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I thought I would share this thinking it could be helpful for others.....
Background: 2004 XJR, 115 kMi, four height sensor system, stock air suspension, have replaced front air springs and wabco compressor several years ago.
Last month the front of the car lifted to max height. The rear was normal. Hoping it was a glitch I drove it a few days but the problem continued. I scanned for codes with my Foxwell NT510 - no ASM codes reported. I used the Live Data feature on the Foxwell to verify reservoir and airspring pressures, solenoid valve positions, battery voltage, height sensor supply voltages, compressor status, etc. The only thing that appeared odd was a height sensor showing a value of " -32 ". So I decided to cycle the car through the ASM modes and see how the height sensor values responded. The table below summarizes my observations:
So now I'm really confused........ The " -32 " value seemed to be moving around on me.
A few days later I decided to monitor the height sensor response (Foxwell NT510, Live Data) when I depressed each corner. What I observed was response to all but the front right corner. I concluded there was probably a problem with the front right. First checked the wiring and connection, cleaned the connector but no improvement. I went ahead and replaced the height sensor; the new sensor arm moved smoothly through the entire range of motion. The old sensor was bumpy the entire range of operation. I intentionally did not disconnect the battery when I replaced the sensor.... the good news is the front immediately adjusted to the right height when set down. I've put ~ 100 Mi on the car since and everything seems to be working great.
Certainly there are other reasons for height adjustment problems on these cars but perhaps this can assist someone with troubleshooting.
Easy to check If you have a tool that offers 'Live Data' for the ASM. Just have someone watch the values for the height sensor positions while you (gentilly) depress and lift the car over each rear tire. If the 'Live Data' height position sensor varies then you know the sensor is at least not totally dead. In my case one sensor was totally unresponsive.
I'm assuming your ASM isn't throwing any DTC's. If it is I would start there. Good Luck hunting!.
My rear suspension is too high. Saturday, some rain got in when I opened the passenger door in a thunderstorm. On Monday, it suddenly started throwing dozens of error codes, and the rear suspension got rigor mortis, stuck in the fully-extended position, while the front did its best to amplify every jolt while driving.
When I got home, I recharged the battery. 2 days later, without the ignition having been switched on, the battery was low again. Obviously a short.
I pulled out the front seats, drained and dried the floor under the carpet, and charged up the battery.
On the bright side, most of the error codes went away, and I recovered almost a dollar in change and one house key from underneath the carpet.
But I still have:
C1881 front right height sensor -- short to ground / open circuit
C1893 rear left height sensor -- short to ground / open circuit
... and the rear shocks are still at maximum extension:
Oddly, the terrible jolting has gone away! It's still a /bad/ ride, for a Jaguar, but it isn't like riding a bucking bronco anymore.
But I'm still afraid to drive it, because I'm afraid the shock accordions will blow when they hit a bump and can't release any air.
Is that a reasonable worry?
I will test the sensors, but I don't think this is a sensor problem. I think it's a short caused by the rainwater, or maybe something that broke because I drove the car 140 miles with it jolting violently due to the shocks not moving.
Last edited by Xeno; Jul 23, 2022 at 12:29 PM.
Reason: add note about jolts being better
My rear suspension is too high. Saturday, some rain got in when I opened the passenger door in a thunderstorm. On Monday, it suddenly started throwing dozens of error codes, and the rear suspension got rigor mortis, stuck in the fully-extended position, while the front did its best to amplify every jolt while driving.
When I got home, I recharged the battery. 2 days later, without the ignition having been switched on, the battery was low again. Obviously a short.
I pulled out the front seats, drained and dried the floor under the carpet, and charged up the battery.
On the bright side, most of the error codes went away, and I recovered almost a dollar in change and one house key from underneath the carpet.
But I still have:
C1881 front right height sensor -- short to ground / open circuit
C1893 rear left height sensor -- short to ground / open circuit
... and the rear shocks are still at maximum extension:
Oddly, the terrible jolting has gone away! It's still a /bad/ ride, for a Jaguar, but it isn't like riding a bucking bronco anymore.
But I'm still afraid to drive it, because I'm afraid the shock accordions will blow when they hit a bump and can't release any air.
Is that a reasonable worry?
I will test the sensors, but I don't think this is a sensor problem. I think it's a short caused by the rainwater, or maybe something that broke because I drove the car 140 miles with it jolting violently due to the shocks not moving.
I'm having the same issue but only for the passenger side. This is the second time I've had this happen. The first time all four corners where up and hard as a rock. My mechanic could not really find anything and just did a reset. Both time it had rained real hard the night before. Going to get "fixed" again on Tuesday.
RESOLVED: Air Suspension - Front High
