C1741 & C1751 AHC suspension issues (1 Viewer)

[noobsthename]

My 2004 GX470, 150K miles recently started having some Air Suspension Issues. First it began about a month ago with what I believe to be a leak in the air spring. Eventually when starting the car about 2 weeks ago I noticed that I couldn't adjust the height setting and it was stuck in "N" (neutral), however, restarting my car usually fixed the issue. I had ordered the air springs but didn't get around replacing them until this weekend, at that point it may have been too late as the automatic height control was stuck in "N" no matter what I did.

I even tried clearing the DTC codes using the jumper wire between terminals 4 & 13 on the OBDII port and pressing the brake 8 times in <5 sec method. I would get the system check message to pop up on the nav screen, and the beep, but that didn't fix the issue. I decided to give in and took it to the dealership, they told me that they read codes C1741 & c1751, but wanted another $400 to further diagnose the issue.
The detecting condition for code C1751 is "With the AIR SUS relay activated, the vehicle does not go up to the standard vehicle height after the 100 sec. elapsed."

So I'm guessing that the leak got so bad it was taking longer than 100s to pump up the the airbag causing the C1751 code. In the repair manual it says "In this case, however, the vehicle height operation is resumed approx. 10 min. after the ignition switch is turned ON after the ECU detects the first error. If ECU detects another error, it takes 70 minutes until the control is resumed."

I've definitely driven 10 minutes since the failure occurred but not 70 minutes. My question is do I have to actually drive the car 70 minutes for that code to clear, or can I just leave it idling in the driveway? Can I just clear the code using an OBDII scanner from amazon? Thank you.

 

[blacktec]

Wow 150k before any issue? Good going! If you want to keep the air suspension, you may have to replace the compressor at this point as well.

 

[runningdrew]

I had some issues just like yours. Stuck in N. Air springs leaking etc. Before my new air springs arrived I tricked the AHC to increase ride height and "seal" the leaks that I had as a temporary bandaid. But before I was able to do it the compressor stopped working, stuck in N, switch didn't work, Etc. I did the whit short process, tap brakes to go into service menu and clear it a few times.. .. . Although my screen looked different than others.. .. I disconnected the battery for 20 minutes, did the short--circuit thing like 5 times, and it eventually started working.

Replaced springs last week with Amazon cheapies, riding fine since.

 

[noobsthename]

I figured it out, and writing here in case anyone runs into the same issue I did where they replaced the bag but the system was still stuck in N. I kept my car idling for 70 minutes in order to try and clear the code but that didn't work, so you might have to actually drive it around for 70 minutes, but even 5 minutes of driving with the bag bottomed out was killing my back so screw that noise.

Like I said in my initial post the Automatic Height Control (AHC) system has a fail-safe in it so you don't burn out the compressor. In my case before I replaced the leaky bag and the car was turned on, the compressor stayed on for more than 100 seconds (to keep up with the leaky bag) this triggered the C1751 Code and locked out the system for 10 minutes then another error was detected and locked out for 70 minutes. Per the repair manual:

"Thus DTC C1751/51 may be output and vehicle height control may be suspended (This is not abnormal).
In this case, however, the vehicle height operation is resumed approx. 10 min after the ignition switch is
turned ON after the ECU detects the first error. If ECU detects another error, it takes 70 minutes until the
control is resumed."

Here is what you need to solve the issue in 3 minutes:
1. Bluetooth OBD II reader
2. OBD Fusion APP

Directions:
1. Plug OBD II Reader into car
2. Launch OBD Fusion and Connect, set up the vehicle setting (Model, year, etc.)
3. Go to Settings>Purchase Extras>Toyota, Lexus, Scion
4. Purchase and Download the corresponding year Enhanced Diagnostics for $9.99
5. Disconnect your bluetooth/OBD Fusion
6. Reconnect and choose the Air Suspension Module
7. Read and Clear codes.
8. Problem Solved.

Again, this will only work if you've already fixed the leak, otherwise you'll clear the codes then they'll come right back when the compressor stays on for more than 100s. I used the Arnott bags off of Rockauto and so far they've been great.

Hope this helps someone so they don't waste as much time as I did trying to figure this out!