Overdrive wiring fault diagnosis....

[Alex]

Can anyone talk me through the best way to test my overdrive wiring.
I know it worked when removed from my old car but its not working now.
How can I determine where the fault lies?

If I put the ignition on the green wires under the washer bottle are live but connected to the overdrive loom the switch is dead in 3rd gear.....and I assume 4th :)

Can anyone tell me what colour should be where?

Thanks,
Alex

[Jimmmy0_0]

Have you connected the car to box wires in the correct way around as it seams to be working back to front.?

James

[Alex]

Sorry James....how do you mean back to front?

Maybe I've not explained it very well :-/ If I put my meter on the cars loom I get power providing the ignition's on.If I test the gear lever switch again with the ignition on I get nothing, not even when in 3rd or 4th.

[AlanChatterton]

I think you got the 2 green wires under the bonnet the wrong way round..........

[Dave2000]

Just to expand on what Chat said, do you get power to the gearlever switch when it's in reverse?
If so, then the power's getting through (obviously!) but the inhibitor's kicking-in to say "No, you can't have overdrive in reverse" and thus doing its' job properly.
If this is the case, then the two green wires under the bonnet just need swapping round.
Hope this helps

[Alex]

No power to the switch ever.
The wires under the bonnet are definately correct as one has a brown stripe in it.

Its the rest of the wiring I'm questioning.

It appears that the greens go to the switch on the side,one piggy back's to the solenoid.
The switch on the top of the box goes straight to the lever.....I'm sure this is all wrong but need the correct order.......

Thanks
Alex

[piman]

Hello Alex,

forget the green and brown, that is for the reversing switch and has no part in the overdrive control.

I have a circuit for the 'A' type and all the colours from the relay are yellow. However, the colour code will still be the same group (i.e. yellow) for a 'J' type. For an 'A' type the control supply is a white (fed from ignition switch) and the relay power is brown which would not apply to a 'J' type as brown is permanently live..

My guess will be a green (Ignition switched fused supply), or maybe yellow\green to the 3rd\4th inhibitor switch then to the gearlever switch (yellow\yellow purple?) then to the overdrive solenoid.
The easiest check to determine the colour is check the fuses and see what you have there and work from that?

I hope that gives some clue. For some reason the workshop manual is not very good and only the occasional model page has a drawing.

Alec

[AlanChatterton]

Just realised, J type wiring!!

Okay, this is how it should be for a J type.

Two wires under the bonnet, one is ignitioned live, one is the feed to the reversing lights.

These 2 wires go to the reversing light switch, (on the side of the box) and when in reverse the circuit is complete.

The one with the ignitioned live has a piggy back off it to take power to the 3/4th isolator (top of the box) out of that to the switch on the gear lever, out of that to the solenoid, then from the solenoid to earth.

I'm guessing you've got the piggy back off the wrong side of the reversing light switch, which means you only get power to the overdrive in reverse, which then gets stopped by the isolator.

Hope this helps!

[Alex]

Mmm ok Alan I'll have to check...hopefully tomorrow :-/

Its not helped by most of my wires having replaced by incorrect colours.
So based on Alec' comments(thanks Alec) green is the live and green/brown is reverse,does it matter which connection on the reverse switch they are connected to?....then piggy back to top of box ,up to switch on lever and back to solenoid?..............

Am I right now? :B
I hate wiring!!!!!!!!

[AlanChatterton]

Yes, thats right.

Makes no different which side of the reversing light switch or isolator or solenoid you come off..... as long as the piggy back is off the live not the feed to the reversing lights.

Go live feed to isolator, to switch, to solenoid to earth and it'll work.

[piman]

Hello Alex\Alan,

from your posts Alan, the piggy back you refer to would likely be a two wire crimped to one terminal in which case your earlier diagnoses of the two green wires being crossed at the bulkhead is probably correct. I.e., the supply needs to connect to the doubled up wire. Which terminal on the reverse switch is irrelevant. Unless, of course the wiring has been 'repaired' at some time in the past?
Alex, I'd swap the wires as Alan suggested in an earlier post as a first option.

Alec

[Alex]

I think its all done, I now have power at the switch.

When the box was off obviously the wiring was disturbed,the green and green/brown went to the reverse switch but then the live went direct to the solenoid rather than from the gearlever switch via the top inhibitor switch.

I've not had a chance to try it yet but its certainly live now.

Thanks for the help.
Alex