Need Help! No start issue, bad ECM?

[brantcummins]

Alright, guys so it is a long story but I just finished rebuilding the engine on my truck and got it in and am trying to get it started. It is a 01 with a 6spd. I have an airdog 150 installed as well and many other engine parts. I have been cranking and cracking injector lines and fuel will come out but it won't start.

I did, however, hotwire the pump and got it to start and idle just fine as it should so I know my pump is good.. So, that narrows it down to something in the harness or CAN bus wiring. Dont know if maybe I have a bad ECM? I tested the pins on the ecm and all of my power and ground curcuits are good.

 

Looking for some advice and further diagnosis thanks!

 

[Mopar1973Man]

Does the wait to start light come on instantly? Does the light come on after a small delay?

 

If the wait to start light doesn't come on the ECM is not booted up and the VP44 and lift will not power up. 

[brantcummins]

The wait to start light will come on when I turn the key on and then go away but it never comes back on. I can hear the lift pump activate when I turn the key on. And if I bump the starter it will run. 

[Mopar1973Man]

ECM is booted if the light comes on instantly with the key.

 

So I'm wondering if you have an air leak in the fuel system and losing prime. It common to have suction side leaks that never drip or leak fuel. Bad crossover o-rings will make it hard starting. Banjo bolt at the bad of the head if the sealing washers fail it could cause starting issues. 

 

What's your fuel pressure during cranking? Does it rise to cranking pressure and pulse up and down normally or does it sit at zero for long period before jumping up?

 

Security feature might play a role and prevent starting that would be the PCM more so. Do you have a key fob? 

Edited August 18, 2018 by Mopar1973Man

[brantcummins]

When cranking it is about 10psi. It has 15 when the pump is running. I’m just wondering why it will start when I hot wire it but not when I plug it in? I put new feed tubes in with new o rings. Return line has new washers as well

[Mopar1973Man]

Key fob? (Security system locking out), ASD relay issues? (Check for error codes)

[brantcummins]

What is the ASD really and where is it at? The PSD I’m guessing?

 

I have 3 codes

P0123

P1693

P1694

 

i know P1693 is a companion code but I can’t get any codes off of the pcm it shows nothing

Edited August 18, 2018 by brantcummins

[AlpineRAM]

P0123 TPS A  high

P1694 No message from powertrain control module.

 

Sounds like a wiring issue to me, but check all the fuses first.. The diesels are a bit strange because there is the PCM like in the gassers and also the ECM on the engine. If they do not communicate correctly the VP44 will be told not to inject fuel. The "hotwire" test lets you start the engine without any involvement of ECM and PCM.

[Mopar1973Man]

Ah... 

 

PCM is not seeing any communication from the ECM. Double check the two connectors to the cowl. The CCD bus is in one of them. Remember PCM is the primary computer and the ECM is the companion module.

 

This will aid you in testing the APPS wiring. 

 

Edited August 18, 2018 by Mopar1973Man

[brantcummins]

My connection is good from the ECM to PCM. The pcm is working because when it runs all the gauges work. But obviously I have no throttle because the ecm isn’t connected. Which is why I probably got the apps code. I got a buddy that has an ecm I can borrow. Should I get it and try it? I just don’t know what to do. It ran fine before and never had issues

I can get all the data from the ecm off my scanner

Edited August 18, 2018 by brantcummins

[brantcummins]

So I got my harness out and opened up and this is that I found. I don’t know what the symbol means on the wiring diagram. But there was obvious open wires and on both the ecm and injection pump. It says it is the data link connection

 

[dripley]

Have that same thing in my spare harness. Got assume they are in all of them. I have not opened it at the VP to see whats there yet.

[brantcummins]

Went through the ecm harness and didn’t find nothing. Still won’t start

[AlpineRAM]

The wire strands are the shielding of the VP44 datalink to the ECM.

Needs to be there, needs to be connected to pin 3 according to diagram.

[Mopar1973Man]

Yeah on Dodge trucks its open on pin 3. It terminates at the ECM though. 

[brantcummins]

Yep 3 and 9 are open. I got a buddy that’s got an ecm and I’m gunna try it. Can’t get nothing to work so I’m thinking ecm. 

[Haggar]

That is a normal way to show a shielded pair.  With only one side going to ground. 

 

I'm not electrical, so my terminology may be a bit off, but the end not connected is "floated" and the other end of the shield is grounded.  This was to prevent electromagnetic interference on the wires.   

 

(if you ground both ends....well this can set up a problem that ground loops and sends your signals haywire....ask me how I know....) just for fun, sometime you do connect both ends to  ground though.....  I swear sparky's used the English language as a guide to setup their rules for electricity.  (the exceptions are almost as plentiful as the rules....  lol)

 

Hag

[AlpineRAM]

OK, sorry, should have said connected on pin3 ECM side.. As Mopar1973Man, brantcummins and Haggar correctly observed.

 

Have some experience with buggered shielding on slightly bigger wiring- mainly power bus on 50kW frequency controllers... do the shielding in an alternative way and you know where the term "sparky" comes from...