Starter motor & solenoid re-assembly or connection issue?

[BigHW]

We have finally put the engine and gearbox back into our Mk 2 Stag and it is looking good. I took the starter motor off to clean and paint the body and also the solenoid. I thought I assembled the two together correctly. The electrical connections look correct; 12 volt large cable connected to the solenoid and the two small wires have different size spade connectors so they must be correct. The issue is when I turn on the ignition the starter motor engages and spins continuously immediately. It should, of course, wait until you turn the key further to switch on / engage the starter motor and as soon as you release the key the starter motor should be switched off. We have not touched the wiring inside the car so what have I done wrong? It has been a very frustrating afternoon! Thank you

[trunt]

Are you saying the engine cranks over when you turn the ignition on or does it just spin the starter without it engaging the engine?

The red white wire (large) is only live during cranking, but the small wire will get 6v or so when ignition is switched on (it comes from the coil and may even be 12v if it’s been modified for electronic ignition)
What is supposed to happen is that when you crank and the solenoid goes in 12v comes out on that small terminal to feed the coil, raising it from 6 to 12v for extra starting Spark.

a guess is that something has gone wrong internally, maybe the feed from the coil is trying to engage the solenoid. That’s a Long shot but try disconnecting the small one and see what happens.

[BigHW]

Thanks for your suggestions which I tried. Eventually identified that my buddy had badly marked up and then put the four wires back on the auto gearbox inhibitor switch incorrectly. This is why we had 12 volts on the red/white wire to the solenoid permanently when the ignition was switched on. Pleased we fathomed that issue without struggling to remove the starter motor & solenoid out to examine. Have a great day.

[wilf]

Good news, and good fault diagnosis.

[sujitroy]

learnt on the Stag not to do too many jobs at once especially with electrics.