Possessed overdrive.

[Cirrusdancer]

Hi,

1972 Mark 1 with an overdrive that has a mind of it's own. Doesn't matter whether the switch is in the 'In' or 'Out' position the overdrive happily does it's own thing, switching in or out as it pleases which is usually when I definitely don't want it to. The car is new to me so I don't know of any previous work or problems with the overdrive.

Before my mechanical man dives in to investigate are there any known/common problems that other forum members have experienced that could cause this bizarre behaviour ? Ideas on what to check for first ?

Thanks in advance.

[nib]

Sounds like it could be a short, quite problematic are the two wires that go through the gearstick and connect under the top of the gear knob,flick the top of the gear knob off and see if there's anything untowards + check where the wires go through the gearstick for chaffing, might be worth having the ignition on with the gear lever in 3rd or 4th with the o/d off and wiggling the wires to hear if the o/d comes on, if you flick the o/d on and off beforehand you will get an idea of the noise you are hearing out for.
Mark

[TR5convalescent]

I agree with Mark. I'd only add that if you are leaving the ignition on without the engine running to try this test you should disconnect the coil or you might fry it.

[StagJonno]

If you need to use the Stag before you get chance to sort the problem, suggest that you remove the fuse beforehand to save the annoyance (for Mk2 at least, the fuse box is under the bonnet located on the near side of the bulkhead. The overdrive fuse being closest to the nearside wing).

Jonno

[Cirrusdancer]

Thanks for the useful advice, I'll start with the wires from the switch.
Very useful advice about the fuse, I never thought of that.

John.

[Hughesy]

If its not electrical it maybe low gearbox oil level? Craig

[DJT]

ANG were about the first to offer this wiring: http://www.angclassiccarparts.co.uk/...m-triumph-stag