AHC troubles (1 Viewer)

[PADDO]

One more question that confuses me: If only dtc 32 is shown, which indicates that the front leveling valve is affected, why doesn't the height control of the rear axle work?

Height control and leveling often involves both front and rear leveling valves and the height accumulator solenoid working in unison. If one or more elements of the system aren't functioning then the ECU will default to a fail safe self protection mode and prohibit leveling and height adjustments. If it can (enough pressure in the height accumulator) it will return to N or drop to L. Pretty normal design characteristic for a servo system capable of autonomous movement to lock itself out if it detects a fault.

 

[cILx]

Ok, I will try to accept that explanation for now.

 

[cILx]

Short version:
Fixed broken wire. All seems to work

Long version:
I bought 5 meters cable with 7 wires inside that is used for wiring lights on trailers and a cable protection hose similar to what Mr T puts on the trucks he produces.
I then checked all of the wires for the control valve assembly connector with the corresponding connector in the aft left corner.
All of the wires for the control valve assembly is in the same connector, its just one wire for the accumulator solenoid that is in the other connector.
What I found out was one wire that didn't have any connection between the control valve assembly and the corner connector. Which also correlated with the fault code 32.
Doing this alone on a truck in low mode is very time consuming but it is doable. I invented many new ugly words doing this.
I did lift the truck somewhat, but the hydraulic jack my father owns is not working properly, so I could only lift it 2 inches.
Laying on the floor underneath the truck, I hit my head repeatedly on the torsion bar bracket and will probably suffer permanent brain damage from this.

I then routed the 7 lead cable with the cable protector on all the way from rear to the control valve assembly.
After that I cut the wires that I wanted in my new cable from the connectors in the rear leaving about 6 inches of pigtail.
Using wire crimping connectors with heat shrink tube I connected them to the new cable.

At the control valve assembly I cut the cable leading down to the control valve assembly and I did the same with cable for the accumulator.
Then I matched the colors from the connection job I did first and also extended the cable for the accumulator solenoid for connecting it to the newly routed cable. The same type of wire connectors as earlier was used and then I strapped up the cables and taped all connectors to a nice package.

I then started the truck and saw that the OFF lamp wasn't blinking. It had a steady glow. My immediate feeling was: success!.
It didn't last very long, since nothing happen when I pushed the up button. Now, remember, my trucks under body is covered in chewing-gum with tar-taste and so was I and I didn't want the tar-gum on the leather seats, so I was standing outside with the drivers door open.
I closed the door and still nothing happen. Not until I closed the tail gate, the truck finally came to its fully glory, rising like Atlantis from the sea!

Time consumed was probably 4 hours. 2 persons could probably do this in half the time. A garage with a proper lift and some experience, maybe 1 hour.

Yes, I could have routed just one wire, but whats the fun in that?


I would again like to thank PADDO for help and guidance with the problem I had.
Without your help, I would probably be lost, broke and still not have a working AHC-system.

 

[PADDO]

Gotta love a happy ending 7 core trailer cable is a great solution. I was going to suggest garden sprinkler system cable too, but that may not be a common item in your region.
Glad you nailed it.
Stephen

 

[Barns]

Hello guys,

I am from Czech Republic, and it seems like nobody here knows the AHC. I have visited 3 shops, two of them official toyota .. with no luck. Time and my life energy consuming procedure with my LC this autumn.

my car:
2000 LC 100 4.2, 4 speed auto, AHC still on it

findings:
*everybody was able to see 7 errors on AHC ECU, but nobody was able to read them, so I do not know exact codes
*ride is stiff, not too much, but you noticebly knows, something isnt like it should be
*last mechanic did setup of hights sensors, car did autolevel itself according to made changes on hight sensors, it is in N level
*OFF is blinking
*car wont go to L or H levels, no response to sport comfort switch
*there is no oil leake, everything is dry


as my findings are wery simmilar to what Cilx described, I thing problem might be in wiring.

I am more into IT than car industry, but what else I could do after 3 month than do it by myself I have friend of mine, which is electrician, he is going to check/repair wiring, but he needs to get that wiring out of the car. I am looking for some schema where are all these connectors plugged on the car? some picture may save me also some hints how to unplug them gently?

I found one on each silenoid
control valve assembly is another
than something has to go to ecu?

 

[suprarx7nut]

Hello guys,

I am from Czech Republic, and it seems like nobody here knows the AHC. I have visited 3 shops, two of them official toyota .. with no luck. Time and my life energy consuming procedure with my LC this autumn.

my car:
2000 LC 100 4.2, 4 speed auto, AHC still on it

findings:
*everybody was able to see 7 errors on AHC ECU, but nobody was able to read them, so I do not know exact codes
*ride is stiff, not too much, but you noticebly knows, something isnt like it should be
*last mechanic did setup of hights sensors, car did autolevel itself according to made changes on hight sensors, it is in N level
*OFF is blinking
*car wont go to L or H levels, no response to sport comfort switch
*there is no oil leake, everything is dry


as my findings are wery simmilar to what Cilx described, I thing problem might be in wiring.

I am more into IT than car industry, but what else I could do after 3 month than do it by myself I have friend of mine, which is electrician, he is going to check/repair wiring, but he needs to get that wiring out of the car. I am looking for some schema where are all these connectors plugged on the car? some picture may save me also some hints how to unplug them gently?

I found one on each silenoid
control valve assembly is another
than something has to go to ecu?

Get techstream. Fixing multiple error codes without techstream is going to be extremely time consuming and difficult.

Get Techstream and a copy of your model's Toyota repair manual/ electrical wiring diagram (from ebay) and you'll save yourself a ton of time.

 

[Barns]

I have not ordered techstream yet, two original toyota shops told me, that they were not able to read codes from AHC ECU.

Meanwhile I tried to read DLC1 codes and than reset ECU, the result of codes remains exactly the same after the reset. 13,18,31,32,33,34,36

Could anyone please translate these codes?

 

[uHu]

You really need the FSM. It's really informative and will tell you the normal signal for each pin of the ECU.
Those codes make up nearly all your sensors and the 4 valves in the valve block. Sounds like somebody unplugged an ECU plug. Did someone work on your audio system? or steering shaft? or ignition switch?