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2007 SC xmas tree special programs off/trans/brake/hdc/etc

3K views 11 replies 2 participants last post by  RoverGuy7 
#1 ·
Plus heavy steering. Happened 3 times inside a couple of days. Battery? Reading 12.00 so I'm assuming it's about done especially since it just started getting cool out... Seems good with the generator spinning 14.7X. Just curious if there is a known problem like the LR's with that brake pedal switch going bad causing the xmas tree. Battery is getting replaced tonight regardless. I pulled codes and it seems like the entire canbus goes down. Heaving steering related to the steering angle sensor going off line/no power assist?


TIA

~Brad
 
#2 ·
I'd deffinetly get the battery charged up, if not replaced, but not sure this is your main issue.

Is the suspension lowered?

Check engine light on?

Any exact messages/fault codes will help here. Considering it's SC, I'm going to lean towards rear diff motor, but that will drop the suspension. What P and C codes do you have? Focus on those before worrying about the U codes, as any real fault will cause communications/invalid date faults.

Steering default with a lot of major issues is to go heavy, it's safer than full assist at higher speeds.
 
#3 ·
This only happened a few times on the highway so far, so if it reoccurs after battery replacement I guess I'll just datalog until the fault trips again and see what faulted first. When I pulled codes after the fact it was basically everything, even the radio resets... Basically scrolling through the faults various things lose sync. The suspension isn't physically dropping, during the fault I have no control. Restarting the car is a remedy.

I guess if this isn't a fix I'll look closer at the rear diff motor...

good to see you're still posting, as always the advice is greatly appreciated!
 
#4 ·
I'm going to assume the rear diff motor would be the noise when you power down the range, you can hear it locking? Is that right? Before the battery change I'd power down the range and noticed after you mentioned the rear diff motor that noise had stopped happening. New battery in and just went roughly 60 miles no error and that noise is once again obvious when powering down.
 
#5 ·
Most likely, but I believe it defaults to full unlock at shutdown.

This failure is usually a hard fault, and doesn't just fix itself, and low voltage can cause it to not fully go through it's self-test at startup, so maybe the new battery is all the fix you needed, just had everything shutting down due to the diff motor faulting out.

Keep an ear out for the noise, I've noticed the louder they get, the closer to failure they are.
 
#6 ·
The car was fine for a week after new battery etc... Now completely randomly I get limited gears message, sometimes xmas tree, intermittently the warning for the adaptive lights comes on... I pull codes and it seems everything loses canbus connection. Even the radio skips a beat sometimes. Maybe a bad ground or something? When I go to pull codes basically everything has faulted... Going into the rear diff menu, or any menu for that matter yields voltage too low, too high, lost connection, software incompatibility. Not sure what the issue could be, anyplace I should look? Maybe corrosion at some computer harness?

thanks guys!
 
#7 ·
I'll also add it seems like an electrical hiccup at various times... sometimes I start the car and moments later it's xmas tree, sometimes no issue at all... Almost everytime I drive the car it seems there is loss of electrical power, the radio hiccups (screen flashes) I also noticed when this happens if the heated steering wheel is on, it goes off, but then refuses to come back on. Thinking a ground or electrical contact somewhere but a little lost as to where. The battery is new, and I'm getting 14.8 with the car running so the alt seems good. Sort of at a loss.

Thanks again
 
#8 ·
You might be looking at an overcharging situation, monitor battery voltage while driving, and hopefully you'll see something next time it triggers(I hook up a meter to the power outlet, but even using the display in the nav menus will work)

These vehicles don't have many grounding issues, but I've replaced many alternators that can test out fine, but fail intermittently.
 
#9 ·
Per your advice I put it to live voltage data on the scanner. I cleaned all the battery terminals etc etc, started the car, no problems at idle... Gave it some load and volts go from 12-13 to 17 then everything faulted... Basically every system was faulting across the display parking brake/lights/hdc I could hear locking motors going back and forth, limited gears trans fault etc etc etc.

Now it does this everytime I start it at varying degrees of severity. Shotgun the issue with another alternator?
 
#10 ·
now I got check engine, everything in the car goes completely haywire on start. I pulled a generic scanner up just to see what that says... tons of faults the first being, "system voltage too high," maybe the alternator I just put in has a bad voltage regulator... As I said before I was seeing it spike up to 17v while just idling in the driveway.
 
#11 ·
new alternator fit... 50 miles on the car and no issues yet. Datalogged volts and it seems stuck right at 14.2-4 so pretty sure this was the issue considering I was seeing spikes with the old alt.

Also the old alt looked scorched pretty much everywhere... The voltage regulator itself was mostly black so hopefully this was the issue, sure seems like it.

Thanks again with the diagnostic help Dave.
 
#12 ·
Good stuff, yeah, there isn't much else that will cause it to overcharge, I could come up with a scenario, but several different things would need to fail in just the right ways. And yeah, these alternators do go out, I usually start to see more issues with them as the weather changes.
 
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