Engine Swap, Now No Crank

[LostInTheSauce]

I've got a 2000 4.0, 5 speed. I swapped the engine with a 2004 4.0. Took all the sensors off the 2000 and put them on the 2004 so the original wiring harness could be used.

I'm getting no crank. Battery reads 12.5, starter reads 12.4, I haven't been able to turn the key with the multimeter on either, but will have a friend help me with that later today.

Fuses are good. Swapped relays and still nothing.

Bench tested the starter using this method

and it fired just fine.

I'm going to go back and check/clean all grounds.

Put a fuse in the #20 spot on the glove box fuse box to bypass the clutch, nothing doing.

Going to check the actuator pin, but the Jeep started fine before the engine swap so I don't think that's it.

I'm not too good with electrical and multimeters so this is all a bit confusing to me.

Also, the grille is still off, but that shouldn't stop it from cranking, right?

Anything obvious that I'm missing?

 

[CharlesHS]

You need to have a friend assist you to test for voltage at the lead on the starter solenoid when you turn the ignition to START. You have already bench tested the starters operation off the engine; so you need to jump the starter terminals with the starter attached to the engine to verify there is enough voltage to crank the engine over. IF the engine will not crank over with the starter on the engine; remove and check the battery cable clamps/battery terminals for oxidation and ensure the clamps are tight on the battery terminals. Then turn the ignition key to ON and jump the starter terminals to see if the engine will start.

 

[LostInTheSauce]

You need to have a friend assist you to test for voltage at the lead on the starter solenoid when you turn the ignition to START. You have already bench tested the starters operation off the engine; so you need to jump the starter terminals with the starter attached to the engine to verify there is enough voltage to crank the engine over. IF the engine will not crank over with the starter on the engine; remove and check the battery cable clamps/battery terminals for oxidation and ensure the clamps are tight on the battery terminals. Then turn the ignition key to ON and jump the starter terminals to see if the engine will start.

Thanks Charles. We ran an alligator clamp from the ignition terminal to the battery and were able to start it that way. Now to find what's causing this break.

 

[CharlesHS]

Thanks Charles. We ran an alligator clamp from the ignition terminal to the battery and were able to start it that way. Now to find what's causing this break.

Check the ignition switch harness terminals, wiring harness and test the ignition switch primary and secondary contacts voltage. The problem could be the switch and not the harness continuity to the starter solenoid.