Hello all so I have been doing a lot of reading and trouble shooting, still no solutions. My truck is defueling itself at 1900 rpm then comes back to 1900rpm  sometimes even revs up at 1900 no idea why not throwing any codes . My sensors are buzzing all over the place reading high . Here is what I’ve done. Checked vss and neutral ground,New cam sensor , disconnected pcm to just run on Ecm  still problem is there . Then I tested my map sensor with ohms to ecm checks out fine  checked apps checks out fine .  I’m now thinking ground problem I checked them all and double checked. I was just messing around with ohms and tested my 5v on map to  my double connector , the one that splits to fuse box and pcm.  I got a weird resistance of .5 from map 5v pin to a solid orange wire in the white locking double connector. I then traced that back to the ecm pin #46 witch from your wiring diagram is the crank sensor sending wire. The only time I get this reading is with the ecm wiring plugged into the ecm, when unplugged I have no ohms at all ? I then thought I would check my oil sending unit beings it shares a 5v wire with map . I do not have a oil sending unit it would appear ... there is a sensor below the ecm but it only has one wire gry/Black I will try to attach pictures it goes to pin#26??? Witch makes no sense because that is the pto pin according to your schematics ?? And on top of it pin # 6 which is where the oil pressure sending wire should go is empty ? Why would this be? I am about to buy a new engine harness and ecm  I just don’t want to spend the money if it is not the problem?  I’m sure I am missing more but just can’t remember at this point . I am in great need of everyone’s expertise!  And I just wanted to say I am very grateful for all of the info everyone has contributed to this site wouldn’t have got this far without it. oh and fuel pressure is good never drops below 11

@Fummins24v  have you tried unplugging the pcm? If you unplug the pcm and it still acts like this then I'd say it is bad. The Cummins dealers agree bound by the EPA. Problem is some people don't know it. Soon as you start talking about passenger vehicles ears go up and doors slam shut. It's why I'm currently deep in thought about an Insite setup. Pull a couple of these irons outta the fire first.

I got the same reaction when I wanted them to reprogram my ECM. Also got the same treatment from Dodge dealer too!

Like I said before I'm not knowledgable on the electrical troubleshooting but at this point Fummins 24V, I would install a new Timbo apps getting rid of the factory Apps. you will need it for reliability anyway since its much better/ smoother Apps it kind of goes hand in hand with a new VP.

 

My factory Apps had a dead spot, did not throw any codes, but the 7-8 thousand dollar Snap On showed slight dead spot on the screen when testing. Had a Timbo under the seat and now runs perfect.

I'm not saying Jag1 is wrong but 1850 rpms is a special number for us swap guys. Have you contacted Bob Wagner? That dude is the man when it comes to ecm's.

 

I had to relocate my apps because I needed the space where it lived for my ac compressor. I bought a Williams pedal with tps (and then another tps off eBay because the Williams one didn't have the idle validation circuitry) for under $60 and now my tps lives in the cab with me where it belongs. Every piece of heavy equipment, bus, tow truck I've ever seen has the tps inside and I gotta believe there's a reason.

Edited December 17, 20177 yr by Scottfunk

I always figured the moved them to save money. No more bellcrank assembly or throttle cable. With what dodge sells the for they saved a pretty penny on every unit.

I gotta believe it's one of those things Chrysler did to make things difficult...er Dodge I mean. Just like "special" ecm's and cad's. I mean seriously, center axle disconnect? Every other manufacturer is using hubs and Chrysler makes Spicer manufacture special cad's just for them. If it wasn't for the fact that the sensor in the cad works great with my Yukon's push button transfer case I'd write them a nasty letter. 

5 hours ago, Scottfunk said:

I mean seriously, center axle disconnect?

When  I first saw it I was like what a dambas. that made that happen. I would love to have hubs and serviceable bearings like old days as I only use it maybe hand full of times a year, why all this unnecessary wear. Plus a weak link and geometry of the whole axle .  

On 12/16/2017 at 11:07 PM, Scottfunk said:

@Fummins24v  have you tried unplugging the pcm? If you unplug the pcm and it still acts like this then I'd say it is bad. The Cummins dealers agree bound by the EPA. Problem is some people don't know it. Soon as you start talking about passenger vehicles ears go up and doors slam shut. It's why I'm currently deep in thought about an Insite setup. Pull a couple of these irons outta the fire first.

I have unplugged the pcm and yes it still acts up. I thought that this test eliminated the pcm? I thought that the pcm was not really needed? Just have it to pull codes? Am I wrong on this?

On 12/17/2017 at 1:07 AM, Scottfunk said:

@Fummins24v

The PCM needs to see ground on pin 6 in order to tell the ECM that it can rev past 1800

Also the PCM needs the communication wires hooked up from PCM to ECM. Look at the wiring diagram that is in my write up

Edited December 18, 20177 yr by mossyoak71
Word

1 hour ago, Fummins24v said:

I have unplugged the pcm and yes it still acts up. I thought that this test eliminated the pcm? I thought that the pcm was not really needed? Just have it to pull codes? Am I wrong on this?

Yeah you're gonna want to find a comfy spot for the pcm. In an automatic application the ecm needs to see the communication with the pcm to function properly. It has to stay, I'm sorry. I didn't like it either but there's no way around it. Is your ecm also an auto? 

1 hour ago, Scottfunk said:

Yeah you're gonna want to find a comfy spot for the pcm. In an automatic application the ecm needs to see the communication with the pcm to function properly. It has to stay, I'm sorry. I didn't like it either but there's no way around it. Is your ecm also an auto? 

Yes ecm is an Auto .i have pcm in a real good spot behind battery on driver side fender out of the elements. I noticed my pcm is a Motorola brand  definitely not stock . But anyway I guess I will go ahead and get a new pcm . I don’t see any other option.

Per your own words you stated that you only had these wires hooked up 

Quote:

i checked my pcm again I believe these pins are all that are needed to work?

pin# 31 32 grounded

pin#22 constant 12v

pin#2 12v key on power

pin#6 grounded

 You need to open the schematic that I'm sharing cause you don't have enough wires hooked up.i don't think you need a PCM. You only have 4 wires hooked to your PCM, you need 8 hooked up

24V PCM Schematic.pdf

I wanna say they're all Motorola. I got mine from a place called Diaz salvage parts out of Hillsboro Texas. Nice guys. Find them on eBay and shoot them an offer, they're reasonable. Unless there's an auto parts store close enough to limp down to and borrow an on a scanner. Maybe it'll tell you something. You'll have to do the full wiring job for that. I put my new obd connector in the center console with my tow/haul and 6th cancel.

On 12/18/2017 at 12:31 PM, mossyoak71 said:

Per your own words you stated that you only had these wires hooked up 

Quote:

i checked my pcm again I believe these pins are all that are needed to work?

pin# 31 32 grounded

pin#22 constant 12v

pin#2 12v key on power

pin#6 grounded

 You need to open the schematic that I'm sharing cause you don't have enough wires hooked up.i don't think you need a PCM. You only have 4 wires hooked to your PCM, you need 8 hooked up

24V PCM Schematic.pdf

Could you please try posting this again it will not open.

On 12/18/2017 at 12:31 PM, mossyoak71 said:

Per your own words you stated that you only had these wires hooked up 

Quote:

i checked my pcm again I believe these pins are all that are needed to work?

pin# 31 32 grounded

pin#22 constant 12v

pin#2 12v key on power

pin#6 grounded

 You need to open the schematic that I'm sharing cause you don't have enough wires hooked up.i don't think you need a PCM. You only have 4 wires hooked to your PCM, you need 8 hooked up

24V PCM Schematic.pdf

Never mind I got it to open on your thread thank you.

So did you figure it out, and if so what was it?

So what was your issue? Did you get it fixed??

The short story it was the vp44

 

Ok all sorry it took so long... but yes finally got it figured out. It took entirely to long just wanted to thank you all for your input and help. So after all the wireing checks hours on the ohms meter . I ruled out all wireing then everything else pcm Ecm  "I now have a spare Ecm and pcm if anyone's interested "  apps  cps I'm sure I'm missing others . I then did not wire test to vp44 still same defuiling. But I  couldn't think of anything else so I took the 3 month old bd 100 horse vp44 off and sent it in. Took them a week until they finally tested it they said it was good. I couldn't believe it so after a lot of bs back and forth they tested it again still said it was good but they said they would change the electronics on it for me just to make sure . Was very thankful for that other than I had to wait a MONTH until I got it back . And still didn't know if it would fix it.. well it did couldn't be happier runs like a top!  The injection shop couldn't believe it  when I called them to let them know that was the problem. Just hope it doesn't happen again. But next time I'll know right what it is . Just because your trucks not throwing codes doesn't mean the vp44 isn't Dying.

 

 

special thanks to moparman mans wiring schematics ?

9 hours ago, Fummins24v said:

Just because your trucks not throwing codes doesn't mean the vp44 isn't Dying.

 

Test your alternator for excessive AC noise. 99% of electronics failures are from excessive AC noise. 

Thank you Moparman I did during my initial quest for my problem. Tested good

Great news & I hope that cummins keeps purring like a pissed off kitty. 

 

L8tr

D