ACC/CMS fault

[buddy110]

Hey everyone,
While driving from Yuma to Las Cruces 10 days ago my CMS and ACC quit working simultaneously. I spent the last hour with my foot on the pedal. And after an hour my leg muscles hurt

Anyway, We arrived at the RV park, I pulled in my spot, shut her off and proceeded to read the codes with my scanner. None stored. As it turned out we didn't like our spot and moved to a much nicer one. I noted that the fault had disappeared. Today while heading to Austin the same thing occurred. When I stopped this time I left the motor running and read the code #5606. Looks like a trip to a shop while we are here. It takes special software in order to find unstirred codes.

Ugh

[jrugarber]

Bruce,
Similar to you, we have experienced loss of the CMS/ACC, the culprit seems to be when it rains as we have not experienced it any other time. I’ve learned to live with it, and when I see rain head our way I start stretching my right calf in preparation.... usually by the next day it has worked itself out and it returns to normal. If you find any pertinent information as to a cause feel free to pass it on.

[brobox]

My 19 had the problem after the dash ATC code was cleared after an alignment. Rebooting the chassis with the two switch next to the chassis batteries solved the problem. I left the switch off for about 5 minutes.
If you drove in rain, I would suspect that first.

[Nowabeachbum]

Yup, rain was the only time I saw a fault also. Then after it dried, it cleared.

[buddy110]

Both times this occurred it was dry as a bone

[Gary.Jones]

Bruce

My ACC and CMS fault frequently. I have written about this problem a lot and have been in the shop 3 or 4 times (NIRVC, Spartan, and Cummins shops) and the problem has been worked on repeatedly. It still occurs but now occurs less often but still occurs for predictable as well as random reasons.

First, it occurs frequently when driving in heavy rain. Everyone's guess is that it is the result of water intrusion into the J1939. At least on my coach, the J1939 communication bus ends right beside the RADAR transmitter on the front cap. If you look, you will see what is called a terminating resistor. That resistor puts a common resistance load between the two leads of the J1939 communication bus. What we think happens in the water intrusion scenario is that water shorts the two leads together and loads down the J1939 communication bus. I have had a shop mechanic try to insulate that terminating resistor connector and did a worthless job on it. I have removed his mess, and thoroughly taped the front terminating resistor connector and added a small steel arm that is held to one of the bolts holding the RADAR on, and is vertical, and used to hold the waterproofed terminating resistor connector vertical in an attempt to let even my waterproofing job let the water shed off of that connector. My failures are much less common now. There is also a terminating resistor in the back of the coach too but I have not found that sucker and repair techs at NIRVC don't seem to know where that sucker is either. I am going to ask Spartan and my guess is that one also needs to be waterproofed completely.

Although water intrusion appears to be a big reason, my ACC/CMS also fails for no weather reason at all...... after lets say two days of dry traveling, no water in sight or near. It just faults. I notice that the coach is no longer holding its speed and the dash shows that the ACC/CMS has faulted. Sometimes ACC fails without the CMS and other times they both fault at the same time. However, regardless I must feed the diesel myself. Usually in 10-15 minutes the CMS will come back on line spontaneously. Sometimes not. I wait until I find a safe exit or truck stop or rest area, pull in and shut down the Cummins and the salesman switch for 3-5 minutes, and fire everything back up and that resets everything.... no need on my coach for anything else.... just the patience to stop and wait it out and allow it to reset. However, going through DC or Los Angeles is not the right time...

I just had Spartan work on this again back in November. My tech said WABCO had just released an update to software and it would take care of the problem. It was installed and we had to take a long drive to let the WABCO learn things like what a tree looked like, or mile markers (seriously) and to ignore them. I was hopeful, but my ACC/CMS faulted on the way home from Charlotte (so, no JOY)

I could care less about the ACC because I HATE THE ACC..... what a pain in the a$$ that innovation is!!!!!! I can live with the CMS, but the ACC could die and go away forever and I would thank God for intervening in a positive way. On my '19, I can turn the ACC off and stop dealing with it. The system still faults for no reason in dry weather, however.

Try my experience. My coach has been doing this since I picked it up from Atlanta. Don't think it is ever going to be immune to this problem. I am aware that there are some who know exactly how to make both ACC and CMS go away forever if you really want it done and sign the right papers. It now happens one or twice in a 2-3,000 mile trip.

Gary

[buddy110]

Originally Posted by Gary.Jones

Bruce

My ACC and CMS fault frequently. I have written about this problem a lot and have been in the shop 3 or 4 times (NIRVC, Spartan, and Cummins shops) and the problem has been worked on repeatedly. It still occurs but now occurs less often but still occurs for predictable as well as random reasons.

First, it occurs frequently when driving in heavy rain. Everyone's guess is that it is the result of water intrusion into the J1939. At least on my coach, the J1939 communication bus ends right beside the RADAR transmitter on the front cap. If you look, you will see what is called a terminating resistor. That resistor puts a common resistance load between the two leads of the J1939 communication bus. What we think happens in the water intrusion scenario is that water shorts the two leads together and loads down the J1939 communication bus. I have had a shop mechanic try to insulate that terminating resistor connector and did a worthless job on it. I have removed his mess, and thoroughly taped the front terminating resistor connector and added a small steel arm that is held to one of the bolts holding the RADAR on, and is vertical, and used to hold the waterproofed terminating resistor connector vertical in an attempt to let even my waterproofing job let the water shed off of that connector. My failures are much less common now. There is also a terminating resistor in the back of the coach too but I have not found that sucker and repair techs at NIRVC don't seem to know where that sucker is either. I am going to ask Spartan and my guess is that one also needs to be waterproofed completely.

Although water intrusion appears to be a big reason, my ACC/CMS also fails for no weather reason at all...... after lets say two days of dry traveling, no water in sight or near. It just faults. I notice that the coach is no longer holding its speed and the dash shows that the ACC/CMS has faulted. Sometimes ACC fails without the CMS and other times they both fault at the same time. However, regardless I must feed the diesel myself. Usually in 10-15 minutes the CMS will come back on line spontaneously. Sometimes not. I wait until I find a safe exit or truck stop or rest area, pull in and shut down the Cummins and the salesman switch for 3-5 minutes, and fire everything back up and that resets everything.... no need on my coach for anything else.... just the patience to stop and wait it out and allow it to reset. However, going through DC or Los Angeles is not the right time...

I just had Spartan work on this again back in November. My tech said WABCO had just released an update to software and it would take care of the problem. It was installed and we had to take a long drive to let the WABCO learn things like what a tree looked like, or mile markers (seriously) and to ignore them. I was hopeful, but my ACC/CMS faulted on the way home from Charlotte (so, no JOY)

I could care less about the ACC because I HATE THE ACC..... what a pain in the a$$ that innovation is!!!!!! I can live with the CMS, but the ACC could die and go away forever and I would thank God for intervening in a positive way. On my '19, I can turn the ACC off and stop dealing with it. The system still faults for no reason in dry weather, however.

Try my experience. My coach has been doing this since I picked it up from Atlanta. Don't think it is ever going to be immune to this problem. I am aware that there are some who know exactly how to make both ACC and CMS go away forever if you really want it done and sign the right papers. It now happens one or twice in a 2-3,000 mile trip.

Gary

Mine failed again today in bone dry Texas weather. I need cruise in some form. Next leg I will try running with acc off and see if it still faults. I'm not a huge fan of either. I had high hopes for ACC, but it slows me down way too soon and takes forever to recover. Will cruise work without ACC on?

[Rollin101]

Originally Posted by buddy110

Mine failed again today in bone dry Texas weather. I need cruise in some form. Next leg I will try running with acc off and see if it still faults. I'm not a huge fan of either. I had high hopes for ACC, but it slows me down way too soon and takes forever to recover. Will cruise work without ACC on?

Yes it will. My ACC is off for the same reasons you stated, but my cruise works fine.

[LWBAZ]

Bruce, I suspect you've already thought of this, but in case not...

In the center of the front cap, down near the bottom, is a plastic panel, behind which is the radar for the ACC/CMS functionality. If you get enough bugs and/or road grime on that panel, the system doesn't like it and will stop working.

If memory serves me, you not only have to clean the panel, you have to leave the engine off for some number of minutes for the system to reboot. The point being that if you pull into a rest stop, leave the engine running, and clean the panel, the system will still be non-functional when you pull back onto the roadway. Don't ask how I know that.

[Gary.Jones]

Bruce

On my coach, with the joystick, I can pick either ACC Long, Middle, or short (which is still way too long for me) and then Off. Its some other work like defeated on the screen or similar word. That is what I can see when I fire up the Cummins each time. I immediately switch the the defeated position, and press down and that sets it in that mode. That means ACC is now not operational. Conventional old style cruise control and CMS are still operational.

So, I try to always move my dash control to turn off the ACC. I get a warning on the dash that I have turned the ACC off but the CMS box is still green. That is the way I always drive. I typically cruise at 68 mph on this Cornerstone (it wants to run faster than the 450) and that is the way we travel unless the system fails. When it fails, I note that the coach is slowing down for no reason, and when I look at the dash, the display says ACC Fault or CMS fault.

What Larry says is true.... in heavy snow or slushy road conditions, the ACC/CMS can fail due to crud buildup on the RADAR screen, but that is not the problem 100% of the time for me on my coach.

And yes the answer to your question is that my coach definitely still has old fashioned cruise control available, unless the whole system has failed.

Gary

[buddy110]

Thanks everyone. I never tried to drive with ACC defeated so I wasn't sure how locked not ACC the systems were.

I did look at the radar screen. it's clean. Odd though that the system worked fine all the way to California and then acted up on my way east. I'll live with it for now, but plan to have that and a few other items fixed at the mothership when I return this spring. Maybe I'll get lucky and they will actually find a solution....

[Rollin101]

Originally Posted by buddy110

Thanks everyone. I never tried to drive with ACC defeated so I wasn't sure how locked not ACC the systems were.

I did look at the radar screen. it's clean. Odd though that the system worked fine all the way to California and then acted up on my way east. I'll live with it for now, but plan to have that and a few other items fixed at the mothership when I return this spring. Maybe I'll get lucky and they will actually find a solution....

Another reason to stay out of CA.😀😀

[buddy110]

Originally Posted by Rollin101

Another reason to stay out of CA.😀😀

Agreed. DW booked a spot in Yuma AZ. Turns out it wasn't in Yuma, rather it was in Winterhaven California, right near the dunes. Dry, dusty, windy etc, etc. Yuma was 15 miles away. Maybe the dust contributes to the ACC issues. Who knows.

[Rollin101]

Originally Posted by buddy110

Agreed. DW booked a spot in Yuma AZ. Turns out it wasn't in Yuma, rather it was in Winterhaven California, right near the dunes. Dry, dusty, windy etc, etc. Yuma was 15 miles away. Maybe the dust contributes to the ACC issues. Who knows.

We stayed at the Army proving grounds, during the Winter, for a few years. It’s about 15 miles North of Yuma.