Hello everyone,
I appologize that by first post post is to seek help.
Beginning of the year, I bought a Toyota LC200 V8 Diesel with 210 000 kms - with the AHC system. It failed quite quickly, with the error code C1754 (Front gate solenoid valve malfunction) and the famous message "CHECK 4-wheel AHC". I spent the last month reading, collecting documentation and getting to know more the AHC system.
After thorough investigation, following the repair manuel, I could conclude that the "No. 1 HeightControl Valve" needed replacement [P/N: 48940-60020]. Ordered one (new) from Japan, received, tried to disassemble the faulty one. Got into a pile of seized union nuts and bolts (you can see on the picture below that rust didn't spare the car. In yellow, the part faulty).
In order to work on the bench to replace the "No. 1 Height Control Valve", I decided to dismount the complete control center unit.
- Bleed out the pressure from the 5 bleeders (4 accumulators and height accumulator).
- Unscrewed the tubes coming from the pump, as well as the 4 tubes from the "Center Suspension Control Cylinder".
- removed the parts out of the car to work comfortably.
Illustration of the parts uninstalled and tubes disconnected:
It took nearly one month to receive the additional spare parts, so the fluid got completely emptied from the system and the pump reservoir.
I could clean the existing, replace the parts, remount everything on the car, refilled the pump reservoir way above the max, and hoped that everything would work straight after restarting the car !
Good news is: code C1754 is not popping out anymore!
Bad news is: car starts but after 1-3 seconds, throw the "CHECK 4-wheel AHC" error message with the code C1763 (abnormal pressure) in Techstream.
I checked a few things: pump relay, harness, tried pump with 12V directly, and it runs.
I also checked at the inlet of the "No. 1 Height Control Valve" and there is fluid arriving so I assume the pump is well primed.
I tried deleting the code with enging running - but it immediately comes back (tried like 10 times).
If ignition is on without engine running, the "CHECK 4-wheel AHC" error message doesn't pop up.
Now I get that there is air in the whole system instead of fluid. But how do I get to do refill the whole system and bleed it if I can't get it to start?
Any input hightly appreciated as I kind of struggle knowing what to do / try next.
Thanks for reading it this far!
Matthieu
I appologize that by first post post is to seek help.
Beginning of the year, I bought a Toyota LC200 V8 Diesel with 210 000 kms - with the AHC system. It failed quite quickly, with the error code C1754 (Front gate solenoid valve malfunction) and the famous message "CHECK 4-wheel AHC". I spent the last month reading, collecting documentation and getting to know more the AHC system.
After thorough investigation, following the repair manuel, I could conclude that the "No. 1 HeightControl Valve" needed replacement [P/N: 48940-60020]. Ordered one (new) from Japan, received, tried to disassemble the faulty one. Got into a pile of seized union nuts and bolts (you can see on the picture below that rust didn't spare the car. In yellow, the part faulty).
In order to work on the bench to replace the "No. 1 Height Control Valve", I decided to dismount the complete control center unit.
- Bleed out the pressure from the 5 bleeders (4 accumulators and height accumulator).
- Unscrewed the tubes coming from the pump, as well as the 4 tubes from the "Center Suspension Control Cylinder".
- removed the parts out of the car to work comfortably.
Illustration of the parts uninstalled and tubes disconnected:
It took nearly one month to receive the additional spare parts, so the fluid got completely emptied from the system and the pump reservoir.
I could clean the existing, replace the parts, remount everything on the car, refilled the pump reservoir way above the max, and hoped that everything would work straight after restarting the car !
Good news is: code C1754 is not popping out anymore!
Bad news is: car starts but after 1-3 seconds, throw the "CHECK 4-wheel AHC" error message with the code C1763 (abnormal pressure) in Techstream.
I checked a few things: pump relay, harness, tried pump with 12V directly, and it runs.
I also checked at the inlet of the "No. 1 Height Control Valve" and there is fluid arriving so I assume the pump is well primed.
I tried deleting the code with enging running - but it immediately comes back (tried like 10 times).
If ignition is on without engine running, the "CHECK 4-wheel AHC" error message doesn't pop up.
Now I get that there is air in the whole system instead of fluid. But how do I get to do refill the whole system and bleed it if I can't get it to start?
Any input hightly appreciated as I kind of struggle knowing what to do / try next.
Thanks for reading it this far!
Matthieu
