Hey Y'all! I purchased a 2006 LR3 SE with 188,000 miles on it so I am not expecting greatness out of it. The HDC fault kept coming on before starting the LR3 then stayed on following. When I bought the LR3 it was not on, but came on shortly after on the ride home. I came to y'all's great site and began researching and attempting to fix the issue. Here are the steps I took to attempt to resolve the issue:

1. Replaced brake light switch
2. Checked bulbs
3. Cleaned connections under special programs rotary ****
4. Pulled trim and checked groundings and wires for wear/corrosion
5. Replaced battery
6. Re-flashed computer with suspension update disabling EAS features because I have the Atlantic British coil conversion

My HDC fault used to show up immediately, but after the above steps it shows up after 3-4 minutes of driving, sometimes not at all. I drove 10 minutes with no lights or A/C thinking it could be a voltage issue and the HDC fault did not occur. I then restarted the LR3 turned all the lights on, turned the A/C on, and turned the heated seats on. The HDC fault showed up about 3-4 minutes into driving and coincidentally right as I hit the brakes the first time. I love a good puzzle, but this one has me stumped. I am thinking it is a voltage issue and possibly a brake light bulb issue as I did not check to see if they were OEM bulbs. Does anyone have any suggestions on what to do? I searched and searched and have not tried changing the transmission control module or alternator yet.

All help is appreciated. Thanks!

 

Need the code for the faults, there are endless reasons why it can fail since almost any subsystem can cause it to go offline. Basically an HDC fault does not always mean there is actually an HDC fault, but instead a system that renders it unsafe to use. Certainly check operating voltage with a meter at the very least. Also consider obscure things like bad ABS sensor or bad wheel bearing (which throws off ABS sensor readings). But you really need the codes more than anything.

 

And you don't need oem bulbs, just quality ones.Was the brake switch a genuine or Ford branded item or generic ?

 

Thanks y'all!

DakotaTraveler I will get the codes tonight. I am not showing any ABS warning lights, but that does not mean it is not the culprit.

loanrangie, the brake switch I replaced was from Ford. The new one is generic. I am not under the impression it is the brake light switch. I took it to the country last night to mess around in some mud. The system worked intermittently, but did not seem to turn off or on based on braking input. I think I am going to bite the bullet and grab a GAP tool.

Not sure if this information helps, but the LR3 only starts on the second attempt every time I go to drive it. The only exception to that rule was when I ran the battery out by accident and jumped it with my wife's car. When I jumped the LR3 it started immediately with no delay. I initially thought I had a fuel delivery system issue with the fuel pump perhaps not getting gas to the motor fast enough at startup, but after starting it immediately with the jump I am thinking it is an electrical issue. Who knows? Another day another puzzle.

 

You said in #5 that you replaced the battery. Was that after you drained the battery? Is it still not starting with the new battery?

This does seem voltage-related to me. In both of my LR3s, I had the engine running and the INSTANT I plugged in my IIDTool, I got an HDC fault; however, it didn't even show up in the IIDTool search for faults nor could I clear it. It was like a phantom soft fault. I cycled the ignition and voila, gone.

I contacted GAP about that and they advised me to only insert the tool with the key in the "ON" position (I guess that's pos II) and not with the engine running. Curious....but the morale of the story is that weird voltage dips can cause phantom HDC faults.

 

Just a little update. I was spooling out the cable on my CJ5's winch when its battery was running low. I had to jump the CJ5 with the LR3. I left both running for about ten minutes while connected. After disconnecting the CJ5 from the LR3 I have yet to get an HDC fault. That was about 5 days ago. My theory is that the LR3's new battery was not fully charged/up to 12V when I bought it. I also bought a cigarette lighter voltmeter so I could read the voltage before starting and after starting. Before the CJ5 incident, my voltage was around 11.4 while doing the system check before starting the LR3, thereby throwing the HDC fault. After the incident it is now 12.2-12.5 before starting, so battery only. When I turn the LR3 on the voltage reads 13.5-14.4 (higher on cold days, lower on hot ones, South Carolina's climate fluctuates far too much). I have concluded it was more than likely a voltage issue. Whether the cause was the solely the battery, I do not know!

I do appreciate all of y'all's input and help! I am still throwing code P0504 (brake light switch) with the new switch and old one. No HDC faults, cruise control is working, and special programs are working.

 

Probably coincidence but you may have just had a low battery. It take longer than 10 minutes to recover a battery from a jump. Plus at idle there is voltage, but not a lot of available amperage. Batteries take a while time to recover at idle. To recover a dead battery, one that needed a jump, take at least an hour of driving. Also if you are using the infomat system to check voltage in the LR3 when not running, well its not at all a reliable number. Voltage with the infomat should only be checked when running. When the key is in position II every computer is running causing a substantial power draw, which will give a very low number.

 

...what about when you charge the battery from a (trickle) charger? Even after it says 100%, should I keep it on for an hour or more? Often it will be around 12.1 or 12.2 volts after sitting for 8-10 days. I'll put the charger on it and within 10 minutes it's at 100V (and 14+ V)...but should I leave it on longer???

 

You should read up on how batteries charge, etc. 10 minutes will not charge crap, the voltage reading is not settled yet.

 

...glad I asked. Sheesh, have a beer, Dakota!!!

Thank you, though, for the feedback. 😁 You are of course totally correct. I charged that bad boy up yesterday for about 6-8 hours. The charger showed 100% charge and was no longer actively charging. In the past, it would show maybe 95% and if I hit the "charge" button it would toggle on, immediately show 100% but then after a few seconds start decrementing. It is not the most intuitive interface or feedback, but bottom line I wasn't leaving it on long enough and only giving the battery a partial charge. Hopefully I didn't hurt anything....it is an AGM battery and not very old, so I figure it should be okay. Lesson learned.