I had just watched that yesterday and was amazed at his patience in digging through the diagnosis

 

Managed to get my hands on a Scope. I just finished going over the wiring schematic to fully identify CAN bus paths, etc. Hopefully I will have time to get after this monster this weekend and report back.

 

While I have not yet had a chance to scope the LR3, I have driven it the past two days WITHOUT ANY HDC or other faults! What is different? I did not turn on the climate control. I will study that next since the climate control is throwing codes for all of the vent door actuators -- that all seem to work fine. The instrument cluster still shows U0132 and U0159 but the vehicle operates fine. Another thing-- the RPM does not surge as it has been doing Not sure if it will change with climate control on but I will wait another day before turning on climate control and comparing the two conditions. The transmission also shifts much better right now.

Last night I finally got the three amigos. I scanned the data streams from the modules and found something odd. The Vehicle Dynamic Control Module (ABS) data stream for steering angle was FROZEN at 763 degrees regardless of steering input. I then queried the steering angle sensor module itself and noted that it was displaying actual true steering angle data. I also found that the ride level control module was showing lateral acceleration at 276g's! If I turned the steering to the left or rightt while driving, it would go to 0g's or about 20g's but then back to 276g. Not sure if that is a problem as it was doing that well before the three amigos appeared. Recall that the Instrument Cluster has been showing U0132 and U0159 before and after the three amigos. After the three amigos, the ride level module reported U0416 as did the terrain control module. The ABS module also reported C1A00.




I turned off the car and turned it back on. The ABS module started at 756 degrees (while the steering angle sensor correctly displays a true 0 degrees). With steering input the ABS steering angle would respond but always return to 756 with the car going straight. WTH? Can someone query their LR3 and see if the steering angle module and ABS module show the same degrees? How could the ABS get so far off? This car things it is in a spin or something




I will use the scope this weekend to confirm things but it will only be helpful IF I catch the vehicle in the active error state with a CAN bus issue. What is interesting is the flow chart for the high speed CAN Bus. It starts with the instrument pack and a lateral to the steering angle sensor. The Instrument pack then connects to the ride level module then parking brake then rear diff (which has a lateral to the console switch) then SRS (which has a lateral to the speed control module) then ECM (which has a lateral to the transmission) then transfer case and finally the ABS module. The instrument pack and the ABS module both have 120 ohm resistors to form the ends of the BUS (when you measure the BUS it should read 60 ohms if it is good).

So, the steering angle sensor is literally at the opposite end of the BUS from the ABS. The sudden U0416 codes in the ride level and terrain modules both rat out the ABS module too. Based on the data now, I am thinking the ABS module is the primary fault that is causing the three amigos. The secondary fault that is NOT causing the three amigos is probably the instrument pack.




The medium speed bus issue with codes for all air door actuators reporting from the HVAC is probably the HVAC module OR the connections at the central junction box (Body Control Module) which I plan on pulling and inspecting for damage at a later date.

 

Played with the scope. Caught the high speed CAN bus frozen on the ABS unit. ALSO got HDC fault by engaging HDC on a hill. OBD Code C1A00. Ordering new ABS unit tonight. Also noted that the OBD triggered the brake switch faults and transmission faults

 

What do you mean by "Caught the high speed CAN bus frozen on the ABS unit"? Curious how you localized the fault to that hardware.

 

Frozen steering angle data from abs while steering module correctly reports 0 degrees

This is from the ride level module. 261g’s!!
Well, the first thing I noticed, while going through live data streams, was that the abs module was reporting a completely false steering angle compared to the actual position of the vehicle and the actual steering angle module data. Then, as soon as the amigos appeared, I noticed that the abs module data stream was displaying a false but now frozen steering angle. Turning the car off and back on unfroze the abs data. Next, i engaged the hdc and got immediate amigos. That is when we scoped the abs can. It seemed fine until hdc fault. That is when the abs can data stopped communicating. The abs pump also makes a horrendous noise for the second it activates.

this still does not address the u0132 or u0159 that report on the instrument cluster but those faults do not seem to effect drivability. It also does not address the faults reported on all climate control blend doors that work properly so that is going to be a ground, bcm or climate module issue.

 

Gotcha, so basically you correlated trouble on the canbus to when the ABS starting doing doing other strange stuff. Sounds reasonable, let us know how it turns out!

 

Here is the update:
1. Installed used ABS pump/module. That fixed the CAN BUS faults
2. Replaced the YAW module. No change to anything.
3. Ride Level Control Module still shows 261g's of lateral acceleration when car is standing still. Interestingly, if I turn the steering wheel ever so slightly while driving, it will go to 0g's until I head straight again. What have you folks seen on live data for this thing? I simply do not understand why the other modules report this correctly. Is there a program or ? to recalibrate this?
4. ABS still shows 780 degrees of steering angle even though steering angle module and other modules report correctly 0 degrees. I don't understand how two separate ABS modules report the same false data?? Anyone else dealt with this issue? Is there a program or ? to recalibrate this? The car still drives as if there is tons of oversteer! IF I disable DSC, it drives as advertised. I assume that the 261g's and 780degrees are really causing the oversteer issue.
5. I am still getting HDC Fault. If I run live data on EAS gallery pressure, I get about 25 psi in the morning and it quickly pumps to 245psi then leaks down to about 233 for a few minutes before dropping slowly to about 65psig. After a bit of time, HDC Fault and it lowers. I have been able to prevent the HDC Fault by hitting the raise button for a second and back to normal height as that triggers the compressor to fill back to 245psig before it turns off. Seems as long as I keep the pressure up, no HDC Fault! I am going to soap up the air system and look for leaks, etc. but that still does not address why the compressor does not turn itself on at about 230psig. Anyone experienced this issue?
6. Still have the P0741 code for TCC solenoid off. I have not had time to change fluid and solenoids but if that does not work, I can get an improved new torque converter for $150 from a buddy.
7. I went ahead and installed a new AGM H8 battery for the heck of it. Interestingly, the new batter cleared all of the Body Control Module faults that have always been present since we owned the car. The new battery had zero effect on any other issue.
8. I still get the U0132 and U0159 reporting from the Instrument Cluster but it does not seem to bother anything.

 

You're doing fantastic diagnostic work! What are you using to access OBD? Your program appears very advanced to what I'm using. My 2005 LR3 is having intermittent issues with the CAN BUS also with the common fault being the brake switch. I've changed it several times, it is not the issue. I will check the ABS BUS connections, hopefully they are the issue, we'll see.
Please let me know what you're using to access the OBD.

 

A bit of thread necromancy here...

Hoghammer, any recent updates on this? I have a similar issue and so I'm awaiting the outcome! =) Though it sounds like this fixed it because you posted a month later about the air suspension losing air... Makes it seem like it was drivable again! Or at least drivable enough that you just reboot the car and live with the gremlin (like I do!)

Wardo, I saw on another post of his it's iCarSoft that gives him the values. I have the Gap IID tool that can do the same thing though.