what is 'vehicle dynamics control module'

[ishekhar]

googled on it. the closest i could find was 'vehicle dynamics module' or VDM. but that was a dead end too.
Am getting U0122 (problem communicating to 'vehicle dynamics control module') in my 05 LR3.
took it to dealer who says need to replace this part.
wondering if this is something I can do it myself ?

[sideview]

Not sure but I think VDM might be a generic term, and Land Rover calls it DSC? What symptoms/lights is it having?

[ishekhar]

The car sometimes wont start at all. It shows all the warning sign as soon as i enter the key and do a first click. And then give up & wont' start. If i wait a few minutes and then try again, it starts.

Similarly, sometimes all the warning lights comes up while driving & i feel that vehicle has lost power; I generally pull over in such case, shutdown, wait and then restart . And then it restarts.

[sideview]

Strange that ABS/dynamic control type faults can cause start-up problems. Now the other way around - bad battery, alternator, wiring harness... are known to throw all sorts of faults in that respect, I dunno

[ishekhar]

BTW, any idea where is this DSC module located in LR3 (2005 model) ?

[Prodigy999]

the VDM and DSC are the same as the ABS module. The ABS module is located inside the modulator (valve block) under the hood. I wouldn't reccomend replacing it yourself as you need to bleed the brakes when you replace it (unless you are mechanically able).

[ishekhar]

Thanks Prodigy999. it seems to make sense because today I again got all the signs up and when I plugged in the Scanner, it threw:

U0121: lost communication with ABS module
U0122: lost communication with vehicle dynamics control module.

It seems to follow trend ie a couple of days ago, i first got 'HDC fault, system not available' but no code followed by all signs up and these two codes (U0121 & U0122) today. The same cycle happened twice before also. I disconnect the battery and everything goes away for a while. The battery test at Auto parts shop, showed nothing wrong with Battery as few posts suggested a possible defect point for 'HDC fault' warning light.

I am not an auto mechanic but would like to do whatever is easily doable & will definitely like to learn what's involved.

Do the above codes mean that ABS/DCM modules have really gone bad as my dealer suggests or they simply lost control at that point of time & that's it ?

[Prodigy999]

It's possible, however I have never seen one fail that way. What you need to check before you go any further is the all terrain ecu which is the switch pack on the center console (hdc switch, ride level selector, terrain rotary dial) Make sure nothing got spilled on it because that will kill the car and is a very common thing to happen. Most of the time it will look ok from the top but will have residue (usually coffee) on the bottom in the console.

Other than that 2005 models had electrical issues with the battery junction fuse box under the hood. The fuses would have bad contact with the sockets. You can check this with a pair of needle-nose pliers. Grab the fuse and one by one pull them out of the sockets and refit them. Compare how easily the fuse slides out to all the other fuses. If the fuse just falls out, then the problem lies within.

[Prodigy999]

By the way, what dealer have you been taking your LR3 to?

[ishekhar]

Thanks Again, i will refit fuses in the fuse junction box, will try to locate the switch pack, clean, inspect and changes if needed etc. and will share my results.

I have been taking my LR3 to Landrover in Cary, NC (USA).

thx again, you guys rock !!

[ishekhar]

refitted all the fuses in the fuse junction box. ran fine for couple of days but then the problem is back.

How do I open the 'switch pack on the center console' ? removed the rubber cup holders, the rubber pad, unscrewed one screw that i could see park brake switch & tried to pry open, but it wouldn't.