.

Are you certain the switch is goosed? I don't ever recall an overdrive or reversing light switch (same part) failing. The most common electrical failing is a break in the wires to the o/drive switch on the gearlever. These do fail quite regularly due to the constant movement of the lever.

The switch on the LH side of the'box is the reversing switch.

Dave

[Stagdad]

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DJT wrote:

Are you certain the switch is goosed? I don't ever recall an overdrive or reversing light switch (same part) failing. .

Dave

My reverxe light one was U/SDave and although the O/D one worked the terminals were wobbling about so i replaced them both as i had it out of the car.

Cheers Steve

[Tim Murray]

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Once again I must thank folks for continued interest, suggestions and ideas.

Here's where I am have got to:-

Examined the problem in close detail yesterday,

1) so can confirm that the switch is of the ' on the top ' type.

2) pleased to learn that one can gain access by dropping the box from rear. I'm guessing that one can win enough space without having to dismantle exhausts, which is some consolation.

3) you are correct about the gear lever wires, but the g.lever switch is also caput. It just fell apart in my hands.

4) For this weekend, I have hot-wired the o/d via a bodgetastic switch, which I have stuck to the side of the console. Just hope and pray that I don't forget to disengage. But I have also bodged a pretty big and bright warning light, gaffer taped to the steering column as a reminder. The o/d engages /disengages perfectly now, which is why I am confident that it is the original switches that are finished.

5) I don't like the sliding gear lever switch anyway, so plan to replace with something else anyway. I like the column mounted lever-switch as on a TR6 but think that may be a mod too far. Need to give this idea some thought

6) When I repair this for real, next week, I have the idea of introducing a relay, so that power can come straight from the fusebox, through the relay and into the o/d unit. Then the 2 in-line switches are only required to open/shut the relay. My idea is that this should be more reliable. I'll let you know how I get on.

Many thanks again, and happy Easter to all.

Tim

[Tim Murray]

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Evening all,

This repair that I was going to do before Easter, has, errr, dragged on a bit, as I've just finished it. But in the spirit of forum am now reporting back with news of how I got on.

I've one snippet that may be of great interest - please read on.

1) Managed to change the gearbox switch from inside the car. Yes, I's done it.

a) remove wood trim surrounding gearlever.

b) observe and remove the big grommet at front rh of the exposed area.

c) observe the switch through the vacated hole.

d)hacksaw from the grommet hole to the gearlever hole

e) bend the metal up

f) access the switch. It can be removed with a sharp cloutvia a large screwdriver. its not tight.

Be careful not to cut self on bent metal.

New switch goes in easy peasy, and can be tightened as much as needs be with a slim pair of plumbers pipe grips.

Getting the wires back on is a bit of a fiddle and requires patience.

g) bend metail back and reassemble.

Puritans may howl at the cutting of metal, but its a lot easier than dropping the gear box.

And now the valuable bit :-

While taking a celebratory cuppa tea, it dawned on me that the wires on the gearbox switch were not the same colour as those at the gearlever switch.

According to the circuit diagram they should be.

But the ding moment is - if they are NOT the same colour, its not the same piece of wire, ergo - THERE'S A JOINER.

The joiner is underneath, left hand side, just going up into the engine bay. Its a small loom, and a 5 pin plug and socket. When I removed the insulting tape, two wires just fell out thanks to corrosion, and yes one was the o/d circuit.

I've replaced the plug/socket with electricians connector block, c/w soldered terminals. A miserable task due to lack of space, and shortage of cable, But I've done it.

There's no way this plug would transmit electic with all the filth and corrosion, so if you think your overdrive is on the blink, strongly recommend examination of this joiner.

Hope it helps.

Tim

[pcoleman]

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changed my inhibitor switch about 6 weeks ago as overdrive was trying to engage in 2nd gear when giving it the beans, just managed to remove the switch from underneath with car on large trolley jack and axle stands at full tilt,the switch WAS knackered as open circuit all the time so well worth doing and no more problems (yet)

pete.c :shock: