Disabling the AHC and AVS systems, no warning lights. (9 Viewers)

[lx200inAR]

AHC and AFS have separate modules. You can disconnect the AHC module via the canbus junction in the back and leave AFS plugged in.

As long as your height control sensors are plugged in AFS works as normal.

If @clouter left the AFS module and height control sensors alone then it’s easy fix. Start your truck, turn on headlights and grab two 10mm wrenches and loosen one of the front sensors and adjust it up and down and you’ll see the headlight move.

I get they are two modules, but the sensors are only connected to one. The AHC ECU processes the output of the height sensors and computes to actual height. Then I assume that data is shared across the CANBUS. I could definitely be wrong in this, but that’s how I’ve always guessed it worked. Once you unplug the AHC ECU, not sure how you’d get true height data. I guess it’s possible the AFS ECU is what shares the height data for the rear sensors. That would make some sense since vehicles without AHC still have the height component for any trucks that have auto adjusting headlights. Probably easy to determine with the wiring diagrams.

EDIT: After checking the wiring diagrams for the AFS ECU, it appears there are direct connections from the suspension ECU to the AFS ECU to provide height data outside of the CAN BUS. Also, it was probably already known by people who were doing it, but the connections being disconnected in the video are CAN bus connectors and not power connectors. So, what you are unplugging is the ability for the suspension ECU to "talk" to the rest of the ECUs over the CAN BUS. Any other functions being performed by the suspension ECU would continue to work, as long as you don't pull the fuse on the suspension ECU. This is probably where some of the confusion stems from. If you pull power from the suspension ECU, I suspect you get an AFS error due to those inputs dying on the AFS ECU.

 

[tbisaacs]

I get they are two modules, but the sensors are only connected to one. The AHC ECU processes the output of the height sensors and computes to actual height. Then I assume that data is shared across the CANBUS. I could definitely be wrong in this, but that’s how I’ve always guessed it worked. Once you unplug the AHC ECU, not sure how you’d get true height data. I guess it’s possible the AFS ECU is what shares the height data for the rear sensors. That would make some sense since vehicles without AHC still have the height component for any trucks that have auto adjusting headlights. Probably easy to determine with the wiring diagrams.

Curious what you find. My AFS still works the same

 

[teejnut]

Curious what you find. My AFS still works the same

So do you keep the height sensors installed even after removing AHC?

 

[sedole]

So do you keep the height sensors installed even after removing AHC?

Yes, have to keep the height sensors to keep AFS still working. That's what I did.

 

[lx200inAR]

Curious what you find. My AFS still works the same

Thanks for this. Looking at the FSM, it appears the height data comes from the suspension ECU via a separate path than the CAN BUS. There are 4 wires directly between the suspension and AFS ECUs. So as long as you leave the sensors in place and don't remove power from the suspension ECU, it would make sense that AFS continues to work, as you've experienced. I suspect this is a fail-safe designed in by Toyota so that even if you had a CAN BUS failure, the headlight control would continue to work. There is a whole section of the FSM that explains what features would still work if communication to certain systems was lost.

I edited my previous posts to not leave erroneous "info" hanging out.

 

[clouter]

Thanks guys !
I'll try this as soon as I take the truck outta storage in spring and report back

 

[Omsok]

So do you keep the height sensors installed even after removing AHC?

AFs worked for me.

Didn't disco height sensors.

 

[tbisaacs]

I pulled the driver side slider today to decommission some accumulators….

For those of you who’ve done this, curious how much progress you’ve made. I’ve found the front most cylindrical accumulator to be super hard because the top bolts are overlapped by body.

 

[turbo8]

I pulled the driver side slider today to decommission some accumulators….


View attachment 3862111

For those of you who’ve done this, curious how much progress you’ve made. I’ve found the front most cylindrical accumulator to be super hard because the top bolts are overlapped by body.

I was able to remove everything. The real pain was removing all the hard lines. I ended up cutting some of the hard lines in multiple places to get them out.

 

[lx200inAR]

I pulled the driver side slider today to decommission some accumulators….


View attachment 3862111

For those of you who’ve done this, curious how much progress you’ve made. I’ve found the front most cylindrical accumulator to be super hard because the top bolts are overlapped by body.

Sounds like you need a body lift!

 

[tbisaacs]

I was able to remove everything. The real pain was removing all the hard lines. I ended up cutting some of the hard lines in multiple places to get them out.

I’ll try harder

 

[propernorf]

I also removed them all. As @turbo8 said, I had to cut a few lines and was left with the one above the tank for a few months until my fuel pump failed the other day. I had to drop the tank and removed the last one.

 

[sedole]

Was also able to remove all of mine, and also had to cut a few hard lines. It’s a big pita though.

 

[tbisaacs]

For those of you deleting your AHC and selecting shocks:

Rear shocks with piggy-back reservoirs will likely rub on the swaybar. This problem is unique to 570s because Land Cruiser's have KDSS and the sway bar mount is behind the axle. I went with Dobinson MRAs for my AHC delete and was seeing minor contact and full droop and despite being able to adjust and clock the reservoirs, I couldn't get into a position that would 100% clear.

So I worked with a local fabricator to make some tabs to move the reservoirs outboard. These clear at full articulation and are way easier to adjust since i dont need to crawl under the rig.

Finished product

 

[borysj5]

Sorry for my English
LC200 2008
I want to replace AHC for a permanent suspension, I read the whole thread but I have a few questions:
Can you tell me which fuses in the passenger fuse box?
Which relay did you take out in the engine compartment?
Is AHC ECU on the left side of the trunk?
Maybe some phot where is it?

 

[turbo8]

Sorry for my English
LC200 2008
I want to replace AHC for a permanent suspension, I read the whole thread but I have a few questions:
Can you tell me which fuses in the passenger fuse box?
Which relay did you take out in the engine compartment?
Is AHC ECU on the left side of the trunk?
Maybe some phot where is it?

This video shows where the ACH ECU is.

 

[borysj5]

Thank you very much, without this information I have no way to start. Thanks to you, it will mount the Bilstein 6112/5160 set.
I will wait for a photo where there are fuses and a relay

 

[steezy]

For those of you deleting your AHC and selecting shocks:

Rear shocks with piggy-back reservoirs will likely rub on the swaybar. This problem is unique to 570s because Land Cruiser's have KDSS and the sway bar mount is behind the axle. I went with Dobinson MRAs for my AHC delete and was seeing minor contact and full droop and despite being able to adjust and clock the reservoirs, I couldn't get into a position that would 100% clear.

So I worked with a local fabricator to make some tabs to move the reservoirs outboard. These clear at full articulation and are way easier to adjust since i dont need to crawl under the rig.


View attachment 3869375

View attachment 3869377

Finished product

View attachment 3869378

Damn! I thought you were a holdout?!

What’s the verdict post-surgery?

 

[tbisaacs]

Damn! I thought you were a holdout?!

What’s the verdict post-surgery?

It’s okay to change your mind

After seeing how crusty all of the lines and components are as in removing them, I feel good about my decision.

Ride is dialed in now. IMO high end aftermarket stuff wins on dampening and rebound control. AHC wins for versatility.

 

[lx200inAR]

Thank you very much, without this information I have no way to start. Thanks to you, it will mount the Bilstein 6112/5160 set.
I will wait for a photo where there are fuses and a relay

The fuses and relays are in the main panel under the hood. They should be labeled. You don't really want/need to do any more than pulling the can bus connector to the suspension ECU. Otherwise, you will get other lights/warnings on the dashboard. I suppose pulling the fuse/relay for the AHC pump wouldnt hurt anything, but isn't really necessary.

Here is another video where the goal was specifically to turn off AHC and remove warnings from the dash. The plug he is removing is not actually directly into the suspension ECU. It's on a connector block closer to the door frame.