Crank No Start

CumminNotRunnin

CumminNotRunnin

Internet Mechanic
Joined
May 7, 2007
Messages
1,090
Who has seen a crank no start on a 1999 Vp-44 and it was a bad PCM?

Ran through the test on Bluechip diesel, cut shut down solenoid power. Hooked power and ground straight to pump and truck start and ran.

Varying voltage on pin 4 and pin 8 of the connector. The only thing I couldn't test was the can-bus going to pump.

First swapped ECM still crank no start.

Swapped PCM then it fired right up and idled. My question what inputs go through the PCM and communicate to the ECM.

My only assumption is something on the CAN circuit was telling the truck no to run.

Just interested in some personal experiences as why. No faulty sensors or circuits.
 
bradley59dzl said:
I had one just happen to me. Never found out the actual issue though.
Click to expand...

I'm not one to throw parts it, but I had these parts laying around and tried them for diagnosis. Just like to know what is failing in the PCM to communicate with the ECM not to run.

Because with the plug hooked to the injection and alternative 12v and ground go to the pump it still would not run. So one of the circuits outside the fuel shutdown solenoid was telling this pump not to run.
 
Thats how this truck was also. The problem lied in the + and - Data link wires on this one. If I removed either or wire it would run.
 
You beat me to it....
Could also be AC voltage from the alternator that fried the PCM.

Ed
 
bradley59dzl said:
Truck I worked on had no codes and it wasnt a communication between vp and ecm has something to do with the PCM
Click to expand...

First off the PCM doesn't control the VP44 the ECM does. ECM is on the left side of the engine and PCM is on the passenger side firewall.

So here is the wiring for the ECM to the VP44...
ecm3.jpg


Then here is the diagnostics for the P1689 code.
http://articles.mopar1973man.com/2nd-generation-24v-dodge-cummins/59-obdii-error-codes/228-p1689-no-communication-between-ecm-and-vp44
 
Mopar1973Man said:
First off the PCM doesn't control the VP44 the ECM does. ECM is on the left side of the engine and PCM is on the passenger side firewall.

So here is the wiring for the ECM to the VP44...
ecm3.jpg


Then here is the diagnostics for the P1689 code.
http://articles.mopar1973man.com/2nd-generation-24v-dodge-cummins/59-obdii-error-codes/228-p1689-no-communication-between-ecm-and-vp44
Click to expand...

That is correct and the only that goes through the PCM that has any input on the ECM would be the APPS sensor.

That PCM on the truck I was working was causing the crank no start. Swapped it with a good used one and the truck fired right up.

That is what I don't get, because it should have no input to the VP--44
 
I also did not have any codes at all, other than codes related to swapping ECM and PCMs around.
 
Mopar1973Man said:
First off the PCM doesn't control the VP44 the ECM does. ECM is on the left side of the engine and PCM is on the passenger side firewall.

So here is the wiring for the ECM to the VP44...
ecm3.jpg


Then here is the diagnostics for the P1689 code.
http://articles.mopar1973man.com/2nd-generation-24v-dodge-cummins/59-obdii-error-codes/228-p1689-no-communication-between-ecm-and-vp44
Click to expand...

I know the difference between a PCM and ECM. I also realize the ECM controls the VP. So why would swapping a PCM make a truck run then? I'll also note again, that if I removed either of the data link wires it would run.,
 
Last edited:
CumminNotRunnin said:
That is correct and the only that goes through the PCM that has any input on the ECM would be the APPS sensor.

That PCM on the truck I was working was causing the crank no start. Swapped it with a good used one and the truck fired right up.

That is what I don't get, because it should have no input to the VP--44
Click to expand...

No one does. I have argued with numerous "Guru's" On this. lol
 
Mine had symptoms, that something on the can-bus circuit was telling the fpcm not to allow the truck to run. I had 12v and ground hooked up, truck would default to idle speed and run with no connector hooked up. Soon as you hooked up fpcm wiring all voltages and ground were good. Had .260 v on both low idle set and fuel injection sync. I had pin 5 clipped to make sure it had no power going to it.

The only thing left would be the can-bus correct?
 
CumminNotRunnin said:
Mine had symptoms, that something on the can-bus circuit was telling the fpcm not to allow the truck to run. I had 12v and ground hooked up, truck would default to idle speed and run with no connector hooked up. Soon as you hooked up fpcm wiring all voltages and ground were good. Had .260 v on both low idle set and fuel injection sync. I had pin 5 clipped to make sure it had no power going to it.

The only thing left would be the can-bus correct?
Click to expand...

Correct. Exact same thing I had.
 
PCM has the ASD (Auto Shut Down relay) which can disable the ECM through CCD Network signals.

2002-Dodge-Wiring-Pg1.jpg


Or another way is having the HighLine Central timer with security function which will also disable the ECM.

CCD-Network-Wiring.jpg


So there is a few ways external to disable the ECM from other modules. But rather rare to see. So if this is occuring I would consider the Alternator AC noise test and see if the alternator is truely killing the electronics. The AC volts should measure typically 0.01 to 0.02 VAC. High limit is 0.1 VAC anything over this is a fail!
 
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