KM Posted June 7, 2021 Share Posted June 7, 2021 Its a Tr4A with negative earth. The overdrive has stopped working. The attached diagram is my wiring circuit. The relay appears to work. It has permanent 12v on the brown lead and switched 12v (ignition) on the white lead. In the attached diagram the white comes in at the top and the brown from the left. In 3rd or 4th, with ignition on and with the column switch in the on position, there is 12v at the switched relay output (the central pin - Yellow and Purple wire) for the solenoid but the solenoid doesn't move. If the solenoid is shorted (12v directly to the yellow/purple) it fires immediately. I have tested all the wires for shorts and breaks. The control column switch and the transmission switches work. The relay makes a definite click when being de-energised as opposed to being energised. So what I need help with: Is this a relay problem or something else? Quote Link to comment Share on other sites More sharing options...
glang Posted June 7, 2021 Share Posted June 7, 2021 Hi that doesnt add up! So with everything connected normally (nothing disconnected) you can measure 12v at the relay switched output but solenoid doesnt work. Then if you connect a 12v feed wire to the same relay output, in exactly the same place you measured the first time, the solenoid works? Quote Link to comment Share on other sites More sharing options...
RobPearce Posted June 7, 2021 Share Posted June 7, 2021 When you tested the solenoid by "shorting 12V directly", which end of the yellow/purple wire did you connect to 12V? Does it work if you connect from battery to the rivet on the relay rather than the wire? When you measured 12V at the relay middle contact, was the solenoid connected? If yes, did you measure on the relay terminal or the crimp on the wire? If not, with the wiring fully connected and the relay turned on, what voltage do you see at the middle contact? What about the brown contact? (Measure on the relay rivets!) From what you've told us, I'm suspecting a high impedance, either in a wire (you may not have the right equipment to measure that) or on a contact surface, either in the relay or one of the connectors. Before replacing the relay, you want to check that it's actually in there that you have a problem. The answers to my questions above may help determine that. Quote Link to comment Share on other sites More sharing options...
KM Posted June 7, 2021 Author Share Posted June 7, 2021 glang - yes Quote Link to comment Share on other sites More sharing options...
glang Posted June 7, 2021 Share Posted June 7, 2021 And you disconnected nothing to put the 12v test feed in, just touched it on the relay output terminal and the solenoid works? Quote Link to comment Share on other sites More sharing options...
KM Posted June 11, 2021 Author Share Posted June 11, 2021 Thanks for all the advice and suggestions. It was the relay at fault. I am still puzzled as to what was going on but the switched positive had 12v until there was a load, ie the solenoid, on it. Quote Link to comment Share on other sites More sharing options...
RobPearce Posted June 11, 2021 Share Posted June 11, 2021 3 hours ago, KM said: I am still puzzled as to what was going on but the switched positive had 12v until there was a load, ie the solenoid, on it. Dirty contact. It's very common. If you test without load, it looks like it works, but it's got a high resistance so when the load is present it doesn't. That's why glang and I both asked whether you'd disconnected the wire when testing. 1 Quote Link to comment Share on other sites More sharing options...
Guppy916 Posted August 9, 2021 Share Posted August 9, 2021 any updates guys Quote Link to comment Share on other sites More sharing options...
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