High and Rough On One Side
02-12-18, 10:58 AM
#17
Pole Position
Thread Starter
Does your car have the sport package on it? 19" wheels, different suspension calibration, and the like? I'm with you on it being more than a bit odd two different sensors are doing it, and they're doing so with no change in the height sensors' input.
These have a dedicated suspension computer, which isn't horrible to access (it's above the glovebox)...and I happen to have a spare.
I bought it in case, while I was trying to fix my own, the computer was the culprit. Wasn't, but I did swap it out in the garage to see if behavior was the same. It was, though I don't know how different the calibration is. I know it definitely works, though. Let me know if you're interested...it's just taking up garage space. $100, shipped.
BTW, outstanding job in troubleshooting! That's exactly they way I'd have done it, your reactions and everything.
These have a dedicated suspension computer, which isn't horrible to access (it's above the glovebox)...and I happen to have a spare.
I bought it in case, while I was trying to fix my own, the computer was the culprit. Wasn't, but I did swap it out in the garage to see if behavior was the same. It was, though I don't know how different the calibration is. I know it definitely works, though. Let me know if you're interested...it's just taking up garage space. $100, shipped.
BTW, outstanding job in troubleshooting! That's exactly they way I'd have done it, your reactions and everything.
02-12-18, 11:24 AM
#18
Lexus Test Driver
That's the self-levelers making sure they don't get outta whack.
I noticed for the first time, last night, if I step on the accelerator just a little harder than what's usual for me (most of the time), I can see the headlights drop down. The reverse is true, step on the brakes, and they rise just a little.
I noticed for the first time, last night, if I step on the accelerator just a little harder than what's usual for me (most of the time), I can see the headlights drop down. The reverse is true, step on the brakes, and they rise just a little.
02-12-18, 11:32 AM
#19
Pole Position
Thread Starter
That's the self-levelers making sure they don't get outta whack.
I noticed for the first time, last night, if I step on the accelerator just a little harder than what's usual for me (most of the time), I can see the headlights drop down. The reverse is true, step on the brakes, and they rise just a little.
I noticed for the first time, last night, if I step on the accelerator just a little harder than what's usual for me (most of the time), I can see the headlights drop down. The reverse is true, step on the brakes, and they rise just a little.
02-20-18, 05:41 PM
#20
Pole Position
Thread Starter
It’s all fixed!
Ok, I’ll try to keep this somewhat short. Because of the erratic behavior and height readings on Techstream, I was sure it was going to be the air suspension ECU. I didn’t want to just try part swapping before I did some diagnosis. I had a replacement ECU lined up if it ended up being that (Thank you McKellyb!). The repair program/manual instructed me to start with the solenoids that open and close based on the height sensors reading. In order to check these, you need to remove both inner fender wells, both engine covers, the front grill, the front bumper cover, etc. Checking those first just didn’t make sense.
I checked the FL ride height sensor previously and it checked out fine using batteries, some wire and a meter but my gut kept telling me to check it again before ripping things apart because removing the FL ride height sensor takes just minutes to remove. I went ahead and removed it again and using 3 - D size batteries taped together, some wires and my meter I checked it again. Low and behold it was definitely bad now! I’ll try to upload my short video. It’s supposed to read from .45 volts on the low level and 4.1 at the max height level. Mine read about .42 on the lowest level but as I moved the sensor towards the high level it only got to about .63 at max height! This meant the sensor just kept calling for more air because it was reading way under “normal / level” height even when the corner was maxed out in height. This would then cause the other corners to start raising up to get to that level until they all maxed out or the safety kicked on the compressor to stop it from burning up. At max High the car rode so stiff it was worse then any heavy duty pickup I’ve ever driven!
The only code that came up was C1761 for “continuous power to compressor”. There was no code for the FL ride height sensor because technically it was working because it was reading heights but the heights were just WAY OFF! Anyway, $160 for the part (Aisin) from Rock Auto instead of $400 from the dealer and then about 20 minutes to change it and all is well. Hooked up Techstream and all the levels are reading very close to each other and each corner is within 1/4”.
I checked the FL ride height sensor previously and it checked out fine using batteries, some wire and a meter but my gut kept telling me to check it again before ripping things apart because removing the FL ride height sensor takes just minutes to remove. I went ahead and removed it again and using 3 - D size batteries taped together, some wires and my meter I checked it again. Low and behold it was definitely bad now! I’ll try to upload my short video. It’s supposed to read from .45 volts on the low level and 4.1 at the max height level. Mine read about .42 on the lowest level but as I moved the sensor towards the high level it only got to about .63 at max height! This meant the sensor just kept calling for more air because it was reading way under “normal / level” height even when the corner was maxed out in height. This would then cause the other corners to start raising up to get to that level until they all maxed out or the safety kicked on the compressor to stop it from burning up. At max High the car rode so stiff it was worse then any heavy duty pickup I’ve ever driven!
The only code that came up was C1761 for “continuous power to compressor”. There was no code for the FL ride height sensor because technically it was working because it was reading heights but the heights were just WAY OFF! Anyway, $160 for the part (Aisin) from Rock Auto instead of $400 from the dealer and then about 20 minutes to change it and all is well. Hooked up Techstream and all the levels are reading very close to each other and each corner is within 1/4”.
Last edited by Brewmyown; 02-20-18 at 06:41 PM. Reason: typo
02-21-18, 04:49 AM
#22
Lexus Test Driver
Nice! Well-diagnosed and well-executed repair of a quite complex system.
At what point did you think, "uh, oh, is this a bottomless rabbit hole?"
At what point did you think, "uh, oh, is this a bottomless rabbit hole?"
02-21-18, 08:29 AM
#23
Pole Position
Thread Starter
Once I really started digging into the diagnosis avenue laid out in the repair software/manual and it suggested the first step to determine the culprit of the C1761 fault was to start disassembling numerous body parts, I thought to myself that it just didn't make sense to start there. I knew from using Techstream and turning all of the switches and solenoids on and off and hearing them click, etc. that they worked. So that made me rethink my diagnosis path and check a part that I already checked because it made the most common sense as to what was happening on my car. Luckily, it was the most easily accessed part in the system and voltage testing confirmed (the second time) that it was in fact bad. It was reading voltage numbers but way off from what they should have been reading. Not throwing a code for a faulty / bad sensor threw me for a loop but sometimes common sense and determination works better than following a diagnostic page in a factory repair manual.
02-21-18, 09:41 AM
#24
I think I had that C1761 in my cars fault history when I bought it but it has not showed up again after multiple scans with Techstream. I was worried at first but I've been to the dealership multiple times to get my heat sorted out and the tech never mentioned it as being a problem.
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