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Transmission control switch M20.

Started by _m.mcarthur_ , Aug 10 2013 02:52 PM

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8 replies to this topic

#1 _m.mcarthur_

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Posted 10 August 2013 - 02:52 PM

There is a transmission control switch mounted to right hand lower side of the M 20 manual gearbox.
Can anyone tell me exactly what this switch does?
I managed to break the brass contact off so there is nothing to plug the wire onto.
Does it need this switch ?
I don't want to replace it if it doesn't need .
Any comments much appreciated .thanks.

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#2 _Bomber Watson_

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Posted 10 August 2013 - 03:07 PM

Reverse lights.

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#3 S pack

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Name:Dave
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Posted 10 August 2013 - 04:24 PM

Vacuum Advance Control System

The TCS switch (Transmission controlled Spark switch) is located on the underside of the 3/4 selector shaft in the gearbox side cover. The black wire that connects to this switch comes from the Cold Feed Switch mounted in the cylinder head, in turn the Cold Feed Switch wiring connects to the TCS Solenoid.

If all your other engine emission control equipment is as per factory and in operating order then without the TCS system operational you won't get any vacuum advance in 4th gear.

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#4 _m.mcarthur_

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Posted 10 August 2013 - 06:41 PM

thanks for this explanation, the cold feed switch in the head is not present nor is the VAC solenoid.
I would believe that the emission control system will not be operational on this basis.
AS a result is the performance in top gear impeared as a result of no vacuum?
Is it worth the effort to reinstate the components ?
what advantage would this have if any?
opinions much appreciated.
Thanks.

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#5 _Bomber Watson_

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Posted 10 August 2013 - 06:43 PM

If you have the dizzy vac hooked up to the mani as per pre pollution setups it wont affect anything and you will still have vac in top.

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#6 _m.mcarthur_

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Posted 10 August 2013 - 06:54 PM

Thanks Bomber, yes the vacuum is hooked up from dizzy to man-, the vac solenoid was not present when I bought the car new, but I replaced the engine complete along with head which did not have a cold feed switch in the head.
probably not worth worrying about would you think.
many thanks.

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#7 S pack

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Name:Dave
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Posted 10 August 2013 - 07:07 PM

Thanks Bomber, yes the vacuum is hooked up from dizzy to man-, the vac solenoid was not present when I bought the car new, but I replaced the engine complete along with head which did not have a cold feed switch in the head.
probably not worth worrying about would you think.
many thanks.

Yeah forget about it. Would only be an issue if they ever picked it is missing some or all of the anti pollution gear when doing a WOF or going for rego, if your car is not already registered.

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#8 yel327

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Posted 10 August 2013 - 09:49 PM

You shouldn't have vacuum advance pipe on a manual connected to the manifold, it should go to a ported vacuum port on the carby othrwise it'll get too much advance at idle and hence not idle properly.