AHC issue - rear stuck in L (10 Viewers)

[AtinLango]

All was well, except that the rear stood a bit higher than normal in Neutral height. So i wanted to adjust it downwards a bit.

Long story short, I tried to adjust by moving the link from bottom to the middle hole in the sensor lever. Then hell broke loose. The car got stuck in L.

At one point I tried to disconnect the link and start the engine. Miraculously, the rear rose to neutral height . Then I bled the rear and the rear went to L as expected. But since then it has refused to lift up.

I would appreciate any insights on how to raise the rear back. Front is in Neutral. Thank you.

 

[RockDriver]

All was well, except that the rear stood a bit higher than normal in Neutral height. So i wanted to adjust it downwards a bit.

Long story short, I tried to adjust by moving the link from bottom to the middle hole in the sensor lever. Then hell broke loose. The car got stuck in L.

At one point I tried to disconnect the link and start the engine. Miraculously, the rear rose to neutral height . Then I bled the rear and the rear went to L as expected. But since then it has refused to lift up.

I would appreciate any insights on how to raise the rear back. Front is in Neutral. Thank you.

Have you checked the rear AHC sensors? My front dropped a few days ago while the rear remained fine - turns out front right sensor seized up from rust and simply broke in half.

 

[AtinLango]

Have you checked the rear AHC sensors? My front dropped a few days ago while the rear remained fine - turns out front right sensor seized up from rust and simply broke in half.

Yes, I checked the sensor because at one point my manual jumper diagnostic method returned error 13 (rear sensor error). After removing sensor, cleaning and putting back, the error disappeared, but the problem remained.

After that, the system was error free. But with so many attempts at resolving the issue, error 51 (continuous current to pump motor) is showing out of the blue. That is the only error at the moment.

 

[AtinLango]

After a lot of struggle with my helper mechanic, I decided to go under the car to see what was happening. It was obvious that the rear sensor lever was facing the wrong direction (facing directly down actually). My helper had put if the wrong way. I flipped it over and the car immediately rose to High.

Problem is that during several attempts, someone burnt the height control switch. So the switch u6s currently disconnected.

I cannot lower of raise the car manually. We have just tried techstream. It can lower the height, but upon driving, it gets back to High. Inspite of this, the dashboard light is stuck at N. Another thing is that techstream seems to have changed TEMS to Comfort, which is very undesirable for High mode.

I would appreciate to hear from anyone with such an experience or knowledge so that i can also figure out how to lower the car to Neutral height. It seems it is defaulting to High mode automatically.

 

[IndroCruise]

To start from the begining .....

The point is that if the AHC system and all Height Control Sensor circuits are healthy (no faults), then when the centre console switch is set at "N" height setting, the Suspension ECU will cause the the AHC Pump and the Levelling Valves to operate, allowing the vehicle to rise or fall at Front AND Rear, until the same signal of ~2.25 volts is received by the ECU from EACH of the three Height Control Sensors (Left Front, Right Front, and Rear). Based on these signals from the Height Control Sensors, the vehicle then settles at "N" height, Frint and Rear.

Similarly, when the centre console switch is set at "LO" height or "HI" height, the Suspension ECU will cause the the AHC Pump and the Levelling Valves to operate, causing vehicle will rise or fall at Front AND Rear until until the correct signal is received by the ECU from EACH of the three Height Control Sensors (Left Front, Right Front, and Rear), for "LO" or "HI" height -- whatever has been selected.

These voltages are not shown on Techstream or other scanner. Instead, the readout on Techstream for EACH of the three Height Control Sensors should be close to zero +/- 0.2 inches (or +/- 5 millimetres) at "N" height setting, as set out in the Factory Service Manual.

There is no way to set different individual voltage signals for any Height Control Sensor. The signal voltages for "LO", "N" and "HI" heights are permanently set inside the Suspension ECU. There is no way to adjust them (without re-designing the internal circuit boards within the ECU).

The 'ride height' of the vehicle at "N" height setting, measured hub-to-fender, should be about 19.75 inches or ~500mm (Front) and 20.50 inches or 520 mm (Rear) to be close to the Factory settiings for "N" height setting. These heights at are achieved by adjusting the Height Control Sensor adjusters at each Sensor.

The Suspension ECU then sets the 'ride height' for "LO" height setting and "HI" height settings.

An Owner can choose a different 'ride height' of the vehicle at "N" height setting, measured hub-to-fender, by adjusting the Height Control Sensor adjusters as desired at the Front and/or Rear (such as for so-called 'sensor lift') -- but being carerful of other changes this will cause to alignment geometry and useable suspension droop. The signall voltages received by the ECU from the Height Control Sensors do not change; they remain the same for the 'new' "N" height setting. The Suspension ECU then sets the 'ride height' for the new "LO" height setting and the new "HI" height setting..

If the combined centre console switch for AHC (Height Control) and TEMS (Comfort Control) has been damaged as described, then it is most likely that loose or damaged connections will be sending erratic voltage signals to the Suspension ECU and causing the problems described.

To overcome these problems, it would be best to acquire and fit a new switch -- see Part Number below.

Alternatively, some kind of electrical bypass might be possible with the help of an electrical person, using the attached Electrical Wiring Diagrams.

It would be essential to check that all Height Control Sensor circuits -- meaning the Sensors and the Connectors and the wiring Harnesses -- are free of any faults.

 

[AtinLango]

To start from the begining .....

The point is that if the AHC system and all Height Control Sensor circuits are healthy (no faults), then when the centre console switch is set at "N" height setting, the Suspension ECU will cause the the AHC Pump and the Levelling Valves to operate, allowing the vehicle to rise or fall at Front AND Rear, until the same signal of ~2.25 volts is received by the ECU from EACH of the three Height Control Sensors (Left Front, Right Front, and Rear). Based on these signals from the Height Control Sensors, the vehicle then settles at "N" height, Frint and Rear.

Similarly, when the centre console switch is set at "LO" height or "HI" height, the Suspension ECU will cause the the AHC Pump and the Levelling Valves to operate, causing vehicle will rise or fall at Front AND Rear until until the correct signal is received by the ECU from EACH of the three Height Control Sensors (Left Front, Right Front, and Rear), for "LO" or "HI" height -- whatever has been selected.

These voltages are not shown on Techstream or other scanner. Instead, the readout on Techstream for EACH of the three Height Control Sensors should be close to zero +/- 0.2 inches (or +/- 5 millimetres) at "N" height setting, as set out in the Factory Service Manual.

There is no way to set different individual voltage signals for any Height Control Sensor. The signal voltages for "LO", "N" and "HI" heights are permanently set inside the Suspension ECU. There is no way to adjust them (without re-designing the internal circuit boards within the ECU).

The 'ride height' of the vehicle at "N" height setting, measured hub-to-fender, should be about 19.75 inches or ~500mm (Front) and 20.50 inches or 520 mm (Rear) to be close to the Factory settiings for "N" height setting. These heights at are achieved by adjusting the Height Control Sensor adjusters at each Sensor.

The Suspension ECU then sets the 'ride height' for "LO" height setting and "HI" height settings.

An Owner can choose a different 'ride height' of the vehicle at "N" height setting, measured hub-to-fender, by adjusting the Height Control Sensor adjusters as desired at the Front and/or Rear (such as for so-called 'sensor lift') -- but being carerful of other changes this will cause to alignment geometry and useable suspension droop. The signall voltages received by the ECU from the Height Control Sensors do not change; they remain the same for the 'new' "N" height setting. The Suspension ECU then sets the 'ride height' for the new "LO" height setting and the new "HI" height setting..

If the combined centre console switch for AHC (Height Control) and TEMS (Comfort Control) has been damaged as described, then it is most likely that loose or damaged connections will be sending erratic voltage signals to the Suspension ECU and causing the problems described.

To overcome these problems, it would be best to acquire and fit a new switch -- see Part Number below.

Alternatively, some kind of electrical bypass might be possible with the help of an electrical person, using the attached Electrical Wiring Diagrams.

It would be essential to check that all Height Control Sensor circuits -- meaning the Sensors and the Connectors and the wiring Harnesses -- are free of any faults.


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Thanks, this is so elaborate.