MG Car Repair: solenoid, replacement solenoids, spade connectors

Question
QUESTION: hi, my 1975 mg midget wouldnt spark so i brought out a test lamp and i found out that on the solenoid there are 4 posts and the post that the white with green tracer wire that hooks to the positive side of the coil isnt getting 12 volts. do you think it is plugged into the wrong post? out of the 4 post the top two get 12 volts and the bottom two dont. the coil wire is hooked in the bottom right. i plugged it into one of the post that were getting 12 volts and it sparked perfectly. is the solenoid bad or is there something im missing? thanks
         david

ANSWER: Hi David,
There are two large threaded posts on the solenoid and two small flat spade connectors or two small threaded posts. One large post gets a plate that goes into the starter motor and the other large post gets the battery cable. On some solenoids the two small spade connectors were different sized so that the two small wires could not be mixed up. However I have seen replacement solenoids that they were the same size so here is how to test the two small connectors.
Take a jumper wire and connect it to the battery cable and just touch each of the two small posts one at a time and see which makes the starter engage. That is the post that gets the White w/brown tracer wire and the other post gets the white w/light green tracer wire. If you have a White w/red tracer wire instead of a white w/brown then you have a 76 not a 75.

The white w/brown tracer wire is activated by the starter relay and the white w/light green is activated by the solenoid itself and has no power except when the solenoid is active.

The coil should have two white w/light green wires on the (+) side and one is powered via the solenoid when the starter is engaged and the other is powered by the ignition switch via a resistor wire so that a full 12 v is applied to the coil during starting and 6 to 8 v by the ignition switch when the starter is released. This is because the coil is a 6v coil.
Howard

---------- FOLLOW-UP ----------

QUESTION: thank you i will try that, so do you know if there is supposed to be 12 volts on the bottom two spade post of the solenoid. are the bottom two suppose to not have power or is the solenoid messed up?

Answer
David, different solenoids place the spades in different locations so "Top, Bottom, Right or left" means nothing. If you will just do what I told you to do, you will know which terminal gets which wire. AFTER you do that you will know which terminal has power or is supplied power under what conditions if you just read what I told you to do.

The pin terminal that gets the White w/brown tracer wire will ONLY have 12v when the starter key is activated. The pin that gets the White w/light green tracer wire will receive 12v from the starter motor only when the starter solenoid is engaged. Neither small pin on the solenoid has any voltage when the solenoid is not activated.
Howard