68 charger not cranking at switch

68 charger not cranking at switch. Starts when I jump starter relay. Tried another starter relay, but still doesn't work. Does relay need grounded to firewall? It worked before and tight to firewall. Messed with neutral safety switch wires. Removed and jumped, but sure if I jumped correctly. Still doesn't hit at switch. Replaced ignition switch. Doesn't crank in any gear. Any ideas?

solenoid is on the starter motor


starter relay is on the firewall, or inner fender depending on the vehicle

If it's not 'starting' then it's in the ignition somewhere, and that can be a big problem to find.

If it's not 'cranking' then that is a different circuit.

Turn the key to 'start', hold there, wiggle the shifter to see if that is set correctly and maybe not aligned/adjusted correctly.

Edited. Not cranking

Don't throw parts at this sort of problem. It's a very simple circuit. With the car in park with the brake set pull the wire off the "G" terminal of the relay. Run a wire from the "G" terminal to ground. If it cranks with the key, the problem is the NSS, the wiring to the NSS, or the shifter out of adjustment. Very easy to track this down with a meter.

If it still doesn't crank, make sure you are getting 12v to the "I" terminal on the relay when the key is in the start position.

Center terminal on the neutral safety switch is the ground for the starter relay. The outer two terminals are for the back up light circuit.

What Jim said, either the "grn" terminal on the starter relay ain't being grounded somewhere from that terminal down to/thru the NSS on the side of the trans. Do Stumpys' trick of holding the ign switch to start & moving the shifter from park to 1 & back & see if it cranks. with the trans in park or neutral the middle terminal on the NSS switch should have continuity to the trans case. several connections in that wire from relay to trans that need to have continuity from end to end. If good there the yellow wire "ign" terminal at the starter relay should be hot when the key is held to crank (grab a helper,or wire in a test light that you can see from the dr seat). You can permanently ground the starter relay "grn with several inches of wire & it will crank in any gear, not a safety issue for us but just sayin.

It's a '68. If it's original it's got a single post.

Yup, 68 is single terminal only.

Easy things to try, is to hold the key in start position while running thru the shifter gears, that checks if misalignment in linkage is the problem,
Then the small wire on the firewall mounted started relay can get loose or dirty and cause trouble. ground that lug and see if it cranks.

Over time the socket that fits onto the NSS gets hard and doesn't seat correctly. What I have done in a pinch is to fill it w/ silicone and cram it on there...it works.
This is why I have a starter button wired to jump the terminals on the starter relay.

Grounded starter relay to battery neg, no crank. Then replaced starter relay with manual starter relay with no g terminal. No crank.

See if the yellow wire is hot when the key held to start. EDIT faster yet if you dont have a helper handy, jump fire to the male "ign" terminal on the relay (the one the yellow wire is on). MORE EDIT If no crank then seperate the bulkhead & check the brass terminal in each half for that circuit & if good there then work upstream or downstream from there for the open. grab your meter.

Maybe this will help
The I terminal requires a 12V signal from the ignition switch in the start position.

The G terminal requires a ground signal for the neutral safety / clutch switch or body.

Those two signals energize the relay and send 12v to the starter solenoid energizing it and engaging the starter motor

TJP, Hope you don't mind, I borrowed you excellent picture.

rave_12000,
It's a fairly simple circuit. Since you said it will crank by shorting the starter relay you have already eliminated the starter itself. Everyone here is saying the same thing. It's just a matter of procedure. It's always a plus to have a good test light or volt/ohm meter handy especially if you are working alone. It can get tricky trying to turn the key and fiddle with the starter relay at the same time.

No problem Shorthorse, And a big to you for taking it a it further.

If the OP can't fix it with the info provided, they'll need to find a "helper"

Is anything else working? Lights, radio, heater blower motor, etc.? You may have blown the fusable link.