Crank no start
I have an 06 ram 1500 5.7L that has a crank no start condition. After some diagnosis, I came to the conclusion it's not getting fuel. So I turned my attention back to the fuel pump. I say "back" because I initially looked to it, but when I heard the pump prime at "key on", I went to check spark.
Anyways, so checked for pressure at Schrader valve. Has some but not what I'd like to see.
Long story short, I put a volt meter on the pump connector and I'm getting 12v at key on (when pump primes) and after 3 sec prime it drops to 10.5v, then finally when cranking it slowly drops to under 1 volt.
With a scanner on obd2, no codes, but looked for rpm signal. Confirmed pcm is receiving crank signal both with voltmeter and scanner.
I'm familiar with the 07 and up tipm fuel relay bypass, however it doesnt apply to this style tipm. So 1 question is, does anyone know a way to bypass it on this style tipm.
I would think that if the pump primes, that the relay works just fine? So then the problem should lie inside the pcm? Anyway to verify it is infact the pcm (without swapping a known good one, as it's been hard to find one to borrow)?
Any ideas would be appreciated.
Most diagrams and service manuals do not have documentation of this style tipm so it's been quite the project. I've narrow it down to 3 possible things.
1. Still a faulty crank sensor (though it sends some signal) however not likely
2.pcm receives signal and sends to tipm to send to fuel pump, but relay is bad in tipm so it never gets there. -unlikely imo because the pump primes with 12v
3.pcm receives crank signal and never tells tipm to turn pump on. (Most likely) but want to prove before throwing a part at it.
Maybe pcm controls the relay differently from different ignition switch positions?
Thanks in advance