****UPDATE, FIXED!****
I pulled the main connection off the transmission and checked for voltage, there should be switched 12v on terminal 4 but there was none. I traced the wiring harness and a connector wasn't seated as well as I thought it had been.


Hi all, I'm working on my buddy's father's truck. He asked me to put a motor and trans in it. It's an 02 F150 and we put in a motor and trans from an 03 to avoid the spark plug problem. I got it all together and the first thing I noticed was the ignition keyswitch was not engaging the starter. I jumped power to the firewall mounted solenoid and got it to run. But the transmission is throwing 3 codes and the OD light is flashing.
In a Google search I found someone that had the exact same problem. Same 3 codes and the key does not fire off the starter. It was one of those sites where you ask an "expert" for advice. Well the expert told him he had a clogged catalytic converter. So needless to say there never was a resolution.

I did pull the body off the truck so that I could just lift out the old engine and trans together and then drop in the new(er) combo. So glad I did too, as everything was different. Exhaust manifolds, motor mounts, power steering pump, timing cover. This thing has been the gift that keeps giving. None of the wiring harnesses got stretched or damaged in the process to my knowledge. But it does seem to be an electrical problem.

Anyone ever run into this?

 

What spark plug problem? If you mean the one with the 2V Triton engines were there are fewer threads holding the plugs in, that didn’t necessarily go away in 2003.

That aside, it sounds like the transmission harness needs to be looked at again. If the starter isn’t lined up, it may be caught in a bad spot.

 

The truck is not sending momentary power to the firewall mounted solenoid. If I jump 12v to the small terminal on the solenoid the truck fires right up. It's like I'm trying to start the truck but it isn't in Park or Neutral.
Since I pulled the body, I had the harness in my hand and did not see any chaffing or burning/melting on it. I did see some info on a fuse box problem preventing 12v going to the trans, but I hadn't touched anything under the dash.

Yes I am referring to the blowing spark plugs out problem. 2003 engine, it was what the owner of the truck wanted. He had the plugs blow out of the original engine a couple times. Then he put in the 03 engine. Now we're putting in another one. The truck has about 400k miles on it, and is in surprisingly good shape.