Engine/Transmission (1998.5 - 2002) signals to and from vp - 44 TO ECM

[2-ND TIME]

Does anyone know what will cause the Datalink (-) fuel injector pump rectangular signal to flip, long rectangular wave to very short duration spike pulses to slightly longer duration pulses???? This seams to happen once every 3/4 of a second . Has anyone got any spects on the electronic signal requirments of the Bosch VP-44 pump ??For have been analizing them for some weeks and have a 1 volt ptp with alot of spiking in the signal for the Fuel injection pump sync Signal is this suposed to be a square wave??? Mine isn't For it has a spiked notch taken out. The low idle select is to me avery poor signal also. Any and all info will be much appreaciated and used for I'm determined to fix this ENGINE BUCKING . Was able to find out yesterday thjat there is a" BREAKOUT TOOL" for isolating the engine and Vp-44 from the rest of the componants others might want to use this info to get some problems fixed . It is interesting when you tell a dealer about this they say they have this and canuse it but don't tell you before hand. Then he tells me that I could still be fighting this in a YEARS TIME" NOT BLOODY LIKLY "three and a half years is mor than enough.

 

[Agades]

check the thread on Testing the VP 44



procedure on isolating the VP from all other sensors and ecm is in that thread

 

[2-ND TIME]

DATA

Think that I'am looking for more technical data???

 

[15w40]

The data link in our Rams is called a CAN Bus. CAN = Controller Area Network. This is a balanced (differential) 2-wire interface. To measure active highs and lows, you will need to probe across the two wires. Logic high is a signal between 1. 5 and 4. 1 volts. To get a lot of nerdy information on the CAN Bus protocols see this Bosch link: http://www.can.bosch.com/



Not many people have figured out our ECM programming. Cummins has kept it a secret to prevent unauthorized horsepower enhancements.

 

[2-ND TIME]

vp-44 troubles

Well I was looking at the information that was going back and forth in with the ECM and VP-44 and pin #1 had either a long pulse or for 250 milli sec flashed up the signal that I expect to see all the time. pin 2 was no better pin 7 has 14. 3v but has a large load imbeded in it. pin 4 goes from 11. 6v,to 6. 7v to 200+,300+milli volts by just a 1/16" of throttle movement. little wonder that the engine can't tell how much load it has on!!!!!!!!!:-{} :-{} Can you say mechinics that can't tell what they are doing!!!!!! Pin 8 fuel shut off signal is the best and that has a load impressed in it. I suspect that pins 1,2 move the two solinoids for fuel advance and start and end of the injection cycle. Iam surprised that the engine even runs at all . :-{}

 

[15w40]

Pins 1 & 2 on the VP44 are the CAN Bus data signal leads. The only way to look at these is to measure between them. If you try looking at pin 1 or pin 2 with respect to ground, you will not see anything that makes sense. The ECM interprets all of the sensor signals and APPS signal and turns them into a CAN Bus protocol for the VP44. Good luck trying to figure this out.



Pin 7 is the +12 (or +14 volt) signal from the VP44 relay that is on when the ignition is switched on. Pin 4 is the low idle select signal from the ECM that tells the VP44 the loud pedal not pressed.



What is it you are trying to measure?

 

[2-ND TIME]

Vp-44

That is a good idea forgot about that so will do that tomorrow night. and let you know the truck doesn't idle or run very well at all and tring to figure out why. :-{} Thanks will keep you posted on the interesting waveforms that come out of it .