Zero point calibration not working (1 Viewer)

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Joined
Nov 22, 2020
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Location
Indiana
someone has to have some insight on why my 2004 gx470, simply will not take a zero point calibration. I started a thread on this issue a few months ago with no avail, frustrating as I’m sure I’m not the only one who’s had this issue. Super long story short, had a new reman rack installed and now am getting the vsc kicking on when cornering as well as when stopping on an incline and letting the car roll backwards while in drive. The vsc light will come on and beep and the abs will engage. I’ve had it to the local Toyota dealer twice as well as the not so local Lexus dealer. They do a zpc and a quick test drive, no issues and codes thrown, they call me and say it’s fixed. I get the car drive home, find a hill and let the car roll backwards, vsc light and abs kicks on as before. What the hell? No issues at all before the new rack, there are no sensors in the rack so don’t think it’s a problem there. What could it be? Upon startup steering angle shows 1150 until you drive for a short bit, hence showing the steering angle is not calibrated. What am I missing? Any help out there is appreciated. I’ve done everything I possibly can. There are no active dtc codes with the vehicle
 
Did you read the code?
There are report on one GX460 a couple years ago

Here is the excerpt
Wanted to share my recent experience fixing the traction warning light that would not turn off on my 2011 GX460. Very long (and probably boring) post ahead, but hopefully it will help someone in the future (and trigger warning for anyone that has ever been fiscally abused by your Lexus dealer).

About a year ago I had all four brakes and rotors replaced, new tires mounted, and had an alignment done by my local brake/tire shop. After picking the GX up I saw the traction light on. Took it back to the shop and long story short, after three trips, and them having it for hours, they gave up and told me to drop it off and they would take it to the dealer for me. Well life and COVID happened and never did take it back there.

Over the next year, I had other stuff done at different shops, and none could turn the light off. I also posted about it here and everyone recommended I do the Zero Point Calibration, but that had been done by two separate shops already and didn't help (yes, as you will read, you were all correct).

Fast foward to this month and I make an appointment at my local Lexus dealer for a recall notice. I drop it off and have them look at the light. They said no problem, but it is going to be $220 for diagnosis fee. Figuring I would have the local shop pick up the tab afterwards, I agree.

Service guy calls me and said it's bad news. Their "master" tech took a look, did the ZPC multiple times, checked every single ABS sensor, wheel sensor, wires, etc. and the problem must be some serious electrical short or other major issue. After spending 4 hours on it service guy says they can't do anymore free diagnostic work and will need to charge me about $700 for 3 more diagnostic hours. But not to worry, that money will go towards the repairs it most definitely needs.

Of course I told them to go pound sand, paid my $220 fee for nothing, and drove home. It just didn't sit well with me. What are the odds something just broke at the exact same time? The only thing they were able to do is to pull a code for me: C120A. So I just google that and what came up was in reference to the Master Solenoid not recognizing the Downhill Assist. And tons of people talking about this happening after an alignment on 4Runners and GXs. So what is the fix: do the Zero Point Calibration.

But hey, the ZPC had been done. By three shops at this point. Multiple times. And even by a master Lexus tech. So I google some more and find the PDF for doing the ZPC, and there are five steps. Steps 1-3 are the usual ZPC, and steps 4 & 5 are for the Downhill Assist / Crawl Control (if equipped).

Could it really be that simple? Could Lexus have just not done step 4? I mean the code C120A is actually even referenced in Step 4. It literately says to do this step if you get that code.

So I said fck it. . .I get two paper clips, drive to a flat, long street, and go through steps 1-3 (which I had done before), that took maybe 2 minutes. Then I go to step four. I connect the two paper clips, flip my Downhill Assist knob up and down once, and BAM!!! light is gone. 15 extra seconds. That was it!

I could understand how a small indy shop could miss this, but for Lexus to miss it, to charge me $220 and then ask for $700 more was ludicrous. Of course I talked to the service guy who claimed that "all the work the tech did must have solved the problem and your reset was just coincidence" but he still refunded my money in full.

So what is the lesson here? Listen to fellow members, get codes, do your own research, and question absolutely everything the dealer tells you.
 
Unsure if the 460 and 470 are identical regarding this issue. There are no active codes when connecting to techstream. I have no lights on the dash when starting and driving the car. The vsc issues happens randomly when cornering and if I let the car roll backwards on an incline. I’ve done the ZPC calibration via techstream as well as the wire method. Same results. I start the car, pull live data and the steering angle is at 1150, until I drive the car. It specifically states in the print out from Toyota for the ZPC sequence that steering angle will read 1150 until driving, and the new data is learned and stored. Mine never reads anything other 1150 upon startup, hence why I’m wondering why the ZPC calibration won’t take. Never had a single issue before this new rack was installed. Both dealerships said that if there was some damage to wiring etc due to install of the new rack it would cause a code to pop up somewhere. Kicking myself for replacing a leaking rack, should’ve just let it be and lived with it, as the vehicle still drove just fine and had no issues.
 
The steering angle only update after you drive straight above a certain speed.

If the steering angle is bad, it would store fault code.

The roll backward is normal. It's part of anti roll back feature.

It's is possible that the steering was off center when the rack was connected back. Is the left and right full rotation the same? What about tie rod adjustment? Relatively centered both side or off to one side quite a bit?
 
Steering rack is centered. The tech at Lexus drove the car, turned the wheel all the way to the left, back to center, then to the right. Same amount both ways. I have had the car aligned twice, both within factory spec…. There are no active dtc, but I can pull the stored codes and they all relate to yaw rate, wheel speed sensor faults, etc. I was told they don’t have any input as they aren’t showing as current dtc. I tried reset them via techstream in the abs/vsc tab. When I pull the stored codes again, the same ones come up?
 
There are no active dtc, but I can pull the stored codes and they all relate to yaw rate, wheel speed sensor faults, etc. I was told they don’t have any input as they aren’t showing as current dtc. I tried reset them via techstream in the abs/vsc tab. When I pull the stored codes again, the same ones come up?
Need those codes.
If it's intermittent it means the problem happens intermittently.

If samewheel speed sensor comes up all the time it most likely bad wheel bearing. It might be just the magnet parts falls off and no wheel play yet.

Yaw sensor is right on top of transmission Tunnel but very seldom get damaged.

Steering angle sensor can develop blank spot due to wear. If the VSC trigger at same corner every time it might be this. The code would be temporary and reset after restart but VSC would become a lot more sensitive after this trigger.

To 100% diagnose this is to use data logging feature of techstream and try to duplicate the event that trigger the faults.
 
When I do the signal check this is what I’m getting

IMG_4993.jpeg


IMG_4992.jpeg


IMG_4991.jpeg
 
With that many errors, it's not zero point problem. You might have water intrusion problem and cause the VSC wiring to get intermittent signal.

I think all of that goes to driver side kick panel. It's a very big multi connector junction box.
 
I highly doubt it’s due to water intrusion, I never had a single issue with the vehicle until the new steering was installed 2 months ago. I can get the vsc to kick on during driving on specific roads and off ramps, every time. It’s when the car has some body roll and is turning. Hence a yaw rate issue
 
Anyone able to confirm if you pretty much immediately need to do the 25mph+ straight line drive after the ZPC reset, or do I have some wiggle room to get out of the neighborhood onto a main road (like 3 90 degree right turns and some gentle curves)?
 
After having the vehicle at both a Lexus and Toyota dealership, and both stating the vehicle had no issues, I ultimately replaced the steering rack again. I guess I got a bad unit from rock auto. With the new one, no more issues. Haven’t checked to see if the stored codes have cleared or not
 
Anyone able to confirm if you pretty much immediately need to do the 25mph+ straight line drive after the ZPC reset, or do I have some wiggle room to get out of the neighborhood onto a main road (like 3 90 degree right turns and some gentle curves)?
Yes, you need immediately to do 25+ straight line. I did it yesterday and my wife watched data list and angle changed to 0. Before that i reset and drove through neighborhood and it didn’t change.
 
I'm having an issue with My GX 470 that pretty closely pertains to this thread. In techstream, there seems to be a disparity between the steering angle reading listed in the KDSS data list compared with the ABS/VSC data list. With the steering wheel centered the reading in the ABS/VSC data list is near zero, as it should be. But in the KDSS, or the suspension control ECU data lists, the reading is about -115 degrees. Though the reading in the ABS/VSC list is labeled as "steering angle sensor" and the reading in the other 2 data lists are labeled as simply "steering angle". Not sure if that's a meaningful difference. Has anyone else noticed this? Does anyone know whether the GX has more than 1 steering angle sensor? Thanks much
 

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