Gauges, Bus and Distribution Block issues

[dhubbard]

Hello,

 

I have a 2002 Dodge Ram 2500 24v 5.9 with intermittent electrical issues. Sounds like fun - right? New PCM, rebuilt instrument cluster, paid so-called electronics experts to troubleshoot/repair, still have bus communication errors and half of the gauges (tach, oil pressure, H20 temp) do not currently work. Experts or I can fiddle/clean with various stuff and everything will work for a bit, but that nirvana is short lived - a few hundred miles at most. 

 

My latest exploration has found that the "power distribution block" (what are these blocks called?) in the under hood fuse box will not tighten as securely as I think it should... just as the 6mm bolt starts to pull up tight, it screws the available threads all the way through the "nut" that is captured in the lower block... so, the upper block can not be held tight to the lower. The upper block does seat fairly well to the lower, but the blocks move a bit relative to each other. I see three possibilities: 

1) it's not a problem, i.e. it is working as designed, the designer of this block carefully constructed the these blocks so that it is not possible to over tighten it and I need to find some other "bad" connection to fiddle with

2) the captive "nut" in the lower block has pulled up due to over tightening

3) the engineer that design this block had no clue...

 

Assuming that option 2 or 3 is correct, I thought I'd simply replace the screw that is captive in the upper block, but there is a very secure retaining washer buried an inch down in a tight space. My attempts to remove it have failed. 

 

- So, any thoughts as to which option listed above, if any, is correct?

- Any suggestions for removing the retaining washer? 

- Do I just need to R&R these blocks with new?

- Do you know if these blocks are available? Do you know the correct name for these blocks?

 

Answers to these questions or suggestions to just move along and look for a bad connection or short... are appreciated. 

 

Thanks in advance,

DH

 

PS. the grounds appear to be good, they measure very little resistance. 

 

 

Edited October 3, 2017 by dhubbard

[kzimmer]

My harness plug in the fuse box with the bold does the same thing. Apparently by design? But mine is very difficult to get snug and takes some finness. Sneeze and it will break loose. When I bought the truck it had "no bus". Found that connector loose. Then I installed HID's. Back no "no bus". Removing the HID's fixed the issue until I got filter caps on the ballasts.

 

When I tighten mine I push down on the connector, wiggle it a little to make sure everything is moving right, while I tighten it with a socket in my hand, so I can use my fingers to feel that point where it's right enough before it breaks loose again.

Edited October 3, 2017 by kzimmer

[dhubbard]

^^ Thanks kzimmer. Yes, I can tighten this bolt such that it is almost tight, but it doesn't hold quite that tight after some time/miles. I do wonder if this is as designed... Thanks again.

[dripley]

 I have read many threads of people thinking they have over tightened and stripped theirs, but it would appear to me it is by design. Mine is the same way. I have some electrical gremlins my self, different from yours though, but have experienced the temporary nirvana you have gone thru. 

[dhubbard]

41 minutes ago, dripley said:

 I have read many threads of people thinking they have over tightened and stripped theirs, but it would appear to me it is by design. Mine is the same way. I have some electrical gremlins my self, different from yours though, but have experienced the temporary nirvana you have gone thru. 

dripley, Thanks for your post - may you experience more electrical nirvana. 

 

So far we're 3 of 3 that the 6mm bolt will not snug up tight. Yet all 3 of us experience or have experienced electrical issues... I do know that I recently took the truck back to one of the "professionals" right after some of the recent nirvana ended and he claimed that tightening this bolt fixed the issue, well, temporarily... If this is true, then there appears there may be a relationship between nirvana and tightness! 

 

Looking forward to hearing of others experiences! Well designed? Or designed without a clue?

 

 

[dripley]

The nirvana I experienced never involved that plug. Mine was engine surging. Seemed to go away almost every time I disconnected the batteries. It finally went away after messing with the map sensor. Surging is still gone but new issues with the map. Think mine is wiring related and never considered that plug. Probably ought to just to eliminate it.  

[jlbayes]

It was 100% designed that way.

 

What are the codes you have present? The ECM sends ect, oil and tach to the pcm. What is being "messed with" to get the functions back for a short period of time?

[dhubbard]

1 hour ago, jlbayes said:

It was 100% designed that way.

 

What are the codes you have present? The ECM sends ect, oil and tach to the pcm. What is being "messed with" to get the functions back for a short period of time?

 

jlbayes, Thanks for the reply.

 

Truck has codes: P1698 and P0216, but the P0216 is only shown after the P1698 is triggered. P1698 is not present during periods of nirvana.

 

My history with electronics on this truck: 

I replaced battery cable to starter (it had a broken battery clamp) and I had nirvana for a couple of months; I thought I was a hero - ha. Then I discovered that I can remove the instrument cluster (clean or not clean connectors) and the codes will be reset and things work for a bit. Local shop that does the alignment for my Miata, said that they'd look at it and they replaced one of the connectors between dash and cluster and it worked for a week or two.  I had the original cluster rebuilt (United Radio) and things were good for a day or two. Local diesel experts said the original PCM was noisy on their scope. They swapped in another from a truck they had and it worked (for a test in shop). Had PCM rebuilt. Rebuilt PCM worked for a day, maybe two. Experts said it must have been a bad rebuild, found a new PCM and it worked for a week. Experts said everything looks good on their scope as the signals go to cluster (I expect from a location under hood) and they recommended another cluster. I found a used cluster and swapped it in, yep, it worked for a couple of days...  Experts tightened the 6mm bolt and it worked for 3-4 days. I decided to explore this connection, had questions and filed original post.

 

I suspected that the block was designed such that it could not be overtightened. Is the goal to tighten the screw as much as it will allow? Or is the goal to simply screw it all the way in such that it is loose-ish, but fully seated?  If the goal is to have this bolt as tight as possible, mine loosens with a few miles or few hundred miles, I can try to fix that with blue locktite. If it is supposed to be tight, I'll also claim it's a lousy design.

 

I haven't replaced ECM or wiring harness... 

Edited October 3, 2017 by dhubbard

[jlbayes]

https://mopar1973man.com/cummins/articles.html/24-valve-2nd-generation_50/51_engine/obdii-error-codes_94/p1698-no-bus-message-received-from-pcm-r141/

[dhubbard]

^^^ jbayles, Thanks.

 

I'll find a (different) expert with the not inexpensive scan tool and see what we find...

 

[Mopar1973Man]

Best thing I can say it to pull lose all the CCD devices except ECM and PCM and see if that helps a little if there is any shorts to ground or bad modules like overhead computer fouling the CCD network. Remember the PCM is the source of all CCD signals. Also remember when a device talks over the CCD every device listens for needed data. For example ABS transmits speed data the ECM, PCM and cluster will listen. Not so much as passing from ABS to PCM then cluster.

 

[dhubbard]

^^^ Mopar1973Man, Thank you. 

 

I'll need to find another expert to troubleshoot the CCD network. Maybe I'll have better luck this go around. 

 

FWIW, I reassembled the fuse box, snug'd the 6mm bolt and the gauges were non-functional. I'm not sure that I believe the previous expert when he told me that tightening this bolt made a difference - maybe, probably not. However, I then swapped the cluster back to the rebuilt original and they do (for now) work. I'm guessing that removing the cluster performs a reset of the CCD - I wonder if this guess is correct? 

 

Again, THANKS to all that have taken a moment to reply.

[jlbayes]

Ok, that sounds like you have terminal issues with the cluster connectors. It does not take much to spread them or push out. I would start there. The pcm and cluster in the 98-02 are the masters on the ccd bus.

[dhubbard]

12 hours ago, jlbayes said:

Ok, that sounds like you have terminal issues with the cluster connectors. It does not take much to spread them or push out. I would start there. The pcm and cluster in the 98-02 are the masters on the ccd bus.

 

jlbayes, Thanks for the suggestion. 

 

I should check these again. I've never been convinced the the connector on the left seats as well as the one on the right... but my efforts to date did not, obvioulsy, yield success.

 

I made an appointment with a local dealer for a couple of weeks from now; it should be acting up again by then.  

[Mopar1973Man]

Probe pins 3 and 11 on the OBDII port do this in reference to ground. Normal CCD voltage should be 2.49 and 2.51 volts. If the voltage is not these numbers then that leg of the CCD bus is the problem. 

 

 

 

 

[dhubbard]

12 hours ago, Mopar1973Man said:

Probe pins 3 and 11 on the OBDII port do this in reference to ground. Normal CCD voltage should be 2.49 and 2.51 volts. If the voltage is not these numbers then that leg of the CCD bus is the problem. 

 

Mopar1973Man, Thanks. I'll measure voltage on pin 3 to ground and pin 11 to ground and post those results. However, I assume I will get different measurements once the gauges start acting up again, which appears to be synonymous with communication errors. 

[dhubbard]

On 10/5/2017 at 10:46 AM, dhubbard said:

 

Mopar1973Man, Thanks. I'll measure voltage on pin 3 to ground and pin 11 to ground and post those results. However, I assume I will get different measurements once the gauges start acting up again, which appears to be synonymous with communication errors. 

 

The gauges started acting up today, before I took a reading. Assuming I'm probing the these pins under the correct conditions (key on, engine not running), I don't measure either of those voltages. On my modest, err... cheap DMM, Pin 3 measures 2.45 or 2.46v (the reading flips between these voltages). Pin 11 flips between values that range between 2.39 and 2.45v. 

 

So, neither is correct. Both are low. Pin 11 is way low if it is supposed to read 2.51v. Does this exercise tell me anything other than it's not right?

 

Thanks.

Edited October 7, 2017 by dhubbard

[Mopar1973Man]

Remember if data is being transmitted it will jump up and down. Those voltage are while the system is at rest. Might cycle the key off and pause 10 seconds and back on. Then pause awhile and see if the voltages are closer.

 

It tells that it's not shorted to...

Ground

+5V

12V

Edited October 7, 2017 by Mopar1973Man

[jlbayes]

It appears they are shorted together or the bus goes idle at the point of the gauges messing up.

Edited October 9, 2017 by jlbayes