Crank no start - DodgeTalk : Dodge Car Forums, Dodge Truck Forums and Ram Forums
Thread Tools
post #1 of 5 Old 07-18-2019, 05:06 PM Thread Starter
Registered User
Join Date: Jul 2019
Posts: 2
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
(Thread Starter)
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
Jwhite0627 is offline  
Quote Quick Reply
Sponsored Links
post #2 of 5 Old 07-19-2019, 12:22 PM
Registered User
Join Date: Nov 2014
Location: Huntsville, TX
Posts: 659
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 111 Post(s)
I'm not that familiar with the modern engine controls and interlocks so this could be way off base. Many years ago I had an Oldsmobile with the same problem. Key on, fuel pump runs for about 3 seconds. When try to crank, nothing. I replaced fuel pump and ECM to no avail. Finally decided to just hot wire the pump to key on ignition. Car ran great for about 2 minutes and then spit a connecting rod out the side of the block. It turns out that there is an oil pressure interlock that kills the fuel pump if there is no oil pressure (the idiot light bulb was missing so no warning until massive valve clatter for about 2 seconds followed by grenading engine).

Could you have a weak or non-functional oil pump and the truck is trying to save itself?

J.T. Wooley

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
txwooley is offline  
post #3 of 5 Old 07-19-2019, 12:39 PM Thread Starter
Registered User
Join Date: Jul 2019
Posts: 2
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
(Thread Starter)
I dont think you're that far off, I do believe that there is something keeping the pcm from telling the pump to turn on. However it's why does it not tell it to, because every signal it needs to do so is there. It just doesnt send the signal during cranking.
I know the circuit itself (all the wires, connectors, etc) is good because for the 3 seconds the pump primes the system functions as it should. It's just upon cranking it doesnt send the signal.

Its definitely either the pcm or the tipm. I just dont know whatelse I can do to prove it one part or the other.

I've eliminated the pump itself, I get the same voltage readings at the pump connector with it plugged in it unplugged.

So the only thing left is why is there a 2volt drop after the prime. Has to either be internally in the tipm or pcm
Jwhite0627 is offline  
Sponsored Links
post #4 of 5 Old 07-23-2019, 08:23 PM
Registered User
super99ram's Avatar
Join Date: Jul 2006
Posts: 3
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Hi, recently I had an issue with my 1500 would runrof a bit and then shut off while driving. it would start back up after a 20 minute cool down. Found out the pcm was at fault and not much to do except change the pcm. Flagship one resolders and replaces parts known to fail in addition to resoldering the entire board. I have had this issue on my 99 ram as well as the 2006 charger. Both remedied for about 250 each issue. Hope it helps
super99ram is offline  
post #5 of 5 Old 07-24-2019, 12:06 AM
Registered User
Join Date: Nov 2009
Posts: 212
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 24 Post(s)
How about:

4. Fuel pump is failing internally.
guyonearth is offline  

Quick Reply

Register Now

In order to be able to use most of our features, you must first register.
Please enter your desired User Name, your Email Address and other required details in the form below.

User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
The registration process requires you to activate your membership by following a link in an E-Mail that will be sent to you immediately upon completing this form. You must enter a valid email address or you will not receive this activation code and you will NOT be registered. Your E-Mail address is NOT publicly available to anyone as policy.

AOL E-MAIL USERS: Please click HERE for important info pertaining to your e-mail address.

Email Address:


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
User Tag List

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page

Forum Jump

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

For the best viewing experience please update your browser to Google Chrome