4.0 swap wont crank over

[70roadrunner]

I swapped a 4.0/m5od into my 84 BII using a complete explorer wiring harness, from headlights to tail lights, including the dash. the engine and wiring came from a 91 with an auto trans. the ecu and its harness came from a 91 with m5od.
the problem im having is the engine wont crank over(starter not getting signal)
if I jump the solenoid it cranks over and starts right up.
do I need to change the engine harness to the one from the manual trans? I have that engine(cracked heads)
I really want everything to be just like the factory did it, no spliced or jumped wires

 

[RonD]

There is a safety switch(NSS-neutral safely switch) to prevent starter motor from turning if trans is in gear.
On a manual trans that switch is on the clutch pedal.
Clutch pedal needs to be down to allow power to pass to the starter solenoid.

Power path looks like this:
Battery------key switch------NSS------starter solenoid

On an automatic it is on the transmission, the Park/Neutral switch, often reverse lights are on the same switch
If you have automatic's wiring then there should be an unused connector that would run from the back of the engine down to drivers side of trans area, where the shifter would be.

You can put a jumper wire in that connector to by pass the NSS switch, or wire up a clutch switch to that connector, it is just a 12v in/12v out switch, like a brake light switch.
It is an important safety feature, up to you, but whatever you do make sure it is weather proof, nothing worse that a no start in bad weather

 

[4.0B2]

find your igntion wire from your key.... run a jumper to the little post on the solenoid on the fenderwell, then try to crack it. Report back with what happens.

 

[70roadrunner]

I have the dash from the manual trans, and have the clutch switch installed. I know im going to need to change the harness eventually, to have backup lights, and for the 4wd lights functional, but I didn't keep that harness from the donor.
when I turn the key, I can hear clicking, but no crank. when I jump from 12v+ to the small stud on solenoid, it cranks right up.

 

[Mudhound]

Try "continuity testing" the small wire for the solenoid. I had had the wire be bad on a couple of trucks.Why, IDK. Everything else functioning, so far, 70RoadRunner?

 

[70roadrunner]

yes, all is working. and it is a known good harness, I drove both explorers that I stripped for parts. I am positive that it is the start safety system. just not sure if its the clutch switch or the auto trans wiring. gonna do more testing

 

[70roadrunner]

figured it out today. have to push the clutch and jump the neutral safety switch wires. now I need to find the correct wiring harness for the 4.0/m5od/1354m combo!