Air Compressor - Voltage Sag triggers VDM errors?

[TSY]

Out in Utah and went to air up after a week on trail - I put positive clip on the battery terminal and clipped the negative via frame (w/engine on). I didn't think much of it (simply because my last vehicle, the ground strap had a frame direct connection for this very purpose). Apparently on the Ford this is a no-no? After airing up - within 15 minutes I got Drive Fault error and Headlight Loss of Functions alert & the suspension has set the Fox shocks at the stiffest setting. (which absolutely sucked because I still had a couple of miles of dirt to navigate)

I'm assuming the compressor's noise caused a dynamics module to forget its reference heights. (?)

Anyone experienced this?

I'm headed to the dealer tomorrow to hopefully resolve the issue ....

... and yes - I have checked all of my ride height sensors and their respective plugs - all are physically good (insofar as I can tell anyway).

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[bigb]

You connected it properly, there is a battery management module attached to the negative post and you want to take current on the frame side of that, otherwise the BMS won't see the current flowing out of the battery and it won't know to tell the alternator to step up the pace.

Did you have the engine running when using the compressor? What compressor do you have and do you have the specs ie current draw and CFM at various pressures? Did you have a good, paint free connection on the frame? Maybe try the fender bolt right near the battery where the ground cable connects.

I'm using an ARB single connected to the factory ground cable. There a paint free stud with a nut on it right there you can use. Have not had an issue. Granted my ARB single is not that greedy on current, and I have stock tires so only a few minutes of run time to air up.

 

[bigb]

Here is the ground point I am referring to:

 

[TSY]

Ok - well thanks for making me feel ok about where I was connected etc!
Yes - Engine was running for all aspects of connection, fill up (power on) and power down and unclip. yes - I used that connection point...
So it's a SmittyBilt 2.54 cfm compressor, 30amp fuse (although I can't imagine it actually pulls that in a steady state?).

 

[bigb]

My ARB single draws up to 25 amps under load and is fused at 30 amps. I doubt yours is much different.

 

[TSY]

So it turns out the BCM (VDM?) is only getting 6V (instead of 12). Dealer shop is trying to track down the loss…

 

[bigb]

Doesn't make sense. I'm betting all you need is a new battery.

 

[TSY]

So it turns out - it's a whole lot of "non of these" things - Ford Engineering had the tech execute several test trees and the result is that my VDM power supply wire is not providing consistent load power. (enough at slack to pass, but under load it undervolts).

I'm not sure why now at 10k / 1 year later this defect is exposed ... but who knows. So far everyone from the engineering side has said the compressor attachment was a one-off / coincidence and not a contributor to the (assuming manufacturing) issue.

The solution provided from Ford engineering is to run a new independent power lead from a proven part of the loom direct to the VDM (spliced in at the connector).

Got the vehicle back yesterday - while I'm not entirely wild about running a jumper, the fix is holding.

lol - I intentionally ran down some heavily washboarded roads when I left the Ford dealership on my way home for beta. ( Read: Dust therapy. )

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