Air suspension

C1725 - Air Suspension Front Pneumatic Failure

Solenoids are easy to test. Apply twelve volts to open them and if air goes in/out they are okay.
For testing you really need the DRBIII factory tool. It has all of the items in it including tests that cycle the suspension and that can read all of the factory data. Very few of the aftermarket units can do that, especially with the air suspension because it is not a real common failure item. In this case a dealer or shop that has the DRBIII would be the best thing, even if you only pay them to diagnose the system.

Dorman = OEM is like saying Rosie O'Donnel is the same in a boxing match as Mike Tyson.

I would test those sensors first, I doubt that both went bad at the same time. I would suspect the wiring or the VDM. The best way to test it is with the proper scan tool.

I misspoke about that tool though, It is not the DRBII for the Ford/Lincoln/Mercury line, Had a different vehicle on my mind, Sorry. F/L/M uses the IDS tool.

The scan tool can make the VDM enter a self test mode where it tests the sensors and itself.

To test the sensors on the vehicle you will need a multi-meter and either some back probe pins (dressmaker T pins work good for this) or some insulation piercing probes (just seal the tiny hole with some liquid electrical tape)

Disconnect the actuator levers from the arm. You will be moving the sensor arm itself. Remove fuse 111 (powers the compressor, you do not want the thing to suddenly pop into the air while you work on it)

Pick a sensor. Both sides use the same colors for ground and power. Ground is a black wire with a pink stripe and power is the red wire with a black stripe.
The left side uses a pink wire with a black stripe as the signal wire, the right side uses a Tan wire.

On the ground wires you should see no voltage when the system is on.
On the power wires there should be a constant five volts.

When you test the signal wires, connect one side of the meter to ground and the other to the wire. As you move the sensor arm the voltage should smoothly increase and decrease from about.50 volts to about 4.5 volts.

If you lack the power signal verify that fuse 30 and fuse 27 are OK. If they are then locate the VDM and test the same colors there, That way you can find out if it's a broken wire between the VDM and the sensors.
If you lack the ground side check the ground connection for the VDM, it is behind the left kick panel in the drivers foot-well. Check it at the VDM as well.

If the sensors test okay re-connect the arms and move to the air solenoids.

These are nothing but simple coils. The black wire grounds the front ones at the right side of the radiator (where the compressor also grounds so maybe check that first as rust/broken wires could be causing both issues) and the other wire powers them. To test them, unplug them and simply run a pair of jumper wires down and touch the terminals on the solenoids. Do not hold the wires on them, you are just testing them, a quick click should mean they are Okay.

If they test okay re-connect them and move to the compressor relay, From it you can test the compressor. Plug fuse 111 back in. Check the relay, it should have twelve volts at the light blue with pink stripe, ground at the black wire. The gray wire with a red stripe carries power to the compressor. The dark blue with yellow stripe is the on/off signal from the VDM. If you apply twelve volts to the gray wire with red stripe the compressor should engage and pump air.

You have now tested every part but the VDM, Hopefully you found the bad ground or power connection causing the problem. Otherwise you will need to get to a dealer and see if they can scan and test the VDM.
The wiring diagram might help.

I wouldn't use 12 volts. They are a simple position sensor and 12 volts might burn the actual potentiometer. 3 common 1.5 volt D/C/AA batteries in series would give you a 4.5 volt source. That should work for testing. What you are looking for is a smooth rise/drop in voltage as you move the arm.

The suspension compressor is run by the relay near the right headlamp, the wire colors are- lt blue/pink, lt grn/red, gray/red, dk blue/yellow. Find the relay and test for power at lt blue/pink, gray/red, if ok then test for ground at lt grn/red, dk blue/yellow. If all ok then check for power at the red at the motor and ground at the black and get back to me

Look at the connector on one on the truck, then the wiring diagram to tell which pin is power in. I would say you could do a resistance check as well but I don't see the specs for good/bad

Need to know if the check air suspension light is on? How many miles are on the truck?

Good morning,

Do you have a voltmeter to do some checks?

I attached the wiring diagram for you to view. You have thrown a lot of parts with no results here so it is time to do a diagnostic to verify the failure.

You need to go to the relay and verify power to the relay. The diagram I attached has three powers for the system. Verify power on both side of the fuses at the fuse block.

Yes, the car door has to be closed. When you start it, the compressor should kick on as a self test for the system.

Roy

I understand.

Taped wires are never good and need to be repaired correctly.

When you went to level ground, did the suspension pump back up?

Roy

I doubt reprogramming the module will help.

You need to have someone look at this with a scan tool that can turn the system on and off and monitor all the data. I cannot tell from here what is going on unless I am there to physically check it.

Roy