Pretty sure the VDC unit in my 2003 Journey has the loose solder on the transducer problem. I'm in Phoenix now, and thinking there might be a good electronics shop here that could do the repair. Anyone have a recommendation?
Thanks Winterbagoal. I was aware that this has been a much discussed topic, and that there was guidance available here, Unfortunately I don't think I'm capable of doing it.
Location: Sarnialabad, Peoples Republik of Canuckistan
Posts: 1,251
No worries.
I probably wouldn't try it myself, unless the repair cost quotes were prohibitive. Then I might have a look at it, but I would weigh the risk/reward very carefully first.
I'm handy at some stuff, not so much at others.
DanMcC: Last summer I took my RV to Freightliner for a low air gauge concern. (Just 1 tank, not both.) Is this your problem or do you have other issues?
This location tried to bill be over $500 for the diagnosis and presented me with a $2,000 estimate to replace my gauge.
I said no thanks and paid the bill. Most of it anyway due to my concerns on if they checked the VDC or not. They said no they did not.
So off I drove, and when I got to my camp spot and had more time to research this subject, I found lots of good information on what the VDC is and what it does... and does NOT do.
I then took my VDC to a local TV-Electronics repair shop and for $50 they performed a professional repair to 8 soldier joints for each transducer. (Not 4 as sometime reported, because there are really 4-in and 4-out soldier points to make on the board.) So there are really 16 total soldier points.
The tech said he spent 20 minutes cleaning off the old resin coating and 2 minutes ADDING MORE SOLDIER to 8x2=16 cold-solder joints. Of course, only 1 or 2 joints probably needed the "reflow" to fixed the cracked joint, but you want to reflow all of them.
I also did not want to mess-up the board doing this myself since I have very little electronic repair experience using a soldiering iron.
As for that Freightliner shop who never heard of repairing a VDC, they refunded my money, but not without a lot of effort on my part. ...But I give the GM credit. His shop misdiagnosed the problem and so will many other Freightliner repair facilities who have never tackled this VDC problem that all but disappeared in 2005 when Freightliner moved the VDC functions to under the dash, where is is not subject to heat and vibration issue like it is in pre-2005 Diesel RVs. And they renamed the device MMDC, but it basically performs the same functions. (See diagram below.)
OTHER VDC REPAIR TIPS
* If you are leaking air out of an air line that connects to the VDC, sometimes all you need to do is to trim the end 1/16" to 1/32" and then reattach. Note: You might have to use several attempts to reseat the collar so air stops leaking. But if you don't hear or better yet "feel" air leaking out (wet your fingers), then changes are you just need to reflow those cold soldier joints to get your dash air gauge working again.
DIY == > $0 to repair. Thanks to other people on this forum who shared this information with me and now you!
Electronics repair shop fee ==> $40-$60.
* The VDC only has 4 nuts holding it in place. The hardest part is removing the red and green air hoses, but you can do that more easily by inserting an open-end wrench over the air line... and then applying leverage to that plastic retaining ring.
* After you open the VDC you will probably find the old sealant brittle and hard. ...Just leave it and when you replace the lid you can use RTV Silicon to re-seal it.
* When you remove the metal plate over the 2 transducers, don't lose 2 Teflon flat washers that just sit on top of the transducers. These things can stick to the plate or can get lost. ...You need these! ...And that metal plate holds these washers on top of the transducer.
Thanks imnprsd,
Especially interesting to hear that I'm not the only person who feels badly treated by a Freightliner dealership. They did settle on the VDC as the culprit, but spent way more time than I think reasonable to get there. Disappointing and expensive.
It is only the rear air gauge that acts up, and the symptom occurs seemingly randomly. I disconnected the alarm buzzer to preserve my sanity. But want to enable the alarm function soon. An interesting suggestion is to feel around the hoses with a wet finger to see whether it's a leak. That would be great. The other important message I see is that most electronics repair shops should be capable of effecting this repair. I'll also check that I have an in stock supplier for a new replacement unit, should thing go south.
My rear air tank was intermittent too, and it was not leaking air at the VDC. So my guess is that you have a 99% chance you can fix your problem buy following the suggestions by me and other owners when it comes to fixing those cold-soilder-joints, which again consists of just touching the soldier joint and re-heating the old soldier that is already there... after you remove the resin on top used for vibration protection. ...And over your new soldier joint the tip the TV-shop tech gave me was to seal it with a few drops of Super Glue!
So there is not real hurry to get this fixed, but you can easily do it outside the electronics shop or from your campsite if you have a tow car. Just make an appointment with the shop for a 30 minute quick TAT if they will let you, but my guess is that the shop will want you to drop off the VDC and then pick it up the next day. Of course, they will have never seen one of these things, so there will be no guarantee it will work, but so far 99% of us have successfully fixed this problem DIY.
If fact, I really would NOT expect Freightliner to fix a VDC; and the fact that most don't even know the VDC is mounts back by the engine is really not their fault since these things went out of production back in 2005 and most FL dealerships only work on motorhomes because they have to service the FL chassis.
That said, I am very glad there is a huge network of FL dealerships available to me when I am traveling. I just know they really charge a lot, but they do run a professional business and I like that.
Good luck with your repair and let us know how you make out?
Thanks again.
I'm starting to feel like I "should" try to do the fix myself. Here's an idea, I order a new unit from somewhere that accepts returns, don't open the packaging, and if I screw it up, I use the new unit, if not, I return it.
I certainly agree that it's comforting to know there's a FL facility nearby, and the one I visited also seemed very professional,
I sometimes forget (deliberately?) that I'm driving an 18 year old rig. It has implications.
Surprisingly, FL still carries my VDC and the price in 2020 was about $600. Further, I was surprised to learn FL has this his VDC in stock across the country, which suggests to me this VDC is used in other diesel applications besides RVs.
However, you need to verify FL still can provide you with the VDC for your chassis and model year coach as my VDC may be different than yours.
Note: The air line function is completely separate from the other functions. However, the VDC also shares a common power and ground with the ECM and uses the J1587 data bus to communicate with the Medallion instrument cluster too. (See previous diagram posted earlier.)
I theorize that these broken/cracked cold soldier joins may not only cause your gauge to read low or zero at times, it can also create some type of switching action (on-off-on) that looks like "noise" on the J1587 data bus.
...And consequently this explains why I feel my engine "ran better" after I fixed those cold-soldier-joints, however so miniscule.
I talked with FL about this subject on separate occasions and one tech said it is possible for anything on the J1587 bus that talks to the ECM can affect the performance of the ECM... and this includes all ECM engine sensors, which makes diagnosing a sensor problems sometime very difficult, because intermittent sensors do not often produce a fault code, and the same could be said for cold soldier joints in the VDC.
Anyway, if you fix your VDC yourself, more care will probably be spent cleaning off the protective resin coating on each soldier trace then it takes you time to reflow the soldier to fix the crack in the soldier joint. The trick may just require you to use a fine-tip solder iron... and you have to be very sure you do not have a solder bloom that shorts one pin to another pin.
Fixing those cold soldier joins has a high probability for success so I would not be bother ordering a new VDC in advance.
Thanks, Every bit of information helps.
Is there a suggested method for removing the resin on the solder?
My gauge more often flips to the maximum level. Though it sometimes drops to zero. I've also seen it swing back and forth for a bit of time.
the idea that this data could influence the ECM does add some urgency to getting it taken care of.
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