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Bobalos

Communication issues (& more)

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To start I have a 99, 2500, Auto, 2x4, 211,000, Lift pump in tank with Relay, 275 HP Bosch Injectors.

 

I am the second owner & got the truck in 2001, IIRC it has 15,000 on it. 

 

To make a long story short, I just finished doing a bunch of things I have been putting off for too long now.

Recently replaced (in order of installation):

Vacuum pump (http://www.fixinrams.com/)

PS Pump (https://www.genosgarage.com/) & Hoses (https://ormebrothers.com/).

Brand new Bosch 275 HP Injectors (Had Edge Jammer Stage 1's & wanted to see the difference)

 

ECM from https://carcomputerexchange.com/    (Lift pump was not turning on reliably & WTS light was acting all wonky)

Fuel Filter housing for 00-02 Cummins https://www.genosgarage.com/product/dodge-ram-cummins-replacement-fuel-filter-cannister-gg-fc98599/360  I was trying to troubleshoot the lift pump driver issue in ECM & Manged to crack the 99 Housing, so $180 later here I am....  

 

VP44 from https://www.bluechipdiesel.com/ (This is the second VP44 I have put onto the truck, the first very early in life, due to dead Lift pump)

 

So here is the deal.  As I mentioned Ive owned this truck pretty much its entire life & have put just about every mile on it.  I had the vacuum pump, PS pump & injectors put into it by a local Dodge shop, because I did not have the time to take care of it.  no issues/worries with that.

 

off & on for the last year or so I was having issues with the ECM turning the lift pump on.  I dug into it a bit & called the folks @ Blue Chip & Doug suggested that I just run the lift pump off of the Wiper circuit (as its hot during "run", but not "start").  while that worked fine (the truck would start & run every time), once of the side effects was that I was getting a P0230 code.  I called Blue Chip  back & he said that is because I did not have a load on the ECM (because the lift pump was disconnected) & that I should just "stick a fan on it to blow across the Inj pump" so that the ECM would see the load.  I didn't like that idea, so I wired another relay on that output (the exact same relay that I am using for the lift pump) & much to my surprise that did not resolve the issue. 

 

I did a bit of research & called 6 or 7 ECM sources & found that car computer exchange seemed to be knowledgeable about the Cummins specific issues & had a good answer to each of my questions (Im a Manufacturing Engineer for a company that produces devices that measure air pollution).  They were waiting on cores & said if I return mine I would get it quicker than if I waited to order one & then send my core back later.  So I did that.

 

I replaced the ECM & fuel filter housing @ one time & rewired the Lift pump back to the ECM where it should be.  every few years I check all of my grounds to make sure that there is no corrosion (like we get any weather in San Diego, right...............) & that everything looks ok.  I purged all of the air out & fired up the truck & it fired up after a little cranking.  HOWEVER......... the CEL came back on again. I hooked up the scan tool, cleared it & fired it back up again.  no more CEL.  Yes I did something stupid............. I did not read the code(s) I just cleared it/them. 

 

I replaced the Injection pump & when I went to fire it up, I found the batteries were on their way out (slow cranking & no fire).  they were 5 years old so I replaced them.  Hit the key with the new batteries & it cranked over great & fired right up.  HOWEVER the CEL is back on again. 

 

I broke out the $10 China Freight scanner & it came back with "there are no codes" (yes the CEL is on)  This is not the first time this has happened.  So I broke out the OTC Genisys, & the freaken thing wont talk with the stupid truck.  This is not the first time this has happened over the last 8 or 9 years.  Ive had this issue off & on for a while.  Ive not cared because the truck has worked fine & not had any CEL's so why would I care (paying for that now..............). 

Here is where it gets weird.  If I use the HF scanner & force it to clear the CEL it will do it.  if I ask the OTC to clear the CEL, it will not.  neither of which will "get data from the truck".   the CEL comes back on just about every time I try to start the truck.  Ive cleared & started it 20 or 25 times since I replaced the Inj pump & most of the time the CEL comes back on.  I have tried a few things. like checking connections & Grounds & other such things to figure it out, clear the CEL & fired it up & it comes back on........

 

MORE....................

 

So........ the questions.......

I have a factory manual & have dug into the schematics & see that there appear to be 2 Comm buses.  once is the CCD & the other is the SCI. 

I have read a bunch of stuff on this site as well other places, but am kind of confused about how this works & what does what. 

 

as much as anything Im trying to learn with these questions, not to just fix my problem, so bear with me. 

 

I get that the CCD talks between the ECM, Timer, Dash, PCM, etc to transfer information from one place to the next.  it is also present on the ALDL so I would assume that a "scanner" can talk on the buss as well to get data out. 

 

It appears that the ECM & PCM are connected to the ALDL on pins 6, 7 & 14.  Its interesting to me that there is a single transmit line shared between both computers, but they each have separate receive lines. 

 

SO............... When I hook up my scan tool cheap *** scan tool what is it talking with?  the ECM?  through the SCI lines or the CCD

 When Im using my OTC & turning on & off the AC Clutch, Trans Solenoids, lift pump, etc.  what buss is it using? 

When there is a code that the trans is not working correctly, where is that coming from?  is the scan tool talking with the ECM via the SCI & its getting the codes from the PCM through the CCD?  How the heck does this work.........

 

Shoot........... I didn't want everything in one HUGE post............

So, Specifically to this problem.

How do I go about troubleshooting my communication issue?  I took the OTC & plugged it into my wifes Mercury & it allows me to see everything & do everything, its working correctly. 

I have had issues with the Truck talking to scanners before, but Ive also had it work just fine & allow me to turn on the trans stuff & to datalog ECM & PCM stuff & watch the APPS voltage go up & down & everything you would think it should be able to do. so I know that it has worked before. 

IMO, I need to get the scanner working before I can figure out why the CEL is on.  I suppose I could assume that its the same P0230 code, but I dont want to assume anything........... 

thanks folks.
Bob

 

Edited by Bobalos

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Your communication problems are between the VP44 and the ECM.

 

You need to to do the ohm test on the wiring to verify there is 0 ohm from end to end. Then infinite ohm from open sockets to ground. Power issues can produce P1689 codes too but typically the truck doesn't start or run but does set the error code.  

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The truck seems to be running fine, so Im guessing that its the same P0230 code that I was getting before, but I wont know that until I get the ECM to start talking to the scan tool.  

 

thanks for the information, I will dig into it this evening when I get home.  

Any thoughts about writing up something in detail about communications & what is transmitted over what buses & what talks to what in what manner?  I read the article you wrote about the different baud rates & priorities of what is transmitted, & Im assuming that is over the CCD back & forth between modules, but did not want to make an assumption............... 

 

thanks again

Bob

 

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3 buses

 

SCI

CCD

J1939

 

SCI: is used for troubleshooting and talking from the obd plug to the ecm and pcm.  This is nothing more than a obd compliance bus in my mind.  

 

 

CCD: this is the major bus for the computers talking to each other, other than the vp44.  All data between the abs, pcm, ecm, ctm, cluster, overhead use the CCD bus to transmit info.  all sensor data is on this bus all needed calculations are on this bus, fueling and timing commands are on this bus etc.  this bus is the heart of the 2nd gen truck.  

 

 

j1939: is used for talking between the ecm and vp44.fueling and timing commands and answers are on this bus.  all engine sensor data is on this bus, some calculations are on this bus, others are not.  Example 98-2000 trucks have a load calc, but it is not accurate where as 01-02 trucks have actual engine load.  

 

 

The 2nd gen vp44 trucks are a mismatch of garbage to make things work while keeping the government happy with their regulations.   There are a lot of bandaids in the system to "make things work" 

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I performed the DTC P1689: No com between ECM & Inj Pump procedure & it all passed all of the tests.

 

the strange thing......... the first thing I did was to hook up my OTC Genisys scanner & it connected right up & allowed me to do everything I wanted it to do............  :(.  I hate it when things "fix themselves".  In my  experience things dont just fix themselves.

 

FWIW, this is the order of what I did:

Scanned: P1694

Cleared code

Cycled power, scanned: no codes

Cycled power, scanned: no codes

Cycled power, CEL ON. scanned: P1694

Performed P1694 test, everything was perfect. 

     continuity tests: <1 Ohm,

     Power tests: 12.5V (Brand new batteries) 

     Insulation tests: Infinite

 

(NOTE: Wait To Start light is still inconsistent.  sometimes it comes on as soon as the key is on & the dash lights come on & sometimes it waits for all of the lights to go out & then the WTS light comes on........  )

 

Turned on Ign: CEL On

with OTC, there are 3 tests I can run that takes 3 different dongles on the cable:

     Engine: Cummins ("no codes present") 

     Engine: OBD II ("no codes present")

     Engine: JTEC ("P1689 code present")

Cleared P1689

Started truck: No CEL

Started truck: No CEL

Started truck: No CEL

Started truck: No CEL

 

it was >8:00PM so I figured I would go in & work on it the next day.  The Scanner connected & worked perfectly every time I tried to talk with it.......  

 

Came into work this morning............ no CEL, truck ran perfectly.........  

I will check everything again when I get home tonight.........   Im frustrated with this thing.....  

 

I know there is no clear issue to work on, but I feel that there is still something going on. If anyone has any more suggestions, I would appreciate it. 

 

thanks folks.

Bob

 

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7 minutes ago, Bobalos said:

(NOTE: Wait To Start light is still inconsistent.  sometimes it comes on as soon as the key is on & the dash lights come on & sometimes it waits for all of the lights to go out & then the WTS light comes on........  )

 

All other error codes go out the window if there is a Wait To Start issue this points to bad memory on the ECM and could be self creating the error because of booting issues. Till the wait to start issue is resolved your chasing ghosts...

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one thing that is still confusing to me is this, My OTC has what appear to be 3 scan modes (Cummins, OBDII & JTEC).  Which one talks over which bus' & to which computers?  

 

 

 

21 hours ago, Me78569 said:

SCI: is used for troubleshooting and talking from the obd plug to the ecm and pcm.  This is nothing more than a obd compliance bus in my mind.  (OBDII mode?)

 

CCD: this is the major bus for the computers talking to each other, other than the vp44.  All data between the abs, pcm, ecm, ctm, cluster, overhead use the CCD bus to transmit info.  all sensor data is on this bus all needed calculations are on this bus, fueling and timing commands are on this bus etc.  this bus is the heart of the 2nd gen truck.  (accessible through small triangular connector above Inj pump??)

 

j1939: is used for talking between the ecm and vp44.fueling and timing commands and answers are on this bus.  all engine sensor data is on this bus, some calculations are on this bus, others are not.  Example 98-2000 trucks have a load calc, but it is not accurate where as 01-02 trucks have actual engine load.  (JTEC mode?)

 

3 minutes ago, Mopar1973Man said:

 

All other error codes go out the window if there is a Wait To Start issue this points to bad memory on the ECM and could be self creating the error because of booting issues. Till the wait to start issue is resolved your chasing ghosts...

 

If I take the test procedure I performed last night explicitly the ECM is "bad".  would you agree with that & this is where I need to start?  I had planned on contacting the folks that "re-manufactured" it & ask them exactly what they found was wrong & what they did to fix it.  I have a feeling though............ that Im not going to get answers that satisfy me.  

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Good bet. If the wait to start light doesn't come on the ECM is basically brain dead you can attempt to start the truck it will not start at all till that wait to start light does come on. Now the software is loaded. Being its having issues loading the software the other codes could be caused by bad data or software on the ECM.

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The delay WTS light is the single most damming piece of evidence on a vp44 truck.   If you have a delayed WTS then you have a ECM that is not booting.  

 

cummins is j1939 obd is sci and jtec apepras to be for gassers

 

http://buy1.snapon.com/products/diagnostics/downloads/manuals/DomesticVCS(EAZ0025B01CRevB)/07 ChryslerTesting.pdf

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thanks, I will call them today & see what they have to say.  the guy I talked with initially seemed pretty knowledgeable.

 

thanks folks.

Bob

 

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I figured I would post a quick update.  I called the ECM company & talked with their "tech support" guy & came away from the conversation MUCH less confident than when I called them the first time.

 

He gave me a lot of "we always do, we 100% test, the techs bench test every system, etc, etc)".  then when I asked if he had a report about what was done & more importantly what was not done, he said that he did not have such a thing.  then the "always do"; turned into "when necessary". 

needless to say, I sent it back & told him that I would call him on Monday (tomorrow) & I wanted a detailed report on what was & was not tested.  What was & was not found & what was & was not replaced. 

 

thanks for all of the help folks.

Bob

 

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update to this:

 

last week I went through EVERY ground I could find in the engine compartment & cleaned them & made sure that the terminals were in good shape & there was no corrosion (there was none). 

 

I sent the ECM back to the re-manufacturer & sent them a list of the things that it was doing before I sent it back & what its doing now that I got it back.

 

They checked it & thought the memory was bad.

they flashed it again & thought something was bad again.

they replaced the memory chip and all of the circuitry associated with the WTS light

They reflashed it again & sent it back to me.

 

I just installed it & the WTS light is acting normal again.....  Yea :)

 

while the truck was running it sounded like the AC was kicking on & off (I could hear the idle changing.

I double checked & it was off & the compressor was not cycling.

I put a meter on it to see what was going on & noticed that the AC noise was going from 10 mV to 1xx mV/200 mV & the DC Voltage was dipping as well.

I reached down & put my hand on one of the Grid heater relays & it was cycling off & on. 

 

Yes its a little chilly here this morning (68*) and the truck has not run in a week, so the motor is stone cold.  but.......... its San Diego........ it does not really get cold here..... 

 

Here is a quick video of the meter while this is happening.

 

 

So, my questions:

Is this a problem?

Do the grid heaters go bad?

Do the grid heater relays go bad?

 

BTW, before I started the truck I tried to connect to the truck with my OTC Genisys & it would not talk @ all.  I guess that will be the next thing to screw with.......  something is up.  :(

 

Edited by Bobalos

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grid heaters are controlled by a trigger in the ecm.  

 

Does the wts light stay on longer when you key on, or does it just turn on and off?  

 

Given the history my speculation is that the ecm is still having issues.  

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I was not sure if I communicated the issue correctly so I went to make another video to show you what it was doing.  to make a long story short, I started the truck probably 20 times & took it for a couple of short rides around the block & everything appeared to be working correctly (with the exception of the comm issue & the grid heaters cycling on & off & dragging the alternator down with it). 

 

I went for a walk with my neighbor for about an hour & just got back & read your post.

So....... I figured I would do another video of what its doing in the truck & its now doing EXACTLY the same thing it was doing before I sent it back to the ECM company for the second time.  It was NOT doing this before I sent it to them, It was simply having issues with the lift pump (as well as the intermittent comm issue)

 

To make it clear right after I installed the ECM & started it a bunch of times.  the WTS light was working exactly how I thought it should: 

~ Turn on the key & it would turn on the lift pump (you can hear the gauge in the video below going bsssst, when the pump kicks on),

~ It would turn on the WTS light, then it would go out & the truck was ready. 

~ Hit the ignition & it would fire right up & everything was fine, except it sounded like the AC compressor was cycling & dragging the idle down a bit.  the Meter test followed that & it showed it was the Grid heaters causing the idle to drop/etc.

 

Sorry about the language, Im SOOOOOOOOOO over this ECM BS.......

 

 

Does anyone have any suggestions for a competent ECM place???? 

 

Bob

 

 

 

Edited by Bobalos

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I know its only been a few hours, but anyone have any suggestions??? 

 

I have got to get this thing running properly again.  Im 1/2 tempted to get a new alternator for it & Maybe new relays and grid heater. 

 

I dont know which came first the chicken or the egg. 

 

and........ is the ECM broken again???  :(

 

thanks folks

Bob

 

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grid heater relays won't help.  If the grids are getting kicked on and off then the ecm is doing it.  If the wts is not staying on the there is some sort of issue in the grid control part of the ecm.  

 

 

your WTS light is still delayed by a good 10 seconds in the video.  ECM issue.   it should come on as soon as you key on.

 

 

this sucks that you are dealing with this

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everything worked correctly for a bunch of times, & then it crapped out again & its doing the same thing it was doing when I sent it back the last time.

 

it seems to me that what is really broken is the EEPROM.  what can cause that?  the folks @ the rebuild company are useless.  all they know is "I put it in the simulator & its broken" & "I put it into the simulator & its working". 

 

the only reason I mentioned the Grid heater is because it is creating a LOT of AC noise & dragging down the Alt a bunch more than I think it should be.  (EA Grid heater ohms out @ 0.3 Ohms to ground.  I dont know if that is good or bad, but it sure seems like that would draw 40 Amps EA, which seems like a bunch......).  the voltage dragging down when the heater comes on could have nothing to do with the grid heater itself, but that the alternator is crapping out (or crapped out).  I have not put one on the truck, EVER.  18 years & 200K.......

 

Could the Alternator be causing the ECM to crap out?

 

How about wiring?  pinning out the entire harness is probably not gonna be a practical idea, but I could pin out some circuits if I had some idea of where to start. 

I dont want to buy another ECM & have it blow up too, but it sure does look like its bad........ something must be causing it. 

 

I cant tell if the communication issue is a red herring or is trying to tell me something.  I tried to talk with it with both of my scan tools even before I started the truck & it would not talk.............. 

 

thanks again folks.

Bob

 

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1 hour ago, Bobalos said:

Could the Alternator be causing the ECM to crap out?

I'm not that bright on rest of questions but yes alternator with high ac noise can fry electronics. We can't stress this enough when it comes to hunting electrical problems. 

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however I think the likely issue is just a shotty rebuild of the ecm.  AC noise shouldn't fry the ecm that fast.  

 

I would replace the alternator if you are seeing a ton of ac noise for good measure, but I dont think it is what is causing the issue, I think that the issue is the source of the rebuilt ecm.  

 

rebuilt ecms are a crap shoot.

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Any suggestions.on where to go?  I'm not impressed with this company.

 

The AC noise is fine as long as the grid heaters are.not on....  I will unplug them to test. 

 

 

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The blips I saw in your video seem very short compared to how mine react. Mine are on for a few seconds them off and the process starts over. Not sure what that means it just looks different the mine behaves.

 

I have to agree with me on both of the above. AC voltage will kill the electronics over time. I would suspect the ECM also. Been there done that and have a very nice ECM paper to remind me of it. I would check with Cummins and see what they can do for you with an ECM. That is where I would go first. They might be to pricey up front but I wish I had gone there first. There is no telling how much I spent getting my cheap one.

 

You might check this out. Someone else going thru the same thing.

The Go ECM he mentions Is worth checking out. I have no experience with them but an old member here mentioned a good while back. @cajflynn. Stumbled across the post while googling one day and he mentioned them with another co that he had success with. He got 1.3 million miles out of his 2nd gen before a wreck took out. Hauled boats boats with it for a living. All and all though I have to agree on the crap shoot part of ECM rebuilders.

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8 hours ago, Bobalos said:

The AC noise is fine as long as the grid heaters are.not on....  I will unplug them to test. 

 

 

Then to double check remove the alternator and have it bench tested. That will double verify. 

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