Location of VDC/VDU on 1999 Chieftain diesel

[drbkeele]

Freightliner tells me I have a VDC problem, but can anyone tell me where it is located? My rig is a 1999 Chieftain Diesel. I understand different motorhome manufactures put the VDC in different places.

[Skip426]

My VDC is in the engine bay and is identifiable by the 2 air lines that run into it along with electrical connectors. It's about 8" square and 1" thick. The post that describes the poor solder joints repair has pictures.
Search" VDC solder " in the Freightliner forums. For the PDF file the describes the repair.
Air gauge problems ?

[Skip426]

Quicker than the search in Freightliner.
Top of the web page , blue bar, to the right of " User CP" click " Files"
then " Electrical " then " VDU/VDC repair "for the download
Because the F/L wiring harness is long enough to allow manufactures some leeway in mounting the VDC they can be moved around , but the wire length limit is 2 feet. My VDC is on the passenger side of the engine bay mounted to the side wall , in a row with other controllers , rad fan, trans, low coolant, etc.

[drbkeele]

Thanks. Winnebago said it was mounted on the engine itself. That doesn't seem to make sense to me due to its function.

[Skip426]

Cat or Cummins ,the only electronics mounted to the engine is the Engine Control Module, because the ECM is supplied by the engine builder.
Do you need a picture ? or have you found one already?

[drbkeele]

Thanks. I ran into another problem. When I moved my winnie yesterday, the "Check Engine" light came on. Does the VDC/VDU control that too? I think I will go ahead and order a new VDU from Freightliner for $365 plus tax. I have a guy here in Arlington that will put it in for me at a very good price. I hope that also turns off the "Check Engine" light, but I'm guessing that it will not!
Again, thanks for the info.

[Skip426]

I'll check my wiring diagrams and see if I can track the data stream for the check engine light; to see if it routes through the VDC or is direct to the dash from the ECM. With multiple problems like your coming up with , might be worth while to look at all the wiring in the engine bay for possible rodent damage, and check all the wiring grounds, before you order any parts.
BTW. is your engine Cat or Cummins ?

[drbkeele]

Cummins 5.9. I decided to go ahead and pull the VDC and re-solder the joints. I can do that myself and hope to have it done by Saturday. Thank you so much for your extra effort. I'm not retired so don't have the time to do as much research as I would like.

[drbkeele]

I took the VDC out this afternoon and re-soldered the eight contacts for the air gauges. None of them were bright but were dull. After I finished with the 30 watt pencil solder iron, they were bright as they should be. I am replacing both elbow air hose connectors since I damaged one of them getting it disconnected. I cut both hoses since I was unable to get the old fittings to turn loose. New connectors were about $10.00 each. I'll reconnect tomorrow and see what results I get. On my Winne unit, the VDC was located in about the middle of the front part of the engine cover housing. I simply propped up the bed and the metal cover over the housing and easily undid the bolts. No rust. I have used a polymer sealant to re-seal the unit. I'll report results.

[Skip426]

Wiring schematics show the data link wiring from the ECM , routed through the VDC then to the gauges and dash info ( light bar ). So I hope your repair takes care of your check engine light.

[drbkeele]

Repair done and VDC replaced. Actually very easy. Started it. Built up full air capacity. No "check engine" light. Ran about 25 miles. Everything good. Thanks for the help AND the encouragement to go ahead and give it a try. Perhaps the repair will last as long or longer than the OM solder joints! Again--Thanks