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Communication issues (& more)

Bobalos
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Me78569

Me78569

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Posted

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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dripley

dripley

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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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Bobalos

Bobalos

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There is a Alt/Start company down the road from me that I used to use all the time when I was in college & the old guy that worked there was very good & would help just about anyone out. 

 

I will swing by with the Alt & see if they can bench test it.  its been 20 years, who knows if they are even owned by the same guy. 

 

Im still unsure where to go for the ECM.  I guess I can try Cummins on Monday, there is a local Cummins place here.  I wonder where they get them rebuilt.......

 

thanks

Bob

 

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Bobalos

Bobalos

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Mopar1973Man (I think your name is Mike, but dont remember exactly.......).

 

I seem to recall in one of your other posts you mentioned that you dont have your grid heaters plugged in most of the time.  How do you get around not getting codes?  or do you get them & just ignore them??? 

 

I was just playing with mine & found that when I unplugged the relays I got a P0380, Po382 & P1291, which I think are all grid heater related.

 

My OTC will not connect to the truck, but my $5 China Freight one will both get the codes & clear them.  go figure.............. 

 

I started the truck up w/o the grid heater relays plugged in & the AC noise went to 12-16 mVAC (slowing moving around) & the DC was 14.11 & rock solid. 

 

I found that the Hot side on the forward relay was a VERY bad connection.  it looks like it was hit or something & the connection was opened up enough to make it sloppy on the post on the relay. 

 

I cleaned all 4 connections up & tightened up that one connector & wouldn't you know it, it seems pretty happy now.  I read both the AC noise & DC voltage & it seems MUCH better.  in fact its more stable than when I had the Grid relays disconnected.  Im getting 12 to 13 mVAC & 14.1 VDC VERY solid........... 

 

the WTS light is still inconsistent, but I was doing a bunch of starts & stops & setting DTC's & clearing them & whatnot, so Im going to give it an hour & try it again & see if its happy or if its just screwing with me again...........  LOL. 

 

Im hesitant to call this thing fixed, but.......... it sure does seem a lot more happy.......

 

Bob

 

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JAG1

JAG1

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Posted (edited)
6 hours ago, Mopar1973Man said:

Be warned all ECM today are remanufactured there is no longer any new ECMs...

Isn't there anyone that might be building an aftermarket ECM?

 

Is there a problem stemming from the fact that information required to build one, is strictly proprietary information?

Edited by JAG1
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Bobalos

Bobalos

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In my case that would not be of any help.  Im in California, & it has to retain all of the OEM stuff (with some exceptions).  Believe it or not I have to get my truck "smogged" every other year (started 4 or 5 years ago).  They dont do a sniffer test, just visual inspection & connect to the ALDL to make sure that its talking & there are no DTC's stored. 

 

I saw briefly last night that someone has the 2002 (ish?) ECM's working on the 98/99 trucks.  I have not looked into it @ all, but will sometime this week.  not sure if there is any benefit for me........... 

 

Bob

 

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Bobalos

Bobalos

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good news is that it appears that the Comm Bus wires look to be in good shape & there are no shorts to ground or opens or anything.  I pinned it out between the ECM, PCM & ALDL  & it all looks good. 

 

The bad news is that its still giving me that DTC. 

 

I will make some calls tomorrow & see if I cant find someone that can get me a good ECM. 

 

If anyone has any other things they think I should look into, Im open to it.........

 

thanks

Bob

 

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  • 2 weeks later...
Bobalos

Bobalos

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Update (hopefully the last for a while.........) :

 

a local shop (Steven Bruce, at Diesel System Services. blacksmokin.com), looked @ the truck & could not find anything wrong with it (other than what I found).  He put his "test ECM" into the truck & it fired up & ran correctly.  WTS light worked properly, Lift pump operated properly & Communications worked properly. 

 

He has a source for ECM's that he said is the company that remanufactures the ECM's for the big 3 & for a lot of the heavy equipment folks.  He ordered me an ECM & had it shipped 2nd day air to Kalipornia (they are in the Easter Time Zone).  Steve was kind enough to allow me to drive the truck for 4 days with his test ECM in it until the new one came in........  

 

installed the new ECM, everything worked fine for 3 days ........... until................  Im completely loaded up & ready to to head out to the desert.  it would crank but not start.  He came out to my house (Thursday night, WAY after hours) & did a bunch of tests & we were able to get it running, however were not sure why.  the last thing we were messing with was the Cam Pos Sensor.  However......... what was strange to me was that with the Cam Pos Sensor unplugged the truck would start & run just fine & would not turn on the CEL until the truck had been running for 13 or 15 seconds.  

I was not comfortable taking everything & everyone out to the desert if we did not "fix" anything, so I told him I would drop it off @ his shop on Friday morning (assuming it would start & run).  I went down to Cummins Friday morning & bought both the Crank & Cam position sensors.  On the way to his shop with the truck it started Bucking & trying to die (the CEL came on), when I took my foot off of the gas pedal.  

 

when I got to his shop he scanned it & it came back with the Crank Pos Sensor DTC.  THAT seems consistent with "some" of the issues I had been having with the truck.  while he was under the hood he swapped both of them & then did a bunch of diagnostics to make sure that everything was happy.  I picked up the truck on Sunday after we got back from Church & paid him for his time on Thursday evening & Friday.  

 

So, some things that came out of this......... 

Steve showed me how to start the truck w/o the key being on & 2 relays removed from the PDC to test to ensure that the Injection pump works properly.  

I dont understand what the Cam position sensor does if the truck will start & run fine w/o it even being plugged in.......................

 

Now I get to fight with the first ECM company & see if they will refund my money for the service they did not provide me (twice), however I have to see if they screwed up my original ECM so badly that the second company will or will not take it as a core........

 

having multiple issues REALLY is a PITA.....  

 

thanks again folks for all of the help during this.  time to replace the heater core and dash & hopefully the old girl is ready for another 100K to 150K before she needs more work.  Im sure the trans will need frictions before then, but that is OK with me.  

 

Bob


 

Edited by Bobalos
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Mopar1973Man

Mopar1973Man

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23 minutes ago, jlbayes said:

The cam sensor on the 98.5-00 trucks effectively is only used for correlation. It has no direct action on the truck. The crank sensor gets all the info it needs and sends it to the ecm & pcm.

 

Basically only sees TDC #1 that's all being it only a single tooth tone wheel..

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