NeutronJon
New member
I have a 2005 Limited with RAS. Recently, I've been having problems with ride height that I have diagnosed to the right height sensor. When viewing the output values through TechStream, I have concluded that the output signal is still linear, but corrosion is causing the sensor to not read in the range that the computer is looking for. I thought about this for a while, and have come up with a possible solution. What if I made a signal conditioner that would take the value coming from the sensor, compare it to a programmed minimum and maximum, and then output the value the computer is looking for.
The basic flow path would be as follows:
Suspension ECU sends out +5V to the detector, expecting the detector to return a value that is proportional to ride height.
I would take the ECU +5V and use it to power an Arduino microcontroller. The Arduino would pass the +5V along to the sensor. The variable sensor output (the wiper of the potentiometer) would be read by the Arduino unit using an AnalogRead function. During initial installation, a value for minimum and maximum height would be stored in the Arduino memory. By comparing the current value returned by AnalogRead to the saved min and max, we could determine the current height. This would then be output back to the suspension ECU via an AnalogWrite output pin, based on the required minimum and maximum that the computer is looking for.
This would also allow the user to perform a "software lift" by changing the output signal being sent to the ECU. If you want the rear end higher, tell the ECU that it's lower than it actually is. The ECU will raise height until it senses that the height is correct. This would actually be the height that you choose.
One Arduino has enough I/O capability, as well as processing power to handle both sensors. A damping circuit or software loop may be necessary to limit the rate of change of input into the ECU in order to limit overshoot and unnecessary cycling of the compressor and solenoid valves in the RAS system. You could also perform a cross check by comparing the two sensors (which should be relatively equal in normal, on-road conditions). You could also build a fail safe into the system that would allow the user to manually set the output voltage so that ride height could be manually controlled above the speed/engine RPM limits that are hard coded into the ECU.
Has anyone else ever considered/worked on something like this before? Has anyone else ever modified the height sensors to something completely different than OEM? I'm looking for other ideas to produce a more stable system. Someone might also be able to use this concept to provide a factory auto-leveling feature to an aftermarket airbag system as well.
Jon
The basic flow path would be as follows:
Suspension ECU sends out +5V to the detector, expecting the detector to return a value that is proportional to ride height.
I would take the ECU +5V and use it to power an Arduino microcontroller. The Arduino would pass the +5V along to the sensor. The variable sensor output (the wiper of the potentiometer) would be read by the Arduino unit using an AnalogRead function. During initial installation, a value for minimum and maximum height would be stored in the Arduino memory. By comparing the current value returned by AnalogRead to the saved min and max, we could determine the current height. This would then be output back to the suspension ECU via an AnalogWrite output pin, based on the required minimum and maximum that the computer is looking for.
This would also allow the user to perform a "software lift" by changing the output signal being sent to the ECU. If you want the rear end higher, tell the ECU that it's lower than it actually is. The ECU will raise height until it senses that the height is correct. This would actually be the height that you choose.
One Arduino has enough I/O capability, as well as processing power to handle both sensors. A damping circuit or software loop may be necessary to limit the rate of change of input into the ECU in order to limit overshoot and unnecessary cycling of the compressor and solenoid valves in the RAS system. You could also perform a cross check by comparing the two sensors (which should be relatively equal in normal, on-road conditions). You could also build a fail safe into the system that would allow the user to manually set the output voltage so that ride height could be manually controlled above the speed/engine RPM limits that are hard coded into the ECU.
Has anyone else ever considered/worked on something like this before? Has anyone else ever modified the height sensors to something completely different than OEM? I'm looking for other ideas to produce a more stable system. Someone might also be able to use this concept to provide a factory auto-leveling feature to an aftermarket airbag system as well.
Jon
