Engine wont turn over.

[smallblock]

My 74 challenger always started fine until a month ago, now all the lights and radio work but there is absolutely nothing when I turn the key. I have power at the coil when turning the key and power at the starter relay when turning the key, both a little over 12 volts. I can jump the starter relay with a screwdriver and the car turns over. Battery is new and charged. Ive checked the neutral safety switch and its clean and plugged in. Ive tried putting the car in neutral and starting and still nothing. Ive checked for good grounds and broken wires and everything looks good. I ordered a new starter relay and put it on and still nothing. Im going nuts at this point. Anyone know of more checks I can do to try and narrow this down? Thanks.

[solarguy]

With the car in park, temporally ground the post on the starter relay that goes to the NSS.  If it cranks, the problem is at the NSS, (bad or not grounding)  or the wire to it.  You said you already checked power to the yellow when cranking?  Be careful doing this test as the car will start in gear so make sure you're in park, brake on. 

[smallblock]

If the NSS is bad wouldn't it start in neutral?

[burdar]

With the car in park, temporally ground the post on the starter relay that goes to the NSS.  If it cranks, the problem is at the NSS, (bad or not grounding)  or the wire to it.

   If grounding that post doesn't change anything, you have a starter relay problem.  Both are easy to replace.  Just have a drain pan handy when you remove the NSS. 

[smallblock]

I replaced the starter relay with a new one yesterday and nothing changed. Could have gotten a bad relay I guess.

[solarguy]

I replaced the starter relay with a new one yesterday and nothing changed. Could have gotten a bad relay I guess.

You could have but do the test above to rule out the NSS or the wire to it.  No, it will not start in neutral with an bad nss. 

[burdar]

It's also possible that you have an issue with the "rooster comb" inside the trans.  That's what rides on the NSS and moves when you change gears.

[smallblock]

Put a temporary ground wire on the starter relay and engine cranks over so it's the nss or wire. Shouldnt be to hard to fix now. Thanks for all the help again!

[solarguy]

Put a temporary ground wire on the starter relay and engine cranks over so it's the nss or wire. Shouldnt be to hard to fix now. Thanks for all the help again!

the shifter linkage could be out of adjustment and not allowing the grounding of the nss when in park or neutral. 

[HP2]

'74s have the seat belt interlock relay that will do this. Have you checked that system or bypassed that relay?

[burdar]

Good call. I completely missed the fact that its a 74.  I think there is a button on the control box that bypasses the system for a couple start cycles.