The Caddy has been riding poorly lately. I think the gas shocks have lost most of their air. I have two DTC's set. C 1738 and C1711. C1738 is Exhaust Solenoid Short to Ground. C1711 is LF Damper Actuator Short Circuit to Ground.
After going through the diagnosis steps in the shop manual, I have discovered that I have an electrically open Exhaust solenoid which is located in the Automatic Level Control (ALC) compressor pump head . (See Schematic below)
It appears as a 'short to ground' because when the exhaust solenoid controller located in the Continuously Variable Road Sensing Suspension (CVRSS) module tests for voltage, it reads low because it is not connected due to the open exhaust solenoid in the ALC compressor head.
My first thought was to replace the OEM shocks with Monroe (as suggested elsewhere here), but that would mean giving up the variable rate OEM shocks. I have tested the airshocks, and the compressor, and both appear to be working. I did this by manually connecting the control side of relay 55 located in the Rear Junction Box (fuse panel) to ground which turns the compressor on (ELC relay in the schematic). Yes it is ELC in some places and ALC in others??
So my next thought was perhaps I can fool the logic by connecting a resistor across the exhaust valve solenoid in the compressor head (i.e., C to A on the ALCC in the schematic). The exhaust valve would still be inoperative, but it would allow the pump to raise the vehicle. It should also allow the CVRSS to work properly. The downside is that it will not automatically vent air from the shocks when the load is removed.
The long-term fix would be to replace the compressor with an Arnott unit. It does appear that they have one specifically for my vehicle.
Does anyone have any idea what the approximate resistance value of the exhaust solenoid in the compressor head is? Mine is currently infinite, or at least very large. My plan is to begin with a 1kohm resistor, since this would dissipate less than 1/4 watt at 14v. If this allows me to clear the DTC, then we will go with it.
Stay tuned!
After going through the diagnosis steps in the shop manual, I have discovered that I have an electrically open Exhaust solenoid which is located in the Automatic Level Control (ALC) compressor pump head . (See Schematic below)
It appears as a 'short to ground' because when the exhaust solenoid controller located in the Continuously Variable Road Sensing Suspension (CVRSS) module tests for voltage, it reads low because it is not connected due to the open exhaust solenoid in the ALC compressor head.
My first thought was to replace the OEM shocks with Monroe (as suggested elsewhere here), but that would mean giving up the variable rate OEM shocks. I have tested the airshocks, and the compressor, and both appear to be working. I did this by manually connecting the control side of relay 55 located in the Rear Junction Box (fuse panel) to ground which turns the compressor on (ELC relay in the schematic). Yes it is ELC in some places and ALC in others??
So my next thought was perhaps I can fool the logic by connecting a resistor across the exhaust valve solenoid in the compressor head (i.e., C to A on the ALCC in the schematic). The exhaust valve would still be inoperative, but it would allow the pump to raise the vehicle. It should also allow the CVRSS to work properly. The downside is that it will not automatically vent air from the shocks when the load is removed.
The long-term fix would be to replace the compressor with an Arnott unit. It does appear that they have one specifically for my vehicle.
Does anyone have any idea what the approximate resistance value of the exhaust solenoid in the compressor head is? Mine is currently infinite, or at least very large. My plan is to begin with a 1kohm resistor, since this would dissipate less than 1/4 watt at 14v. If this allows me to clear the DTC, then we will go with it.
Stay tuned!
