(Fairly urgent) LX470 AHC (frt riding bumpstop) no AHC dash light or service lights

Joined
Oct 23, 2022
Messages
38
Location
Oklahoma
I have searched all over the place and been unable to find the answer or similar issue to my problem

2005 lx470

Purchased as is and is a one owner, well maintained. PO said that it just happened one day


Rear is normal height, front is riding bump stops, fully lowered suspension

A few oddities

1) the AHC controller by shifter with buttons on it for ride height and the AHC off button, the only button that illuminates is the ride height UP and Down, the others do not have any illumination to them (picture attached) the circled are the ones that do not illuminate with even the headlights on.




2) the dash does not display any information for the AHC or the height of the vehicle, has no illumination at all

3) I can press all the different suspension functions and cannot hear anything from pump or get a flashing light or anything, not even the “off” button

4) no warning lights or service lights regarding the AHC


Additional information

The speedo and the gas gauge are not working? I doubt it could be connected but wanting to be thorough

Could the control switch have gone bad and caused this to happen?


Where do I start to do a thorough troubleshoot ?


From what I gather, you can manually make the pump run to raise the suspension, if I read that correctly, does anyone have the specific instructions for this?


Thanks for the help

C37D1557-E727-4337-B330-21047D01BE10.jpeg
 
Joined
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Location
Charleston, sc
I think many of us ripped out AHC and never looked back. I know that's not very helpful, but fewer of 100 series owners are interested in maintaining it. that may explain the lack of responses
 

jLB

Another one followed me home. Can we keep it?
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Messages
3,457
My first question would be “Does the vehicle actually still have AHC installed, or did someone do a half-assed Strutmasters ‘conversion’?”

An example of what some of the Strutmasters components look like:

 
Last edited:
Joined
Aug 3, 2022
Messages
95
Location
PA
Lots of AHC info in this thread.


You also have missing information on your dash so I would start checking fuses.
 
Joined
Nov 24, 2017
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md
Definitely follow the links above. Nothing just happens out of the blue one day;). First, press the ahc off button and make sure it’s in the on position. If the button is working, you will watch the instrument cluster say off below the picture of the AHC vehicle control. Next, only worry about the arrows. With the doors and hatch closed and engine running press the up arrow. You may or may not press on the brake and release. It should activate in park. In the instrument cluster you should see a light flashing on the raised portion of the ahc picture in the cluster, it will blink until it is moved into position. You can roll down a window and lean in To press the button (cause no other actions should be needed) and then watch from the outside.

Do this and report back. You can also try this with the down arrow.
Take a picture under your hood in front of the passenger area. That thing on the firewall is the ahc pump.
Take a pic of your shocks
Post these and we can see what’s installed.

Usually this type of issue can be due to a leaky circuit (any front ahc lines or shocks covered in fluid? Is the reservoir of the ahc pump dry?

Next I would look at the front height sensors.

In order to diagnose digitally, get tech stream which is not expensive if you follow the links here.

Ahc is an amazing system when running and maintained. My system has just been refreshed at 250k. (For the cost of fluid and globes) It rides so nice you’ll be chasing all the bushings to replace on the rest of the vehicle.
Conceptually it’s an easy system once you understand all of the parts.

Lastly, if your truck is rusty and line replacement is needed, that is the only reason to change, depending on lift needs.
 
Last edited:
Joined
Oct 23, 2022
Messages
38
Location
Oklahoma
My first question would be “Does the vehicle actually still have AHC installed, or did someone do a half-assed Strutmasters ‘conversion’?”

An example of what some of the Strutmasters components look like:

Still has the AHS
 
Joined
Oct 23, 2022
Messages
38
Location
Oklahoma
O
Definitely follow the links above. Nothing just happens out of the blue one day;). First, press the ahc off button and make sure it’s in the on position. If the button is working, you will watch the instrument cluster say off below the picture of the AHC vehicle control. Next, only worry about the arrows. With the doors and hatch closed and engine running press the up arrow. You may or may not press on the brake and release. It should activate in park. In the instrument cluster you should see a light flashing on the raised portion of the ahc picture in the cluster, it will blink until it is moved into position. You can roll down a window and lean in To press the button (cause no other actions should be needed) and then watch from the outside.

Do this and report back. You can also try this with the down arrow.
Take a picture under your hood in front of the passenger area. That thing on the firewall is the ahc pump.
Take a pic of your shocks
Post these and we can see what’s installed.

Usually this type of issue can be due to a leaky circuit (any front ahc lines or shocks covered in fluid? Is the reservoir of the ahc pump dry?

Next I would look at the front height sensors.

In order to diagnose digitally, get tech stream which is not expensive if you follow the links here.

Ahc is an amazing system when running and maintained. My system has just been refreshed at 250k. (For the cost of fluid and globes) It rides so nice you’ll be chasing all the bushings to replace on the rest of the vehicle.
Conceptually it’s an easy system once you understand all of the parts.

Lastly, if your truck is rusty and line replacement is needed, that is the only reason to change, depending on lift needs.
Thanks for the post, I have performed the tasks

The AHC off button doesn’t do anything. And nothing shows on the dash when trying

Same thing when pushing up and or down button, nothing at all on dash. Even tried the brakes


Usually this type of issue can be due to a leaky circuit (any front ahc lines or shocks covered in fluid? Is the reservoir of the ahc pump dry?

Shocks are not covered but there is a little bit of wetness on bottom of skid plates.

I’ll try to find AHC lines


Pics attached


I think the underneath side is pretty exceptional personally, very very clean

A63DDCA1-852E-40FD-B9DD-BFEAA1F7707B.jpeg


D21F7D84-E005-4EC6-8D2B-C8372BD27594.jpeg


B8E1A4EC-95FD-4337-AE49-E6624126E548.jpeg


E2E39F23-FD19-4CF1-A947-2702C773A090.jpeg


8C3B1239-B3A6-47D7-8700-43C937675616.jpeg
 
Joined
Oct 23, 2022
Messages
38
Location
Oklahoma
Lots of AHC info in this thread.


You also have missing information on your dash so I would start checking fuses.
I think I checked all of the AHC fuses? Could it be a dash fuse or something maybe? I’ll check
 

Somebodyelse5

Enginerdin'
Joined
Feb 9, 2014
Messages
3,763
Location
Tukee Town, AZ
I think many of us ripped out AHC and never looked back. I know that's not very helpful, but fewer of 100 series owners are interested in maintaining it. that may explain the lack of responses

I have first hand seen AHC ruin enough trips that it ain't worth the hassle... rip it out and never look back!
 
Joined
Oct 23, 2022
Messages
38
Location
Oklahoma
Definitely follow the links above. Nothing just happens out of the blue one day;). First, press the ahc off button and make sure it’s in the on position. If the button is working, you will watch the instrument cluster say off below the picture of the AHC vehicle control. Next, only worry about the arrows. With the doors and hatch closed and engine running press the up arrow. You may or may not press on the brake and release. It should activate in park. In the instrument cluster you should see a light flashing on the raised portion of the ahc picture in the cluster, it will blink until it is moved into position. You can roll down a window and lean in To press the button (cause no other actions should be needed) and then watch from the outside.

Do this and report back. You can also try this with the down arrow.
Take a picture under your hood in front of the passenger area. That thing on the firewall is the ahc pump.
Take a pic of your shocks
Post these and we can see what’s installed.

Usually this type of issue can be due to a leaky circuit (any front ahc lines or shocks covered in fluid? Is the reservoir of the ahc pump dry?

Next I would look at the front height sensors.

In order to diagnose digitally, get tech stream which is not expensive if you follow the links here.

Ahc is an amazing system when running and maintained. My system has just been refreshed at 250k. (For the cost of fluid and globes) It rides so nice you’ll be chasing all the bushings to replace on the rest of the vehicle.
Conceptually it’s an easy system once you understand all of the parts.

Lastly, if your truck is rusty and line replacement is needed, that is the only reason to change, depending on lift needs.
So the hydraulic hose that connects to the top of the shocks both seem to be good and not leaking

I thought the front passenger one was possibly leaking slightly at the connection but I believe it’s just from the power steering dripping (minuscule amount) down onto it


I picked up the techstream connector and cd to download it but have not been able to get it figured out, the download process just isn’t working for some reason
 

94SRUNNER

GOLD Star
Joined
Oct 9, 2006
Messages
4,270
Location
Dayton, OH
I picked up the techstream connector and cd to download it but have not been able to get it figured out, the download process just isn’t working for some reason

Did you look at the Techstream in 5 minutes thread linked above? That is a great resource.
 

suprarx7nut

YotaMD | ADGU
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Messages
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Location
Colorado
Website
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I have searched all over the place and been unable to find the answer or similar issue to my problem

2005 lx470

Purchased as is and is a one owner, well maintained. PO said that it just happened one day


Rear is normal height, front is riding bump stops, fully lowered suspension

A few oddities

1) the AHC controller by shifter with buttons on it for ride height and the AHC off button, the only button that illuminates is the ride height UP and Down, the others do not have any illumination to them (picture attached) the circled are the ones that do not illuminate with even the headlights on.




2) the dash does not display any information for the AHC or the height of the vehicle, has no illumination at all

3) I can press all the different suspension functions and cannot hear anything from pump or get a flashing light or anything, not even the “off” button

4) no warning lights or service lights regarding the AHC


Additional information

The speedo and the gas gauge are not working? I doubt it could be connected but wanting to be thorough

Could the control switch have gone bad and caused this to happen?


Where do I start to do a thorough troubleshoot ?


From what I gather, you can manually make the pump run to raise the suspension, if I read that correctly, does anyone have the specific instructions for this?


Thanks for the help

View attachment 3148752

If you have other electrical issues, I think it's somewhat likely those issues are affecting AHC as well.

Start will getting Techstream up and running. It's the only way to properly maintain and diagnose AHC.

Yup. Get Techstream running and you can learn much more, much faster. AHC troubleshooting without Techstream is an exercise in frustration.

There's a pretty lengthy series of checks and diagnostics you can run without Techstream, but you need the manual for your year vehicle and you're probably going to get the manual process wrong more than 50% of the time. It's a complicated (but reliable when maintained) system and a computer gives you all the power you need in this situation.


Since your car appears rust-free: Don't pay too much attention to the haters, AHC rocks. :) It's complex, but requires only basic maintenance. Skip the maintenance for decades and it'll eventually reach a failure point which can be very inconvenient. Thankfully the maintenance is easy, well documented (as of 2022) and relatively cheap.

Start with Techstream and report back with your data. I bet you have electrical issues beyond AHC that are making manual troubleshooting basically worthless. The data from Techstream will reveal an awful lot.
 
Joined
Oct 23, 2022
Messages
38
Location
Oklahoma
If you have other electrical issues, I think it's somewhat likely those issues are affecting AHC as well.



Yup. Get Techstream running and you can learn much more, much faster. AHC troubleshooting without Techstream is an exercise in frustration.

There's a pretty lengthy series of checks and diagnostics you can run without Techstream, but you need the manual for your year vehicle and you're probably going to get the manual process wrong more than 50% of the time. It's a complicated (but reliable when maintained) system and a computer gives you all the power you need in this situation.


Since your car appears rust-free: Don't pay too much attention to the haters, AHC rocks. :) It's complex, but requires only basic maintenance. Skip the maintenance for decades and it'll eventually reach a failure point which can be very inconvenient. Thankfully the maintenance is easy, well documented (as of 2022) and relatively cheap.

Start with Techstream and report back with your data. I bet you have electrical issues beyond AHC that are making manual troubleshooting basically worthless. The data from Techstream will reveal an awful lot.

I’ll do that, thank you!
 
Joined
Oct 23, 2022
Messages
38
Location
Oklahoma
You can put a couple of turns into your t-bars and it will probably raise the front end the right level. At least then you can drive it until you figure out techstream etc. AHC is the best. It's prbably something simple.
So it won’t hurt anything to crank the TBar up?
 
Joined
Oct 23, 2022
Messages
38
Location
Oklahoma
Okay, I FINALLY got Techstream up and working

Connects to car but I don’t see AHC as an option? Pic attached of what I’m talking about

(Plugged into OBD port located on the drivers side under dash

F17D0A6F-3CD5-4DCB-9171-CAC1EE44A856.jpeg
 

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