RTH Needed: AHC "OFF" blinking; possible noise from rear shock

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dwh13

dwh13

Joined
Nov 26, 2017
Threads
35
Messages
465
Location
Charleston, SC
Evening all, I'm in Kingston, Rhode Island halfway through a 3,000 mile road trip and am having AHC woes. Here are my symptoms:

  • Today, I put the truck in High mode. It went part of the way up, then reverted to Neutral.
  • Several hours later and after the truck sat for about 2 of those hours, I started it up and the OFF light was flashing, but the ride height was normal.
  • Used Carsoft TYT reader and pulled code C1751 - continuous current to compressor motor. Cleared the code, drove around the block and it did not come back on. Ride is still in Neutral. Rear height sensor is physically intact.
  • At the same time, I noticed that there was a loud metallic clanking sound from the rear of the truck whenever I went over bumps. I don't know if this happened at the same time as the AHC OFF light; I only heard it because I had the windows down. When I grab the roof rails and rock the truck back and forth, I can reproduce the noise and it sounds to be either coming from the shock or the brake (maybe a rock between the rotor and the dust shield).
FYI, I replaced the rear springs a month ago with OEM AHC springs. I hope I didn't mess something up when I released the shocks...

Any ideas before I take it to the nearest Toyota dealer tomorrow (20 miles away)? I read the other threads on this code but all of them seemed to be riding on the bump stops - makes me think I have a different issue.
 
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Maybe check that your top bolts are still on? I could see that possibly causing an issue and the noise. Then again I have zero AHC knowledge
 
Make sure the AHC fluid level is high enough. If you put it in high mode and it runs out of fluid and is sucking air, it will flash off.
 
Check fluid level. Very good chance that there is still air with that code going off and recently replaced shocks. I got that same code for a bleed valve that was not tightened. Nearly lost all fluid but was able to add it all the fluid back in without any air entering the system. Check all bleed nipples to ensure nothing is leaking out.

With a 10mm and a bleed hose + empty bottle you can give the rears a quick short bleed at each side and see if any air escapes. Would be better with a bottle of AHC on the side if you need to bleed more out.
 
Sargy said:
Check fluid level. Very good chance that there is still air with that code going off and recently replaced shocks. I got that same code for a bleed valve that was not tightened. Nearly lost all fluid but was able to add it all the fluid back in without any air entering the system. Check all bleed nipples to ensure nothing is leaking out.

With a 10mm and a bleed hose + empty bottle you can give the rears a quick short bleed at each side and see if any air escapes. Would be better with a bottle of AHC on the side if you need to bleed more out.
Click to expand...
Oops, I replaced the rear *springs. My bad - updates the original post
 
Did you check the fluid level? I had similar issues my first time doing the fluid exchange because I didn't put enough fluid in it and the pump was cavitating. Check the fluid level in N. If you don't see any fluid in the reservoir, drop it into L. If you see fluid in the reservoir, top off as needed. If not, you'll have to bleed the system.
 
Did you check all bleed screws for any leaks? Fluid level?
Do you have your neutral pressures via techstream / obd tool?
 
Because there’s nothing worse than a thread with no solution, the issue ended up being the pump. I had no choice but to let Lexus replace it at $1,400. My car was out of commission for 5 days. The RX loaner they gave me was cramped with two people and our gear but it did the job.
 
sorry to hear that!
 
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