wiring troubles

[Lang Inder]

The l16 in the 140j is ready to start up but i seem to have some problems with the wiring somewhere, basically you put the battery cables on and the starter starts up automatically, but isn't engaging. Disconnect the altanator put the cables back on and its fine, have dash lights etc. Have changed the altanator twice so don't think thats the problem anymore.

Ideas??

[torqued]

Just guessing but sounds like its not wired up correctly .

unplug your ignition switch. check wire voltage at that point.

This is 510 but you get the idea.

1970-1972-Datsun-510-Starting-and-Charging-System-Wiring-Diagram.jpg

[classicdat]

Have you checked the starter? If you had a wiring fault that falsed the starter I would have expected it to engage, somehow the starter solenoid is powering the starter motor without firing the pinion in. Have you got the cables going to the right side of the starter? Is your starter faulty, does it fire the pinion in when it is working normally? Not sure why Alternator would have anything to do with Starter, motor but not pinion, check starter wiring and compare to something else you have. (S110)

[Bartman]

Do you have the power supply hooked up to the correct terminal on the soleniod? Main power from the battery goes to the bolt which doesn't have the other wire coming off it which goes into the actual motor part of the starter unit.

[unlimitedpower]

My guess is a couple things. If your starter is firing but not engaging you either have a really shit starter (or faulty) or its getting a short from the signal wire. If you were getting the correct power down from the battery it would be engaging and turning engine over.
Now thats just weird. Like to know whats going on with that one. Could be a crook solenoid leaking power across.

You may also have a faulty key switch. After a couple million starts like datsuns have done copper traces can build up accros the inside of the switch leaving a short. Cranking while in on position or something like that.

[2 doors]

dont suppose among other things the starter is running backwards? either that or the throw out gear is stuck and wont throw out. reverse polarity could cause the starter solinoid to trip as well as causing starter to run backwards

[unlimitedpower]

Reverse polarity is also a very good way to cook your rectifier in your alternator so may pay to check that when you get it all up and running.

[chris_g1]

Have you got the black with a yellow trace wire on the starter