Tomtr250 Posted January 12, 2018 Report Share Posted January 12, 2018 Im trying to sort out an O/D problem on my friends 4A, its fitted with a J type box, so far Ive checked all of the wiring and there is power everywhere there should be, the solenoid can be felt to click when the switch is operated but the O/D will not pull in mechanically, however, if I run the car and operate the solenoid direct from another battery, the O/D does pull in? Looking at the relay with a meter, I get 12 v into it and 12v out of it at W2 .......BUT! If I attach a test lamp .....its bright at C1 etc but very dim at W2 even though the meter reads 12v and also dim at the supply end on the switch My gut feeling is a bad earth somewhere which is where I will go next but and advice would be very welcome Many thanks Tom Quote Link to post Share on other sites
RogerH Posted January 12, 2018 Report Share Posted January 12, 2018 Hi Tom, check all the connectors. It sounds like heavy corrosion in one of the Lucar connectors. Roger Quote Link to post Share on other sites
Tomtr250 Posted January 12, 2018 Author Report Share Posted January 12, 2018 Hi Roger Thanks for that but everything is new, the car was fully restored last year, the O/D has worked intermittently, only just got round to looking at it Tom Quote Link to post Share on other sites
RobH Posted January 12, 2018 Report Share Posted January 12, 2018 (edited) Not sure about the tests you have done Tom. W2 goes to the interlock switches so a test lamp will be dim there because power has to come through the relay coil first. You need to do that test on C2 which is the terminal that drives the o/d solenoid. If the lamp is dim on C2 (with the o/d on) there is either something wrong with the connection as Roger says, or the relay contacts are not making properly. If its OK there, try the lamp on the solenoid end of the wire. Edited January 12, 2018 by RobH Quote Link to post Share on other sites
Tomtr250 Posted January 12, 2018 Author Report Share Posted January 12, 2018 Hi Rob C2 checks out ok with a bright light and the solenoid is clicking, there is continuity fron the relay to the solenoid Tom Quote Link to post Share on other sites
RobH Posted January 12, 2018 Report Share Posted January 12, 2018 (edited) A meter may show continuity but its no guarantee the connection can handle a high current (a meter only takes microamps). If you can measure what voltage gets to the solenoid end when the power is applied to it and with the solenoid in circuit it might tell you something about the connection. Is it the same as the voltage you applied direct from a battery ? If not then that is likely your problem. I suppose it could also be that the solenoid adjustment is marginal and just needs a wee bit more voltage to make it operate than the car wiring will allow. Have you checked the solenoid adjustment? (edited- of course the J doesn't need adjustment) Edited January 13, 2018 by RobH Quote Link to post Share on other sites
Tomtr250 Posted January 12, 2018 Author Report Share Posted January 12, 2018 Hi Rob W2 gives over 12v even though the test lamp is dim, I’ll try at the solenoid Tommorow see what it reads Tom Quote Link to post Share on other sites
RobH Posted January 12, 2018 Report Share Posted January 12, 2018 W2 is only the earthy side of the relay coil. There is no point in measuring that since the relay is operating OK. The terminal that feeds the solenoid is C2. This is the circuit in case you don't have it: Quote Link to post Share on other sites
peter clarke Posted January 13, 2018 Report Share Posted January 13, 2018 Throw the relay away as it is not required on a J type .......why complicate things. Relay prevents high current thru operating switch on A type (20amp) Quote Link to post Share on other sites
RobH Posted January 13, 2018 Report Share Posted January 13, 2018 Well Tom could do that Peter, though it sounds as though its not his car. It would involve some wiring changes to put the switches in series with the solenoid rather than to earth as at present (assuming the wiring is stock '4A.) Unless the relay is at fault, doing that its probably not going to solve the problem. Quote Link to post Share on other sites
Tomtr250 Posted January 15, 2018 Author Report Share Posted January 15, 2018 Rob/Peter Rewired it today by-passing the relay, still no joy, I’ve ordered a new solenoid ☹️ Tom Quote Link to post Share on other sites
Tomtr250 Posted January 23, 2018 Author Report Share Posted January 23, 2018 Hi all New solenoid fitted, rewired without relay ................. it works!!! Many thanks for the advice, really appreciated Tom Quote Link to post Share on other sites
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