I'm putting a 12V in an older Ford pickup and was skimming over the wiring diagrams for the '95 Dodge truck.

What is purpose of the "Automatic Shutdown Relay"?

This is NOT the "Fuel Shutdown Relay" that controls the Fuel Shutdown solenoid.

The Automatic Shutdown Relay is located in the power distribution center and is energized by key on or start power and then it feeds power to the "generator" (assuming this is the alternator?) and pin 57 on the PCM. It is grounded by pin 51 on the PCM.

So does anyone know the purpose of this relay? I'm assuming I need to hook it up, but I just can't figure out what it's for.

Thanks

 

The ASD relay supplies B+ to the alternator field circuit when the computer supplies ground at pin 51. The computer supplies ground when it gets a reading from the crank sensor (it knows the engine is running). This prevents the alternator from getting field current until the engine starts. The computer also controls the ground on the field current to regulate the alternator. You could bypass all this computer nonsense by using an oil pressure switch to ground the ASD relay and using the voltage regulator that's already on the Ford.

 

On the 24 valve trucks it also is the source of power for the lift pump. It's just a fancy key on relay, you should not need it.

 

The NAME 'ASD' makes more sense in the context of a gasser engine where it supplies power to the ignition system. There are several situations which the computer shuts the engine down.

 

Excellent answers! That makes sense with the alternator and all...

I ended up using the dodge power dist. center, just cut everything out that wasn't necessary (about 80% of the wires) and wired the yellow-red to start power and the green-black wires to key-on/start, works like a champ!

I plan on wiring in a wait to start light and cruise control, so I labeled those wires

Now a couple more wiring questions:

What is the purpose of the knock sensor wire on the diesel?

And I'm not seeing a water in fuel light, is that just a "check engine" light deal?