davez26
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Extended Mode, or extra lift: possible solution
None of my tech's know of a way, so I tried to figure this out the old fashioned way, I looked through the service manuals looking for a back door. I didn't find one, but I came up with some theory of operation that might help someone. Sorry for the lengthyness.
GTR says "If the air suspension control module senses that the vehicle has grounded and lost traction, the control module can temporarily increase and/or redistribute the volume of air supplied to the affected air spring(s) to maximise the available traction. This is known as extended mode and will be indicated to the driver by the lamps on the air suspension switch flashing."
The only way I know of that the car would know it is grounded is if the car has wheel speed, but no acceleration, which I read later, "The air suspension control module uses inputs received on the CAN bus from other vehicle systems. The system uses longitudinal acceleration, lateral acceleration, steering angle and wheel speed data to control the suspension operation in differing driving conditions." Well, I don't know how to tap into a CAN bus, and modify the input signals so that the vehicle thnks it has wheel speed, but no momentum, so I went for a different tack.
We used to adjust the ride heights on the Cadillacs by adustiing the drop links. The drop link is connected to a movable point while the sensor is mounted to a solid point. The sensor gets the height signal based on how far an arm has moved from what it thinks is a base point. If we use a different length arm, we could fool the sensor into thinking the car is @ access, when it is @ normal height by using a different length link. Then, it would raise to off-road height @ when raising to normal, and still have the extra three when going into off-road. hmm. How much tinkering can the car stand? "Once set, the calibration is not required to be performed unless the air suspension control module is removed or replaced, a height sensor is removed or replaced or a suspension arm to which the sensor is connected is removed or replaced. If the removed height sensor is subsequently refitted, the calibration procedure will have to be performed to ensure the integrity of the system." sounds ominous, but can I replace just the drop link with one of a different length to fool the attached sensor? "If a replacement drop link is fitted, recalibration is not required providing the sensor body is not removed from its mounting bracket."
Theoretically, the car could be lifted by altering the length dimensions of the drop links. I'm not sure this is a good idea though. I'm not sure how much stress the CV joints can take raised and @ 65 mph. I'm not sure if the vehicle would have any uptravel left @ an extended height. I'm not sure if I could get any suspension repairs performed under warranty. In theory I think it could work.
pbrover said:
None of my tech's know of a way, so I tried to figure this out the old fashioned way, I looked through the service manuals looking for a back door. I didn't find one, but I came up with some theory of operation that might help someone. Sorry for the lengthyness.
GTR says "If the air suspension control module senses that the vehicle has grounded and lost traction, the control module can temporarily increase and/or redistribute the volume of air supplied to the affected air spring(s) to maximise the available traction. This is known as extended mode and will be indicated to the driver by the lamps on the air suspension switch flashing."
The only way I know of that the car would know it is grounded is if the car has wheel speed, but no acceleration, which I read later, "The air suspension control module uses inputs received on the CAN bus from other vehicle systems. The system uses longitudinal acceleration, lateral acceleration, steering angle and wheel speed data to control the suspension operation in differing driving conditions." Well, I don't know how to tap into a CAN bus, and modify the input signals so that the vehicle thnks it has wheel speed, but no momentum, so I went for a different tack.
We used to adjust the ride heights on the Cadillacs by adustiing the drop links. The drop link is connected to a movable point while the sensor is mounted to a solid point. The sensor gets the height signal based on how far an arm has moved from what it thinks is a base point. If we use a different length arm, we could fool the sensor into thinking the car is @ access, when it is @ normal height by using a different length link. Then, it would raise to off-road height @ when raising to normal, and still have the extra three when going into off-road. hmm. How much tinkering can the car stand? "Once set, the calibration is not required to be performed unless the air suspension control module is removed or replaced, a height sensor is removed or replaced or a suspension arm to which the sensor is connected is removed or replaced. If the removed height sensor is subsequently refitted, the calibration procedure will have to be performed to ensure the integrity of the system." sounds ominous, but can I replace just the drop link with one of a different length to fool the attached sensor? "If a replacement drop link is fitted, recalibration is not required providing the sensor body is not removed from its mounting bracket."
Theoretically, the car could be lifted by altering the length dimensions of the drop links. I'm not sure this is a good idea though. I'm not sure how much stress the CV joints can take raised and @ 65 mph. I'm not sure if the vehicle would have any uptravel left @ an extended height. I'm not sure if I could get any suspension repairs performed under warranty. In theory I think it could work.
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