C1721 Damping force Control Actuator FR Circuit & C1723 Damping force Control Actuator RR Circuit (1 Viewer)

[LanghorneLX]

Hi!

I need some help determining where to go next. Very Bouncy ride. I replaced my rear globes and AHC fluid first (ok I see that was a mistake) but I figured it was the big wear part. I have 178Kmi and I replaced the globes at 120K. Also I could feel a dramatic thud when I back off a curb on the rear wheels. The sport to comfort selector on the AHC seems to do nothing, but I did slam on the brakes and can feel a slight difference there.

First off and likely most importantly, I have the following two trouble codes: C1721 Damping force Control Actuator FR Circuit and C1723 Damping force Control Actuator RR Circuit. I saw the thread about the exhaust leak and shorted wires. I don't have an exhaust leak as far as I can hear and I peeked at the connectors and they are not melted. This is not a through inspection, but it seemed ok at first glance.

Should I disconnect the actuators and check resistance first? Then the next step is to disconnect at the AHC ECU and check for shorts to ground or between the wires? I can see I need to adjust my level sensors and my torsion bars, but that is not my primary issue.

Also and not that important - I disconnect my AHC reservoir heater the AHC system deactivates. Its and 06 LX. I was disconnecting to get better pressures as YotoMD recommended. Should it be deactivating?

My measurements are as follows:

FL = 19-3/8"
FR = 19-15/16"
RL = 21-7/8"
RR = 22-7/16"

N position:
FR Sensor = 0.1
FL Sensor = -0.5
RR (rear?) Sensor = 0.1

Front = 4.0 Mpa
Rear = 8.3 Mpa
Accumulator = 10.6 Mpa

Thanks all!!!

 

[LanghorneLX]

Ok guys - no reply? Haha, all good.

I found a hole in the top of my muffler. I found a wad of melted plastic adjacent to the exhaust leak on top of the frame rail. I will be cutting out the muffler and splicing wires soon.

Let me know if someone needs rear globes! I have a set that were working great.

 

[SteveH]

My muffler (at 309K) is looking weary on the bottom - I will feel up on top of it for a hole or rust. Thanks for the tip! Can't help you with the AHC question.

 

[tahakamee]

Ok guys - no reply? Haha, all good.

I found a hole in the top of my muffler. I found a wad of melted plastic adjacent to the exhaust leak on top of the frame rail. I will be cutting out the muffler and splicing wires soon.

Let me know if someone needs rear globes! I have a set that were working great.

I’m not really mechanically inclined but would like to try out the solution for C1723. Can you please help me out from where I could start?

 

[LanghorneLX]

How do you know you have the code?

 

[tahakamee]

How do you know you have the code?

I’ve checked using Techstream plus ride quality’s a bit different.

 

[LanghorneLX]

Ok - well that is just one of the two codes it because you are not getting the signal from the RR damping force control module to the suspension computer.

Two things to check - make a 4.5v battery source and do the test in the FSM as described by another ih8mudder above. And if you get the ohms in spec on all the terminals then look for an open ground or melted wires by the top of your muffler on the frame rail.

 

[WanderingWarrior]

Ok - well that is just one of the two codes it because you are not getting the signal from the RR damping force control module to the suspension computer.

Two things to check - make a 4.5v battery source and do the test in the FSM as described by another ih8mudder above. And if you get the ohms in spec on all the terminals then look for an open ground or melted wires by the top of your muffler on the frame rail.

Long shot but do you still have the older globes? Just got a 1999 LX and have same codes you did with some wire issues due to previous exhaust issues with previous owner and also some globes issues. Just came across your thread. Doubt you have the globes but if you do I’d love to connect with you! Thank you!!

 

[LanghorneLX]

Long shot but do you still have the older globes? Just got a 1999 LX and have same codes you did with some wire issues due to previous exhaust issues with previous owner and also some globes issues. Just came across your thread. Doubt you have the globes but if you do I’d love to connect with you! Thank you!!

I sold them a few weeks ago. Sorry! If you buy new, remember there are 500cc and 400cc (rear and front, respectively). Be sure to check your model/year specs before you buy.

 

[WanderingWarrior]

I sold them a few weeks ago. Sorry! If you buy new, remember there are 500cc and 400cc (rear and front, respectively). Be sure to check your model/year specs before you buy.

Hi again. Curious did you ever get your C1721 and C1723 codes resolved and fixed? I also have them and today when searching for 15 seconds found the burnt and damaged wires above the exhaust area near frame rail. Will try to get my Toyota mechanic friend to further check it out Before we possibly take to a mechanic who handles electrical as we aren’t that confident in handling the splicing etc. How did you do it? Yourself? Use a shop?

And would you happen to know what the dark metal corroding pipe is under the burnt wires in my picture? I’m assuming a fuel line that corroded also because of the heat from exhaust that previous owner took a while to address. Or is it something else? Would like to fix it also when I have the wiring harness issue fixed for the damper codes.

I was able to adjust my height and pressures to within range of what ABCs of AHC all suggest in their posts and ride has gotten much better but still have the two codes and now located the burnt wires of BG1 and BG2 of what diagrams showed. I have a 1999 LX470 in pretty mint condition. Even in frame. Without rust. And though 24 year old globes still working and giving me 9 graduations I want to improve ride further by replacing them with fluid replacement at the time but none of that will make ride better if these codes for damping still there and not letting car properly go into comfort setting. Trying to address these codes and fix the wiring prior to moving on with new globes. Thank you!

 

[LanghorneLX]

Oh man, sorry to hear that you have the same problem. Ok so I did fix this myself. I got techstream and the windows xp emulator (which you probably have if you have these codes). Then I removed the rear wheel and used an angle grinder to remove a 1" x 20" strip of metal from the body to gain access to the wires. I was very careful not to hit the wires or brakelines/fuel lines. I am not sure what the line you have pictured there is, but just follow it to a device and you will know if its brake, suspension hydraulic, fuel, etc. Sorry I just don't remember. But from there I spliced with soldier. It was really hard to determine the wire colors because it was so burnt up, but I tested it several times before I put it back together. I also removed the quick connectors in front of the wheel to resplice so it made it easier. Be sure to paint and/or undercoat when you are done so it doesn't rust away. Its a very wet area and we want these cars to go 300K mi +. lol.

 

[WanderingWarrior]

Do you know what connectors these are?

Oh man, sorry to hear that you have the same problem. Ok so I did fix this myself. I got techstream and the windows xp emulator (which you probably have if you have these codes). Then I removed the rear wheel and used an angle grinder to remove a 1" x 20" strip of metal from the body to gain access to the wires. I was very careful not to hit the wires or brakelines/fuel lines. I am not sure what the line you have pictured there is, but just follow it to a device and you will know if its brake, suspension hydraulic, fuel, etc. Sorry I just don't remember. But from there I spliced with soldier. It was really hard to determine the wire colors because it was so burnt up, but I tested it several times before I put it back together. I also removed the quick connectors in front of the wheel to resplice so it made it easier. Be sure to paint and/or undercoat when you are done so it doesn't rust away. It’s a very wet area and we want these cars to go 300K mi +. lol.

Do you happen to know what these connectors are or where I can find them? It’s the whitish grey one in the attached picture. One mechanic said they may be discontinued. They just looked at it and are going to see if they can get me a proper estimate in coming days of what work it may require regarding splicing soldiering and getting to the area. I may do it myself also with a buddy who has the equipment. But it seems the connector in wheel well area is also damaged. Any help in locating the part number etc or where I can buy these connectors would be greatly appreciated.

 

[LanghorneLX]

Do you happen to know what these connectors are or where I can find them? It’s the whitish grey one in the attached picture. One mechanic said they may be discontinued. They just looked at it and are going to see if they can get me a proper estimate in coming days of what work it may require regarding splicing soldiering and getting to the area. I may do it myself also with a buddy who has the equipment. But it seems the connector in wheel well area is also damaged. Any help in locating the part number etc or where I can buy these connectors would be greatly appreciated.

You defiantly don not need to get the toyota part. Just get a waterproof connector on Amazon or go with no connector at all and heat shink. Here is a 2 conductor. You can also get 3, 4, 5, 6, etc. Amazon product ASIN B07FJPMML6

 

[WanderingWarrior]

You defiantly don not need to get the toyota part. Just get a waterproof connector on Amazon or go with no connector at all and heat shink. Here is a 2 conductor. You can also get 3, 4, 5, 6, etc. Amazon product ASIN B07FJPMML6

Ok thank you! Wasn’t sure with the number of wires going through that area. I “think” mine on my 99 LX are 8 wires plus abs wire making 9. Not sure. Assuming it is like others’ pictures on here - have no clue if need a connector with ability to have all 8/ 9 go through it (sorry I don’t understand connectors) or if the one you sent totally works? This 2 pin 16 awg wire one? When you say 3,4,5,6? Is it per wire we increase pin size? And once we get at this wiring harness, can it be pulled down to work on? Like does it have slack? Seems to be tied into frame at moment? Mine seems to be damaged at connector in wheel well but also about a foot prior, under rear passenger door. I think someone blowtorched area when fixing exhaust leak for previous owner.

Mechanic will get back to me in couple days or so - he saw the car yesterday and was thinking same thing of going through the wheel well as others have done. Will get back to me if he can get the Toyota connector or not and his estimate of cost of the job. I will send him this option as well as option to heat shrink as there is also another part of this wiring harness prior to connector that is also damaged and would need to be heat shrinked. And if he’s too all over the place with costs or ability (they stated they can totally do it prior to seeing car and do work on Lexus a lot) I’ll just move on to another “electrical expert” that work on cars. In Toronto, Canada area so a bit limited when it comes to mechanics outside of dealerships that can handle Lexus and AHC. Heck Lexus dealerships here barely know how to handle AHC! Plus we didn’t get LX here until 2003. But still someone should be capable. Otherwise I’ll move on it myself with my friend who has all the equipment to soldier and heat shrink. We both have just never performed it on a vehicle harness before.

I’ve handled mechanical on this such as adjusting torsion bars, measuring pressures etc. in my tech stream. Installed alternator and master brake cylinder take out and fix leak two weeks ago and performing oil change. For some reason not as confident in this compared to alternator haha. But ready to if we have to!

Thank you so much for your help on this! Got this from high end auction site with several issues that were supposedly fixed or parts that were changed per receipts and to my surprise nope, they weren’t! Have received money back but for 3 weeks trying to fix list of issues. But car overall is in amazing shape with very minimum rust per three different mechanics, including Lexus dealership, and what I’ve seen as we lifted it up for our work. 289k miles, hoping to at least get it to 400-500k miles, which would mean 15 plus years with the little driving I do.