Gents,
I've searched and read many issues regarding the old "VDC" units and the newer MMDC units. I'm thinking I may have developed an MMDC issue. Here's the scenario. We're presently on vacation and all has been going well. We were on the freeway, I-10E, just outside of Lordsburg NM when all of a sudden, the speedo started dropping. I had the cruise set to 60. The speedo started dropping, stumbled a bit, then fell to zero.
The rig was corresponding to that too. In other words, the cruise had been shut down. Along with that, the tach went to zero, the oil pressure, water temp, turbo boost, and voltage gauges, all died. I think the air pressure gauges for both front and rear are still operative but, I can't remember (we're camped in Silver City NM right now). Another problem, and a serious one, the exhaust brake QUIT!
And, on my annunciator panel, the "ABS" has lit up, and "Check info center" is also lit up. When I look at the Medallion Info Center, it's reading "No data from Trans ECM and NO DATA from Engine ECM for 25 seconds", and is flashing that over and over.
Now, with all this going on, here's the deal. The engine is still running like a top. The trans is still shifting and operating flawlessly. All the lights, turn signals, brake lights and most other normal electrical stuff is still working just fine. And, I also have what's known as the "Trip-Tek" computer on board too. And, to those of you that don't know what that is, or don't have it, it's a system by which additional information, engine stats, trip odometer(s), maintenance items and more, are displayed on the monitor of the back up camera.
Well, since I lost all important gauges, I hit the Trip-Tek and all the engine stats, oil pressure, engine temp, trans temp, etc. are still just fine and operating just fine. My fuel gauge is working just fine.
Well, I pulled off the road, into town, and got lunch. Then we pulled the rig onto a side street and I called Freightliner help. They started to direct me to the MMDC 10-pin plug. They say those pins can get damaged due to the weight of the harness(s) in that area that tugging away at the plug. My phone was acting up too so I was in an out of the conversation with the Freightliner tech so, I thanked him for his time and went out and pulled that 10 pin plug and looked at it.
It looked just fine to me. Now, I also talked with my son, who works as an RV tech in San Diego and he has replaced many MMDCs due to faulty soldering on and in the pc board inside them. That's the same issues the older VDC units were having. What's up with these boys that do these boards? Anyway, to those who've had issues with the later MMDC units, did you have the same or close to the same symptoms? Is there a way to tell if the MMDC is actually bad without taking a chance on $400 or $500 worth of experimenting?
As stated, my speedo quit and so did my odometer. Now, to me, that's kind borderline "illegal" isn't it? I mean, heck you could drive that thing for another 100K miles and then get it fixed and, sell it as a "lesser mileage" vehicle". But, that's beside the points here. I sure could use some help here.
Scott
I've searched and read many issues regarding the old "VDC" units and the newer MMDC units. I'm thinking I may have developed an MMDC issue. Here's the scenario. We're presently on vacation and all has been going well. We were on the freeway, I-10E, just outside of Lordsburg NM when all of a sudden, the speedo started dropping. I had the cruise set to 60. The speedo started dropping, stumbled a bit, then fell to zero.
The rig was corresponding to that too. In other words, the cruise had been shut down. Along with that, the tach went to zero, the oil pressure, water temp, turbo boost, and voltage gauges, all died. I think the air pressure gauges for both front and rear are still operative but, I can't remember (we're camped in Silver City NM right now). Another problem, and a serious one, the exhaust brake QUIT!
And, on my annunciator panel, the "ABS" has lit up, and "Check info center" is also lit up. When I look at the Medallion Info Center, it's reading "No data from Trans ECM and NO DATA from Engine ECM for 25 seconds", and is flashing that over and over.
Now, with all this going on, here's the deal. The engine is still running like a top. The trans is still shifting and operating flawlessly. All the lights, turn signals, brake lights and most other normal electrical stuff is still working just fine. And, I also have what's known as the "Trip-Tek" computer on board too. And, to those of you that don't know what that is, or don't have it, it's a system by which additional information, engine stats, trip odometer(s), maintenance items and more, are displayed on the monitor of the back up camera.
Well, since I lost all important gauges, I hit the Trip-Tek and all the engine stats, oil pressure, engine temp, trans temp, etc. are still just fine and operating just fine. My fuel gauge is working just fine.
Well, I pulled off the road, into town, and got lunch. Then we pulled the rig onto a side street and I called Freightliner help. They started to direct me to the MMDC 10-pin plug. They say those pins can get damaged due to the weight of the harness(s) in that area that tugging away at the plug. My phone was acting up too so I was in an out of the conversation with the Freightliner tech so, I thanked him for his time and went out and pulled that 10 pin plug and looked at it.
It looked just fine to me. Now, I also talked with my son, who works as an RV tech in San Diego and he has replaced many MMDCs due to faulty soldering on and in the pc board inside them. That's the same issues the older VDC units were having. What's up with these boys that do these boards? Anyway, to those who've had issues with the later MMDC units, did you have the same or close to the same symptoms? Is there a way to tell if the MMDC is actually bad without taking a chance on $400 or $500 worth of experimenting?
As stated, my speedo quit and so did my odometer. Now, to me, that's kind borderline "illegal" isn't it? I mean, heck you could drive that thing for another 100K miles and then get it fixed and, sell it as a "lesser mileage" vehicle". But, that's beside the points here. I sure could use some help here.
Scott
Thanks for posting the cure. I think you're like a bulldog when you've got a problem to solve. I enjoy reading your posts.
Fred
Fred,
I chuckled on that one. "Bulldog" huh? That's funny. As I've stated many time before, I do almost all my own work for many reasons. Probably the same ones most of you do it for. One, to save money, two, to "hopefully" do the job correct, three, to learn more about my (our) rig, and four, if I post here about what I've done, (right or wrong), maybe some one can benefit from my trials and tribulations.
dougmac,
Yes Sir, the J1939 is quite a system. But, in all reality, it's actually very simple to me. It's two wires and two resistors. It simply transports info, to and from, all concerned parties that are attached to it. Even though I've only done one in my life time, to me, it's the same thing as a "Conference call". All parties get to speak, at the same time. They get to voice their opinions, ask questions and get results, all on two wires. Until two weeks ago, I had no idea it, the J1939, existed.
Since then, I've learned quite a bit about it and, there's also two more data links in that system. One is the 1587 and the other is the 339D. As I understand the principle operations of the 1587, it's simply a data link, a very slow speed one at that, around 96 BIT, between the Engine ECM and the Trans ECM. That's why the engine and transmission could "talk" with each other while the J1939 system was down.
As for the 339D system, as far as I can tell, it's a small data link that's intended for only two components. One, the MMDC and the other, the Information Center. That data link is what is used to display info on the information center. This stuff is cool.
Scott
Fred
Fred,
I chuckled on that one. "Bulldog" huh? That's funny. As I've stated many time before, I do almost all my own work for many reasons. Probably the same ones most of you do it for. One, to save money, two, to "hopefully" do the job correct, three, to learn more about my (our) rig, and four, if I post here about what I've done, (right or wrong), maybe some one can benefit from my trials and tribulations.
dougmac,
Yes Sir, the J1939 is quite a system. But, in all reality, it's actually very simple to me. It's two wires and two resistors. It simply transports info, to and from, all concerned parties that are attached to it. Even though I've only done one in my life time, to me, it's the same thing as a "Conference call". All parties get to speak, at the same time. They get to voice their opinions, ask questions and get results, all on two wires. Until two weeks ago, I had no idea it, the J1939, existed.
Since then, I've learned quite a bit about it and, there's also two more data links in that system. One is the 1587 and the other is the 339D. As I understand the principle operations of the 1587, it's simply a data link, a very slow speed one at that, around 96 BIT, between the Engine ECM and the Trans ECM. That's why the engine and transmission could "talk" with each other while the J1939 system was down.
As for the 339D system, as far as I can tell, it's a small data link that's intended for only two components. One, the MMDC and the other, the Information Center. That data link is what is used to display info on the information center. This stuff is cool.
Scott
Well Gang,
To anyone who cares, the problem has been fixed. A very long story short. It was exactly what I thought it was. A broken wire/bad contact pin, in one of the three wires that make up the J1939 Data link. It was the green one. A very strange situation if I must say so. After lots of investigation, unplugging connectors, checking resistance, continuity and general condition of all the connectors involved in the J1939 data link.
Well, with a bit of help, the engine was running and I was at the helm watching the gauges. My son was under the coach, tweaking and wiggling wires. Eventually he found the problem area. I shut down the engine and got under there with him. He pointed out the general spot. I got under there the next day and went to work on trying to find and pinpoint the exact spot. It was very tough. I eventually narrowed it down to a connector or, an inch or two in either direction of it. I ended up braking part of the connector so, I finished the job.
What I found was, a broken green wire right where it enters the back side of one of the pins. The Yellow and black one was perfect. I ruled out the thought about stress on the wire(s). If that was the case, then why didn't the yellow and black ones break also???? So, what I figured was the original installer just goofed up when stripping the green wire and cut it too deep and cut off most of the strands of the copper wire too. It took 49,000 miles to vibrate/break off the rest.
So, I cut off the entire connector and installed a Weather Pack one and all is back to normal. All my gauges work as they are supposed to. So, I hope this never happens to anyone of you, it's a severe pain in the a$$ hunt down and trace the broken section.
Scott
To anyone who cares, the problem has been fixed. A very long story short. It was exactly what I thought it was. A broken wire/bad contact pin, in one of the three wires that make up the J1939 Data link. It was the green one. A very strange situation if I must say so. After lots of investigation, unplugging connectors, checking resistance, continuity and general condition of all the connectors involved in the J1939 data link.
Well, with a bit of help, the engine was running and I was at the helm watching the gauges. My son was under the coach, tweaking and wiggling wires. Eventually he found the problem area. I shut down the engine and got under there with him. He pointed out the general spot. I got under there the next day and went to work on trying to find and pinpoint the exact spot. It was very tough. I eventually narrowed it down to a connector or, an inch or two in either direction of it. I ended up braking part of the connector so, I finished the job.
What I found was, a broken green wire right where it enters the back side of one of the pins. The Yellow and black one was perfect. I ruled out the thought about stress on the wire(s). If that was the case, then why didn't the yellow and black ones break also???? So, what I figured was the original installer just goofed up when stripping the green wire and cut it too deep and cut off most of the strands of the copper wire too. It took 49,000 miles to vibrate/break off the rest.
So, I cut off the entire connector and installed a Weather Pack one and all is back to normal. All my gauges work as they are supposed to. So, I hope this never happens to anyone of you, it's a severe pain in the a$$ hunt down and trace the broken section.
Scott
dougmac,
Well Sir, so far, I've done some tests that have indicated that the terminating resistors, each 120 ohms, are both intact and in good shape. But, based on the test procedures, when I test the correct pins in the diagnostic ports, on each end of the coach, I'm getting a "119-120" ohm reading on each end. According to the results I'm getting, the J1939 is OPEN. The readings I'm supposed to get from the two pins is 60 ohms. So, now it's simply going to be the painstaking, methodical tracing of the J1939 data link, all the way down the frame etc. The MMDC, and it's connections, pin testing etc. are all just fine.
Scott
Well Sir, so far, I've done some tests that have indicated that the terminating resistors, each 120 ohms, are both intact and in good shape. But, based on the test procedures, when I test the correct pins in the diagnostic ports, on each end of the coach, I'm getting a "119-120" ohm reading on each end. According to the results I'm getting, the J1939 is OPEN. The readings I'm supposed to get from the two pins is 60 ohms. So, now it's simply going to be the painstaking, methodical tracing of the J1939 data link, all the way down the frame etc. The MMDC, and it's connections, pin testing etc. are all just fine.
Scott
Dougmac,
Sorry for the late reply. The last couple of days we've been on the road, on the way home, and camped where there was no I-net. So, we're home now. My rig is in it's parking spot, under the cover, on concrete and, ready to be analyzed.
This is going to be all new to me. I've not had to do any type of searching for problems like this before. There's only about a thousand miles of wiring in that coach and, almost all of it inside that PIA corrugated plastic loom. Nice for protection and segregation but, a pain when trying to trace wiring. Now, you say the "engine and trans are communicating fine"? With what?? The medallion info center that receives all that type of stuff still says "Engine ECM and Trans ECM no data. But, maybe you mean they're talking to each other and working good together 'cause the rig is still running down the road fine, just no data being sent to the speedo, tach and other gauges.
Scott
Sorry for the late reply. The last couple of days we've been on the road, on the way home, and camped where there was no I-net. So, we're home now. My rig is in it's parking spot, under the cover, on concrete and, ready to be analyzed.
This is going to be all new to me. I've not had to do any type of searching for problems like this before. There's only about a thousand miles of wiring in that coach and, almost all of it inside that PIA corrugated plastic loom. Nice for protection and segregation but, a pain when trying to trace wiring. Now, you say the "engine and trans are communicating fine"? With what?? The medallion info center that receives all that type of stuff still says "Engine ECM and Trans ECM no data. But, maybe you mean they're talking to each other and working good together 'cause the rig is still running down the road fine, just no data being sent to the speedo, tach and other gauges.
Scott
Dougmac,
Well Sir, let me put it to you this way. While the tech was looking and looking for the two resistors, AM I'M PAYING FOR HIS TIME, I thought I'd do something that makes sense, CALL FREIGHTLINER CUSTOMER SERVICE!!!! So, I called, told them my vin, and my issues and they told me right where the two resistors are. The first, as stated, is just down a few inches from the rear diagnostic port.
And the man on the phone also told me that the other one was "In the MMDC". I confirmed what he said and, he said yep, it's inside the MMDC.
That phone call took all of two and a half minutes. Well, I jumped out of the car and ran (fast walk) over to the tech. I told him what I found out. He said he'd found the one at the rear but was not aware of the other one being "inside" the MMDC. So, he ran some sort of checks and said that yep, it's not answering his probe tests the way it should so, they ordered up, a new MMDC from Memphis. It was air freighted in and, the installed it at about 3:00 today.
Well, guess what, that did not cure my issues. And, talking with some of the other techs there at the Freightliner Service Center, and they said that they've NEVER HEARD OF THE END RESISTOR BEING inside the MMDC.
So, now I'm stuck. I told the service center that since the new MMDC did not work, I was not going to pay for it, and, they wanted me to stay one more night in this rat hole of El Paso and I made the decision right then and said "nope" "Wrap it up" I'm leaving with it still malfunctioning.
That Freightliner Service Center "On the Border Freightliner" is by far, the worst operating repair center I've ever had to deal with. While there, the wife and I talked with other RV owners and, several over the road truck drivers and they all agreed, it's one of the worst Freightliner Service Centers in the U.S. Absolute horrible people skills/communication skills, phenomenally slow in every phase of an encounter with a customer, from the start, through the analyzation process, repair process and realllllllllly slow in wrapping up all the paper work.
What a nightmare. We will never, ever go anywhere near that town again.
Anyway, so, after that much rambling, I'm here, at a much nicer camp ground, in Las Cruses NM and, it's quieter, cleaner, and way more civilized. But, I'm still broke. No speedo, no tach, no water, oil, volt and turbo boost gauges. No cruise control and or exhaust brake. The coach is operating just fine. I will do some attempting to check connections etc. while we're out traveling. So, we'll see. Thanks again.
Scott
Well Sir, let me put it to you this way. While the tech was looking and looking for the two resistors, AM I'M PAYING FOR HIS TIME, I thought I'd do something that makes sense, CALL FREIGHTLINER CUSTOMER SERVICE!!!! So, I called, told them my vin, and my issues and they told me right where the two resistors are. The first, as stated, is just down a few inches from the rear diagnostic port.
And the man on the phone also told me that the other one was "In the MMDC". I confirmed what he said and, he said yep, it's inside the MMDC.
That phone call took all of two and a half minutes. Well, I jumped out of the car and ran (fast walk) over to the tech. I told him what I found out. He said he'd found the one at the rear but was not aware of the other one being "inside" the MMDC. So, he ran some sort of checks and said that yep, it's not answering his probe tests the way it should so, they ordered up, a new MMDC from Memphis. It was air freighted in and, the installed it at about 3:00 today.
Well, guess what, that did not cure my issues. And, talking with some of the other techs there at the Freightliner Service Center, and they said that they've NEVER HEARD OF THE END RESISTOR BEING inside the MMDC.
So, now I'm stuck. I told the service center that since the new MMDC did not work, I was not going to pay for it, and, they wanted me to stay one more night in this rat hole of El Paso and I made the decision right then and said "nope" "Wrap it up" I'm leaving with it still malfunctioning.
That Freightliner Service Center "On the Border Freightliner" is by far, the worst operating repair center I've ever had to deal with. While there, the wife and I talked with other RV owners and, several over the road truck drivers and they all agreed, it's one of the worst Freightliner Service Centers in the U.S. Absolute horrible people skills/communication skills, phenomenally slow in every phase of an encounter with a customer, from the start, through the analyzation process, repair process and realllllllllly slow in wrapping up all the paper work.
What a nightmare. We will never, ever go anywhere near that town again.
Anyway, so, after that much rambling, I'm here, at a much nicer camp ground, in Las Cruses NM and, it's quieter, cleaner, and way more civilized. But, I'm still broke. No speedo, no tach, no water, oil, volt and turbo boost gauges. No cruise control and or exhaust brake. The coach is operating just fine. I will do some attempting to check connections etc. while we're out traveling. So, we'll see. Thanks again.
Scott
"If you could identify the pins on the connector that the wires go to you can see if you have a good connection to the data link by checking the resistance between the two pins. If it is around 60 ohms, you have a good connection to the data link. You want to be sure the other controllers connected to the data link are shut down when you are testing."
Dougmac,
I most certainly appreciate your assisting me with this issue and "coaching" me on some test procedures. If I were at home, I'd have dove into this with both feet. That way, if I screwed something up, we wouldn't be stuck some place in "Nowheresville" and then have to get tow, and all that stuff.
In the time we've owned this coach, I've taken the time to read and learn about the innerds of this beast as much as possible. Some stuff is easy to comprehend. Some, you almost have to be a "Suma com laud" from MIT to grasp the concepts.
Computers have done well in making todays autos a more better, safer and more efficient machine but, they've also made them SERIOUSLY MORE COMPLICATED in terms of searching out problems.
One of the things I learned yesterday was, there's two resistors in the J1939 data link. One is accessed just down line from the rear diagnostic port, just above the radiator. The other, is located INSIDE the MMDC.
Now if this isn't one of the most asinine things done in auto technology, I don't know what is. You see, that little, "$.50" resistor, is INSIDE a $400.00 computer. So, when that little fifty cent resistor goes bad, you get to spend $400.00 and, pay to have it replaced when, I can have that MMDC out of my coach in right at 2 minutes.
But, since I was/and still am, somewhat limited in diagnostic capabilities, I/we the DW and I, are going to take the shaft when it gets replaced today. So, live and learn. And some people wonder why I still change my own oil.
Scott
Dougmac,
I most certainly appreciate your assisting me with this issue and "coaching" me on some test procedures. If I were at home, I'd have dove into this with both feet. That way, if I screwed something up, we wouldn't be stuck some place in "Nowheresville" and then have to get tow, and all that stuff.
In the time we've owned this coach, I've taken the time to read and learn about the innerds of this beast as much as possible. Some stuff is easy to comprehend. Some, you almost have to be a "Suma com laud" from MIT to grasp the concepts.
Computers have done well in making todays autos a more better, safer and more efficient machine but, they've also made them SERIOUSLY MORE COMPLICATED in terms of searching out problems.
One of the things I learned yesterday was, there's two resistors in the J1939 data link. One is accessed just down line from the rear diagnostic port, just above the radiator. The other, is located INSIDE the MMDC.
Now if this isn't one of the most asinine things done in auto technology, I don't know what is. You see, that little, "$.50" resistor, is INSIDE a $400.00 computer. So, when that little fifty cent resistor goes bad, you get to spend $400.00 and, pay to have it replaced when, I can have that MMDC out of my coach in right at 2 minutes.
But, since I was/and still am, somewhat limited in diagnostic capabilities, I/we the DW and I, are going to take the shaft when it gets replaced today. So, live and learn. And some people wonder why I still change my own oil.
Scott
