01 LX - C1776 code (1 Viewer)

[tyl3rd]

Hey all, been trying to track down some AHC gremlins with @2001LC

Replaced both front AHC sensors and all four globes along with a complete fluid flush about 2-3 months ago. Everything was working flawlessly for awhile, followed the AHC guide had pressures correct and cross leveled. Recently I've been having an issue where AHC won't work outside of N, 2 flashes and no movement for both HI and LO. When it would work, the front end would be higher than the rear, with a negative rake. Almost like the front end was in AHC HI and the rear was in N. I plugged up techstream and found C1776 (wheel speed sensor), a few threads around here have pointed to height sensors causing these issues. I've monitored techstream while driving and the wheel speeds reported are correct. I see a speed reading of 0 at park and when moving everything matches the speedo.

I was trying to work on it some more today adjusting height sensors and such, however, I found on the passenger side today, where the wheel speed cable and brake lines are supposed to mount to the UCA the bracket was unbolted. My best guess is that the movement of the body using AHC is causing the C1776 to trip due to the loose cable and then preventing AHC function.

1. Does anyone know if that bracket is sold separately from the entire sensor assembly?
2. Any other ideas on possible causes, i.e. is my logic sound here?

Appreciate the read and any advice.

 

[tyl3rd]

First attempt (clear code, AHC to LO -> (c1776 trigger and default back to N)

Second attempt (clear code, AHC to LO -> (c1776 trigger and default back to N)

 

[tyl3rd]

Anyone have any thoughts here? Still battling with this.

 

[trdcorolla]

A quick mud search shows the brackets available separately.

Replacement AHC sensor arm - https://forum.ih8mud.com/threads/replacement-ahc-sensor-arm.1010029/#post-11213991

Regarding your C1776, I found this using search, have you ever had a rat problem?

2004 Lexus LX470 AHC Help Needed

New poster here. I have been reading this forum for over a year which has been how long I have been trying to get my Auto Height Control issues resolved. I have done a ton of reading on troubleshooting. In a nutshell I began having issues where the front of the vehicle appeared to be in "HI"...

forum.ih8mud.com

 

[tyl3rd]

A quick mud search shows the brackets available separately.

Replacement AHC sensor arm - https://forum.ih8mud.com/threads/replacement-ahc-sensor-arm.1010029/#post-11213991

Regarding your C1776, I found this using search, have you ever had a rat problem?

2004 Lexus LX470 AHC Help Needed

New poster here. I have been reading this forum for over a year which has been how long I have been trying to get my Auto Height Control issues resolved. I have done a ton of reading on troubleshooting. In a nutshell I began having issues where the front of the vehicle appeared to be in "HI"...

forum.ih8mud.com

My sensor brackets are okay, but it looks like there’s a ton of play in the brackets that connect the wheel speed sensor wires and the abs wire. I’m just not sure why c1776 is triggering when the monitored wheel speeds are correct and accurate. Not sure about the rats lol.. only had the LX for a few months and it’s been one headache after another so wouldn’t be surprised

 

[tyl3rd]

Still grappling with this one. It seems more intermittent now. I replaced my non OEM cv's with OEM and put on new wheel bearings and hub flanges this past weekend (needed to be done outside of this issue) was hoping that maybe removing the play from the wheels with new bearings would help but it's still happening.

Wondering if something is wrong with my front sensors?

edit: also zip tied my speed sensor wire to remove most of the play in the line

 

[suprarx7nut]

Those front sensors in techstream are showing vastly different heights.

Can you very carefully measure physical heights and show new techstream values again? I suspect the sensors need to be adjusted so that the reported number in techstream matches the real world.

 

[tyl3rd]

Those front sensors in techstream are showing vastly different heights.

Can you very carefully measure physical heights and show new techstream values again? I suspect the sensors need to be adjusted so that the reported number in techstream matches the real world.

I took off both front sensors last night to double check for corrosion and they are both clean as a whistle, i'm sure they will need some adjusting after removal but here is what I have right now.

Front Left, center fender to center of grease cap: 19 & 6/16"
Front Right, center fender to center of grease cap: 19 & 5/16"

ts readings:

 

[suprarx7nut]

I took off both front sensors last night to double check for corrosion and they are both clean as a whistle, i'm sure they will need some adjusting after removal but here is what I have right now.

Front Left, center fender to center of grease cap: 19 & 6/16"
Front Right, center fender to center of grease cap: 19 & 5/16"

ts readings:
View attachment 2899137

Ok great. See lines 1 and 2 in techstream? This is a problem. The vehicle is physically level within .06 inches. The sensors are telling the ECU that the vehicle is leaning 1.2 inches to the left. Those front left and right sensors should both be reporting roughly 0.0.

You need to adjust the sensors mount on the sliding bracket until the electrical signal from the sensors matches the real world.

I'm not sure if this is causing your speed sensor problem, but it's definitely worth correcting.

 

[tyl3rd]

Ok great. See lines 1 and 2 in techstream? This is a problem. The vehicle is physically level within .06 inches. The sensors are telling the ECU that the vehicle is leaning 1.2 inches to the left. Those front left and right sensors should both be reporting roughly 0.0.

You need to adjust the sensors mount on the sliding bracket until the electrical signal from the sensors matches the real world.

I'm not sure if this is causing your speed sensor problem, but it's definitely worth correcting.

I'll take another shot at the adjustments. I've tried many times and never been able to get them within ~0.1-0.2"

Is there a specific process? I normally leave vehicle running max out wheel turn in order to access each side and then see how TS reacts. Lengthen heim joint to lower and shorten to raise values, right?

 

[suprarx7nut]

I'll take another shot at the adjustments. I've tried many times and never been able to get them within ~0.1-0.2"

Is there a specific process? I normally leave vehicle running max out wheel turn in order to access each side and then see how TS reacts. Lengthen heim joint to lower and shorten to raise values, right?

Personally, I would do it with the wheels straight and I'd only move the slotted bracket mount. I would not adjust the heim joint first.

I would adjust the low side first. Move it .25" or so and recheck techstream.

 

[tyl3rd]

Personally, I would do it with the wheels straight and I'd only move the slotted bracket mount. I would not adjust the heim joint first.

I would adjust the low side first. Move it .25" or so and recheck techstream.

Trying not to wear out my welcome, so thanks for patience here..

I just went and moved the slide around on the low side (left). It's at the bottom of the slide now, I moved it up the slide closer to the body of the vehicle and then value got further negative.. isn't the opposite supposed to happen?

 

[suprarx7nut]

Trying not to wear out my welcome, so thanks for patience here..

I just went and moved the slide around on the low side (left). It's at the bottom of the slide now, I moved it up the slide closer to the body of the vehicle and then value got further negative.. isn't the opposite supposed to happen?

No worries, happy to help.

If the slot seems to be too small to correctly set the value, you may be forced to adjust the heim joint and lengthen/shorten the rod. This is one of those things that's somewhat simple, but without looking at the assembly I won't even try to tell you which direction is right. I get it wrong more often than I get it right. Just have to make small adjustments one at a time and check TS.

 

[tyl3rd]

No worries, happy to help.

If the slot seems to be too small to correctly set the value, you may be forced to adjust the heim joint and lengthen/shorten the rod. This is one of those things that's somewhat simple, but without looking at the assembly I won't even try to tell you which direction is right. I get it wrong more often than I get it right. Just have to make small adjustments one at a time and check TS.

Ok, think I got it.. at least close enough.. However my front pressures are down to 6.2 (did L to N a few times always 6.2). Actual height is now 19 and 3/16"

 

[suprarx7nut]

Ok, think I got it.. at least close enough.. However my front pressures are down to 6.2 (did L to N a few times always 6.2). Actual height is now 19 and 3/16"

View attachment 2899265

That looks great. I'd leave it like that or maybe adjust the sensors to net you a little more height until pressure is at ~6.4 or so. Just depends on your tolerance for more messing around with it.

 

[tyl3rd]

That looks great. I'd leave it like that or maybe adjust the sensors to net you a little more height until pressure is at ~6.4 or so. Just depends on your tolerance for more messing around with it.

Thanks for the help!! Question if know the answer. Are the height sensors measuring the height individually or the height with respect to the other sensor, if that makes sense. Like if I adjust them both in the same direction equal amounts will they remain at zero?

 

[suprarx7nut]

Thanks for the help!! Question if know the answer. Are the height sensors measuring the height individually or the height with respect to the other sensor, if that makes sense. Like if I adjust them both in the same direction equal amounts will they remain at zero?

They're measuring independently, but the system will raise the vehicle until the average of the two is near (enough) to 0.

So yes. If they're at zero now and you raise them both the same, they will still report zero. That's how you do a sensor lift ( or lower).

 

[tyl3rd]

They're measuring independently, but the system will raise the vehicle until the average of the two is near (enough) to 0.

So yes. If they're at zero now and you raise them both the same, they will still report zero. That's how you do a sensor lift ( or lower).

Seems to have already come out of whack, sensor readings are not the same and changing constantly. I just bit the bullet on some AISIN sensors, will report back.

 

[suprarx7nut]

Seems to have already come out of whack, sensor readings are not the same and changing constantly. I just bit the bullet on some AISIN sensors, will report back.

Oh, perhaps I should have started with that question. Only OEM sensors count. Anything aftermarket might as well be unplugged. They really are that bad.

OEM only. Aisin should be ok as that's oem-ish.

 

[tyl3rd]

Oh, perhaps I should have started with that question. Only OEM sensors count. Anything aftermarket might as well be unplugged. They really are that bad.

OEM only. Aisin should be ok as that's oem-ish.

oh I could cancel order if needed, I assume AISIN was OEM quality. Not the case?