Mopar Muscle Association UK

To be brief, the metal capillary wire from a temporary temp gauge I had wired up in the engine bay arced across the starter 'BAT' and 'SOL' terminals on the starter relay during a test fire. (Engine has run several times before then with no prior issues). I test fired the engine immediately after to make sure there was no damage to the starting circuit and the car fired right up.

Since then though the car will not crank no matter what I try. Initially I figured the starter relay was knackered so ordered a new one. No joy, then I spent a good amount of time tracing wires, doing continuity tests, voltage tests, and resistance tests which led me to the conclusion that the starter was knackered (rapid quick firing of the solenoid despite getting a healthy 12.9v to the starter)

After wrestling out the old starter (a new powermaster high torque starter) and seeing the arc damage on the brass contact plates inside I made the decision to buy a new starter, wrestled it into place, and...nada. The starter relay clicks once on the turn of the key and nothing else.

A few things I have discovered in my exploration though

I get continuity between the 'SOL' terminal and the starter body. It's going to ground - is this correct?
Upon cranking, voltage at the 'BAT' terminal drops from 12.9v to 0.0v - am I correct in assuming that's a short or possibly a knackered battery?

It's a bit of a head scratcher for sure and I've already had to cancel a rolling road sessions whilst I figure this issue out. Any help or advice that can help me get back and running would be greatly appreciated

Edit: For reference, the car is a 1970 Charger, 440, auto, with an AAW loom and MSD ignition

Unless it is a Race car (and they are often wired the same way!!!) The MAIN power for the Starter Motor is wired directly from the Battery.

Please see the attached diagram for the rest of the wiring.

Good luck.

That's how I have the starter wired up. The car was running before the short incident and nothing has been changed since but now the only sound I hear is the single click from the starter relay located on the firewall when the key is turned to the crank position.

The old trick (After you have absolutely confirmed the car is in NEUTRAL) is to get a screwdriver and Short out the BATT and SOL Terminals on the Starter Relay. The Motor should immediately crank. We have had to do that in the Fire up lanes a few times!!

Try directly earthing the connection on the solenoid that goes to the neutral safety switch to rule that out. Screwdriver across the bat and sol terminals and it should crank. If it doesn’t, your issue is narrowed down to the main lead to the starter, the starter itself and the engine earth.

Had this issue with a mates Dodge on Sunday. Same solution as Pete and Blue suggest. Fired straight up with ignition on and shorting the solenoid out. I also probed for voltage on the yellow wire which was good for ignition as the key was turned to full start position. Suspect a NSS issue. Had the same with my Roadrunner a few years back. Seems to be quite common.
A power probe is a really useful tool for this sort of issue.

I had a similar problem, it turned out to be the wire from the bulkhead connector to the starter solenoid as Blue suggested it may be.