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air suspension problem

rford

Certified Ford Tech
9
0
Pa.
My 2000 expedition will trip ck susp light when idling sitting still for about 4-5 minutes, during this time compressor cycles on / off before tripping light.
Most recent condition is that when riding down the highway the ck susp light will come on and the rear susp will drop slowly in about 3-4 miles while traveling @ about 60mph.
I can start vehicle on level ground and it will lift up and maintain height, if I put weight on each corner the compressor will cycle on / off as weight is applied then removed.
Vehicle will sit all night and not drop. I see 3 height sensors one on the rear susp and one on each front and they are properly connected.

Any advice on troubleshooting & testing to determine faulty part would be of great help.
Thanks!
 

blacksnapon

Moderator
Staff member
My 2000 expedition will trip ck susp light when idling sitting still for about 4-5 minutes, during this time compressor cycles on / off before tripping light.
Most recent condition is that when riding down the highway the ck susp light will come on and the rear susp will drop slowly in about 3-4 miles while traveling @ about 60mph.
I can start vehicle on level ground and it will lift up and maintain height, if I put weight on each corner the compressor will cycle on / off as weight is applied then removed.
Vehicle will sit all night and not drop. I see 3 height sensors one on the rear susp and one on each front and they are properly connected.

Any advice on troubleshooting & testing to determine faulty part would be of great help.
Thanks!
First step......high end scanner to read suspension dtcs.
 

blacksnapon

Moderator
Staff member
Suspension Control Module Diagnostic Trouble Code (DTC) Index

Air Suspension Control Module Diagnostic Trouble Code (DTC) Index

DTCs Description Source Action
B1318 Battery Voltage Low Air Suspension Control Module GO to Pinpoint Test C.
B1342 ECU Is Defective Air Suspension Control Module REPLACE the air suspension control module. RESET front height; REFER to Front Ride Height Resetting — Clear B2140 DTC. TEST the system for normal operation.
B1485 Brake Pedal Input Circuit Battery Short Air Suspension Control Module RERUN On-Demand Self-Test; MAKE SURE that the brake pedal is not pressed. If the DTC is returned again, REPAIR the brake pedal position circuit.
B1566 Door Ajar Circuit Short to Ground Air Suspension Control Module GO to Pinpoint Test D.
B1749 Park/Neutral Switch Circuit Failure Air Suspension Control Module GO to Pinpoint Test E.
B2140 Initialization Failure (Vehicle Ride Height Not Programmed) Air Suspension Control Module REFER to Front Height Resetting — Clear B2140 DTC.
C1439 Vehicle Acceleration EEC-IV Circuit Failure Air Suspension Control Module GO to Pinpoint Test F.
C1724 Air Suspension Height Sensor Power Circuit Failure Air Suspension Control Module GO to Pinpoint Test G.
C1725 Air Suspension Front Pneumatic Failure Air Suspension Control Module GO to Pinpoint Test H.
C1726 Air Suspension Rear Pneumatic Failure Air Suspension Control Module GO to Pinpoint Test I.
C1756 Air Suspension Front Height Sensor High Signal Circuit Failure Air Suspension Control Module GO to Pinpoint Test J.
C1760 Air Suspension Rear Height Sensor High Signal Circuit Failure Air Suspension Control Module GO to Pinpoint Test J.
C1770 Air Suspension Vent Solenoid Output Circuit Failure Air Suspension Control Module GO to Pinpoint Test K.
C1790 Air Suspension LR Air Spring Solenoid Output Circuit Failure Air Suspension Control Module GO to Pinpoint Test L.
C1795 Air Suspension RR Air Spring Solenoid Output Circuit Failure Air Suspension Control Module GO to Pinpoint Test M.
C1830 Air Suspension Compressor Relay Circuit Failure Air Suspension Control Module GO to Pinpoint Test N.
C1845 Air Suspension Front Inflator (Fill) Solenoid Output Circuit Failure Air Suspension Control Module GO to Pinpoint Test O.
C1865 Air Suspension Rear Inflator (Fill) Solenoid Output Circuit Failure Air Suspension Control Module GO to Pinpoint Test P.
C1869 Air Suspension Gate Solenoid Output Circuit Failure Air Suspension Control Module GO to Pinpoint Test Q.
C1917 Steering EVO Out-of-Range Fault Air Suspension Control Module REPAIR the steering system. REFER to Section 211-00.
P1807 4x4 High Indicator Circuit Short to Ground PCM GO to Pinpoint Test R.
P1808 4x4 Low Indicator Circuit Short to Ground PCM GO to Pinpoint Test R.
 

rford

Certified Ford Tech
9
0
Pa.
air suspension

Thanks Blacksnapon,
A friend and I scanned dtc and found c1830, cleared code and retested vehicle, same code returned. After commanding rear vent, vehicle dropped and then compressor would not operate. I jumped out relay behind headlight and no compressor operation. I replaced compressor and still will not operate. Tested new compressor by jumping out relay and new compressor will operate but vehicle did not lift up. We are going to scan again as we ran out of time that evening. Again thanks for your help.
 

blacksnapon

Moderator
Staff member
PINPOINT TEST N: DTC C1830 — AIR SUSPENSION COMPRESSOR RELAY CIRCUIT FAILURE
CONDITIONS DETAILS/RESULTS/ACTIONS
N1 VALIDATE DTC C1830 ERROR

Carry out the air suspension control module On-Demand Self-Test.


Is the same air suspension DTC set?
Yes
GO to N2.

No
If no DTC is retrieved, GO to N6. If a different DTC is retrieved, REFER to Air Suspension Control Module Diagnostic Trouble Code (DTC) Index.
N2 CHECK AIR COMPRESSOR RELAY CONNECTOR


Turn the air suspension switch to the OFF position.


Air Compressor Relay C1000

Inspect the pins and terminals of the air compressor relay for corrosion, bent or broken pins, moisture, or other damage.


Is the connector OK?
Yes
RECONNECT air compressor relay C1000. GO to N3.

No
REPAIR as necessary. TEST the system for normal operation.
N3 CHECK AIR COMPRESSOR PID
Turn the air suspension switch to the ON position.



Select air suspension control module active commands and activate PID AS_COMP.

Trigger active command COMPRESSR ON and OFF.


Do the letters O or B appear next to the ON/OFF text for the air compressor?
Yes
If O appeared, GO to N4.

If B appeared, GO to N7.

No
GO to N8.
N4 CHECK CIRCUIT 577 (LG/RD)


Turn the air suspension switch to the OFF position.


Air Suspension Relay C1000


Measure the resistance between air compressor relay C1000 pin C, circuit 577 (LG/RD), harness side and ground.


Is the resistance less than 5 ohms?
Yes
GO to N5.

No
REPAIR the circuit. TEST the system for normal operation.
N5 CHECK POWER TO AIR SUSPENSION RELAY

Measure the voltage between air compressor relay C1000 pin A, circuit 1053 (LB/PK), harness side and ground.


Is the voltage greater than 10 volts?
Yes
GO to N6.

No
REPAIR the circuit. TEST the system for normal operation.
N6 CHECK CIRCUIT 420 (DB/YE)


Air Suspension Control Module C296


Measure the resistance between air suspension control module C296 pin 18, circuit 420 (DB/YE), harness side and air compressor relay C1000 pin D, circuit 420 (DB/YE), harness side; and between air suspension control module C296 Pin 18, circuit 420 (DB/YE), harness side and ground.


Is the resistance between the air suspension control module and air compressor relay less than 5 ohms, and between the air suspension control module and ground greater than 10,000 ohms?
Yes
REPLACE the air suspension relay. TEST the system for normal operation.

No
REPAIR the circuit. TEST the system for normal operation.
N7 CHECK CIRCUIT 420 (DB/YE) FOR SHORT TO POWER


Turn the air suspension switch to the OFF position.


Air Compressor Relay C1000



Air Suspension Control Module C296

Turn the air suspension switch to the ON position.



Measure the voltage between air suspension control module C296 pin 18, circuit 420 (DB/YE), harness side and ground.


Is the voltage greater than zero volts?
Yes
REPAIR the circuit. TEST the system for normal operation.

No
REPLACE the air suspension control module. SET the ride height; REFER to Front Ride Height Resetting — Clear B2140 DTC. TEST the system for normal operation.
N8 CHECK CIRCUIT 420 (DB/YE) FOR SHORT TO GROUND


Air Suspension Module C296



Air Suspension Relay C1000


Measure the resistance between air suspension module C296-18, circuit 420 (DB/YE) harness side and ground.


Is the resistance greater than 10,000 ohms?
Yes
GO to N9.

No
REPAIR circuit 420 (DB/YE). TEST the system for normal operation.
N9 CHECK AIR SUSPENSION RELAY FOR INTERNAL SHORT TO GROUND


Air Suspension Relay C1000


Measure the resistance between air suspension control module C296-18, circuit 420 (DB/YE) harness side and ground.


Is the resistance greater than 10,000 ohms?
Yes
INSTALL a new air suspension control module. REFER to Module — Air Suspension Control in this section. TEST the system for normal operation.

No
INSTALL a new air suspension relay. TEST the system for normal operation.
 

rford

Certified Ford Tech
9
0
Pa.
thanks for the troubleshoot info. I will check some more tomorrow. I checked relay wires and am not getting a ground signal from the module wire.
 

rford

Certified Ford Tech
9
0
Pa.
Hey Blacksnapon,
Checked out relay wiring today found that I do have 4.96 volts on command wire from module and found hot looking relay power terminal, replaced relay, still no compressor operation. Further checking and found that power supply terminal on relay plug was not making contact to new relay. Pinched down terminal and all is operational. I will get and replace the relay pigtail tomorrow. also cleared code and ran test again all clear.
Thanks again for your help this one had me scratching my head a bit.
 

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