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Tall Cowboy · 12-04-2021, 10:46 PM

I have recently purchased a Monaco Diplomat 2000. The abs light has come on and won't go out. I would like to DIY the project. I have tried to do a diagonistic test. It has a J 1939 ECM but the ECM is not communicating with the scan tool. Therefore, I have 2 problems. 1. ABS light. 2. ECM communication problem. Any advice would be appreciated.

8.3Oilbuner · 12-04-2021, 11:25 PM

Good evening Tall Cowboy; Most Monaco Diesel Pushers of that year, I had an 2000 Windsor & now have an 01 Windsor, have an ABS module in the outside electrical bay under the drivers seat. I could sit here a write a long article about the problem you are having as others have had the problem you are describing and so have I. In the search box at the top right of this page try typing in, ABS light on in a 2000 Monaco Diplomat, and you are sure to have a wealth of reading with pictures. You will find info on how to run Dianostics on that module.

Give the search box a try and come back if you have more questions. There should be numerous posts on this subject for your coach!

Dougmore · 12-05-2021, 04:21 AM

I had the same issue. Once you find the ABS module look at it closely. You should see a small push button 1/4 inch in size. That is a reset switch. Mine had gotten moisture in it and became stuck in the "ON" position. I removed the board, cleaned the switch with WD40 and a few blasts of air. Worked for me....

jacwjames · 12-05-2021, 05:33 AM

The ABS system does not communicate with the ECM. You will also need a specfic scan tool do communicate with engine ECM, Scangauge is one, there are others.

Do you have a manual for the coach, if there is an ABS system it should cover on how to recover fault codes.

As Twinboat said, there may be a ABS module in your drivers side front electrical bay, it will look like this if you have one. http://www.nwrvsupply.com/product/16614041.html

If you have one of these post back and I'll try and help as to retrieving fault codes if you can't figure it out.

Biljol · 12-05-2021, 06:26 AM

Also due to the year of your coach you most likely have a J1708 diagnosis port. So be sure you can read J1708.

The Porte look the same but the data protocol is different.

Biljol · 12-05-2021, 07:42 AM

I now also remember my coach has 3 diagnosis ports

ECM
ABS
transmission

Tall Cowboy · 12-05-2021, 02:41 PM

Quote:

Originally Posted by jacwjames

The ABS system does not communicate with the ECM. You will also need a specfic scan tool do communicate with engine ECM, Scangauge is one, there are others.

Do you have a manual for the coach, if there is an ABS system it should cover on how to recover fault codes.

As Twinboat said, there may be a ABS module in your drivers side front electrical bay, it will look like this if you have one. http://www.nwrvsupply.com/product/16614041.html

If you have one of these post back and I'll try and help as to retrieving fault codes if you can't figure it out.

Thanks Jim,

I checked your link and I do have a module lie the one shown. I get a red indicator light when the ign switch is on. I checked both of the fuses and they were good. I pressed the test button, but nothing seemed to happen. don't know what to do next. Maybe buy a new motorhome. HaHaHa at least I now know the module location.

Tall Cowboy · 12-05-2021, 03:49 PM

Quote:

Originally Posted by Biljol

Also due to the year of your coach you most likely have a J1708 diagnosis port. So be sure you can read J1708.

The Porte look the same but the data protocol is different.

The operation and maintenance manual that came with the coach is for Cummins ISC engine. On page 1-20, there is diagram that shows the ECM link to a J1939 datalink which links to the transmission, ABS and ASR. The scanner that I have is supposed to read the J1939 and also a J1708. I cannot get a reading from the ECM link. I had Love's truck stop mechanic and the Cummins service mechanic to diagnose the abs system and they also could not get a reading on their scanners. I'll keep looking for a fix but it seems to be elusive.

Tall Cowboy · 12-05-2021, 04:08 PM

Quote:

Originally Posted by Biljol

I now also remember my coach has 3 diagnosis ports

ECM
ABS
transmission

What do these ports look like?

Biljol · 12-05-2021, 06:20 PM

Near my steering column on the left (street) side there are 3 ports I believe the transmission and ecm are both 6 pin connections the ABS looks like a odb port.

I could be wrong and have the ABS and transmission reversed but above each one is labeled what they’re for.

There should also be an ecm port in the rear engine compartment.

jacwjames · 12-05-2021, 06:37 PM

OK, you have the module. This is the ABS diagnostic module to read the fault codes.

My instructions to read the code is to

Turn the key on without starting the engine
Fully press the brake pedal one time
Go around to the module and press the black button for less then 2 seconds.
At that point the module goes through a diagnostic routine and if you have fault codes will light the small LED light for a blink code. If you have no fault codes it will blink 1-1. It you have fault codes it will blink them in a two number sequence i.e. 1-5 etc.

Follow the above instructions and see what you get. Do not press the button for more then 2 seconds. I did that once and it put my system in Dyno Mode and took a lot of research to get it to clear this out.

In the past I've had different codes. On my front drivers side wheel it showed that the sensor was not within the gap range. Pulled the sensor, cleaned it, put it back in, drove the coach and the ABS light went out.

The last time my ABS light stayed on I tried to retrieve the codes and it didn't work. The button was not working correctly, this happened to me before and I took the whole module out and used compressed air on the button quickly pressing it. Over time dirt and debris get in the button and blowing it out usually would solve the problem. This time it didn't. So I took the module back out and then "gently" pried the button out of the small housing. Under the button is a small spring plat that actually makes contact to start the diagnostics, but the plate wasn't lifting off the contact, so I "gently" bent each leg a little to elevate the spring plate. Put it all back together and that solved my problem. I put 10K on the motorhome since then and still good.

Do the above and post your findings. Good luck

Also, FWIW, I use a Silverleaf VMSpc to monitor the vitals of the engine and transmission while driving. You can set up the screen however you want. In my case I monitor engine and transmision temp. Engine rpm, oil pressure, turbo psi, Speed, gear, fuel consumption, miles, hours, trip log. Pretty robust system. Plus it provides fault codes. I was having trouble with this system earlier this year but got a new tablet to display the info on and on my last 5K trip it worked great.

There is another system out there called Bluefire, does about the same thing.

This is my 9,999 post, hope it helps.

Tall Cowboy · 12-05-2021, 10:07 PM

Jim,
I did as you suggested. First, turned on the ignition switch. second pressed the brake pedal once. Third pressed the test button on the module. Nothing happened except the red light on the module was on steady. Shut everything off and went through the process again with the same result. I will go to the second part of your message and try cleaning the test button contact in the morning and see if that works.
Thanks much for trying to help me figure this out.
If I get it to flash the codes, how will I know what the code flash sequence means

jacwjames · 12-06-2021, 05:40 AM

Sounds more and more like it is the button. Just be careful taking it apart.

There have been reports of bad ground of the module, I took the time to run a separate ground wire to the mounting location.

If you get the module you to give you codes post them. Do you know ABS system you have. Can usually use key words to do a fault code search. I have several manuals that show ABS codes, in my case it is an Eaton system.

Tall Cowboy · 12-06-2021, 10:50 AM

Jim,
Many thanks to you and to others who replied to my post. I still don't know all I want to know about the ABS system but due to your replies, at least I got the ABS light to go off.
I removed the module and popped the button as you suggested. The contacts were clean. Apparently, the spring plate was weak and was keeping the light on constantly. I bent each tab to give it more spring action and break the connection. It seems to be ok now.
Once again, I want to thank you for your help and hope this thread will help others who may have the same problem