Ashley Posted June 5, 2021 Report Share Posted June 5, 2021 My car is 1969 model with the A type overdrive fitted. All has been working well until yesterday when the overdrive started clicking in and out randomly. I carried out a small static investigation today, only to find that it had got worse. Thankfully I haven’t tried to move the car because at the moment as soon as the ignition switch is turned on the overdrive solenoid clicks in regardless of gear lever position. I have carried out a continuity test on the overdrive switch by disconnecting it under the dash and putting a multimeter on it. The switch is functioning correctly. With my limited electrical knowledge, I suspect a faulty relay, but welcome any other ideas. Does anyone know where the overdrive relay is situated? Quote Link to post Share on other sites
Mike C Posted June 5, 2021 Report Share Posted June 5, 2021 "clicks in regardless of gear lever position" - you need to check the wiring around the gear interlocks. Probably have to remove the tunnel to get a good look at it. Quote Link to post Share on other sites
Ashley Posted June 5, 2021 Author Report Share Posted June 5, 2021 Thanks for such a quick reply Mike, but I have just come in from testing the inhibitor circuit with a multi meter. I get a circuit in 2,3 and 4 gears only which means that all is functioning correctly and takes me back to the relay. I have located it next to the fuse box and have a spare 12 volt auto relay I had intended for the fuel pump. Does anyone know how the 85, 87, 86, 30 marked terminals from a model relay marry up to the C1, C2, W1, W2 terminals of the original? Quote Link to post Share on other sites
RogerH Posted June 5, 2021 Report Share Posted June 5, 2021 Hi Ashley, C1 - 12 Power in C2 - Power out to the solenoid W1 - 12v into the winding (either from the column switch or ignition) W2 - winding out (with to the column switch or the isolator switch) https://www.vehiclewiringproducts.co.uk/c-219-relays-flasher-units/p-642-12v-4-blade-type-b This is a modern relay. 85 - into the coil winding 86 - out of the coil winding 30 - 12v Power in 87 - power out to the solenoid. Roger Quote Link to post Share on other sites
Nigel Triumph Posted June 5, 2021 Report Share Posted June 5, 2021 The solenoid actuation is adjustable on the A type overdrive. When I had a similar problem some years ago, careful adjustment got it workng again. Nigel Quote Link to post Share on other sites
Ashley Posted June 7, 2021 Author Report Share Posted June 7, 2021 Thanks for your responses gents. It appears that the issue was with the relay, not bad after 52 years. However as it has been intermittent I can’t be sure until I have some more miles under my belt. For anyone who is interested, I got through a couple of relays with diodes in them because I put the fed to the relay coil the wrong way round. Eg I put W1 - 85 and W2 - 86. Apparently for relays without diodes it doesn’t matter, but if the relay has a diode 85 must be the earth. So the correct wiring for the overdrive relay is: C1 - 30 C2 - 87 W1 - 86 W2 - 85. Hope this helps anyone dealing with a similar problem in the future. Quote Link to post Share on other sites
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