this will be the best way to go about it

PINPOINT TEST O: THE COMPRESSOR IS INOPERATIVE
NOTE: This test is for the harness side of the relay circuitry.

Refer to Wiring Diagrams Cell 149, relay component for component testing.


Test Step Result / Action to Take
O1 CHECK AIR COMPRESSOR RELAY CONNECTOR
Disconnect: Air Compressor Relay C1000.
Inspect the pins of the air compressor relay connector for corrosion, bent or broken pins, moisture, or other damage.
Is the air compressor relay C1000 OK?
Yes
GO to O2.

No
REPAIR as necessary. TEST the system for normal operation.
O2 CHECK CIRCUIT 1053 (LB/BK)
Measure the voltage between air compressor relay C1000 pin 1, circuit 1053 (LB/BK), harness side and ground.
Is the voltage greater than 10 volts?
Yes
GO to O3.

No
REPAIR the circuit. TEST the system for normal operation.
O3 CHECK CIRCUIT 538 (GY/RD)
Disconnect: Air Compressor Assembly C194.
Measure the resistance between air compressor relay C1000 pin 5, circuit 538 (GY/RD), harness side and air compressor assembly C194 pin 4, circuit 538 (GY/RD), harness side.
Is the resistance less than 5 ohms?
Yes
GO to O4.

No
REPAIR the circuit. TEST the system for normal operation.
O4 CHECK CIRCUIT 577 (LG/RD)
Measure the resistance between air compressor assembly C194 pin 1, circuit 577 (LG/RD), harness side and ground.
Is the resistance less than 5 ohms?
Yes
RECONNECT air compressor relay C1000 and air compressor assembly C194. GO to O5 .

No
REPAIR the circuit. TEST the system for normal operation.
O5 CHECK AIR COMPRESSOR AFTER COOL DOWN PERIOD
Turn the air suspension service switch to the OFF position. Allow the vehicle to sit for 60 minutes to give the air compressor assembly time to cool off.
Turn the air suspension service switch to the ON position.
Ignition ON.
TRIGGER the 4WAS module vent on active command.
TRIGGER the 4WAS module compressor on active command.
Does the air compressor assembly run?
Yes
GO to O8.

No
GO to O6.
O6 CHECK AIR COMPRESSOR RELAY POWER
Disconnect: Air Compressor Relay C1000.
Measure the voltage between air compressor relay C1000 pin 2 circuit 577 (PK/LB), harness side and ground.
Is the voltage less than 10 volts?
Yes
GO to O7.

No
REPAIR circuit 577 (PK/LB). TEST the system for normal operation.
O7 CHECK AIR COMPRESSOR RELAY
Ignition OFF.
Connect a fused (50A) jumper wire (10 gauge) between air compressor relay C1000 pin 3, circuit 1053 (LB/BK), harness side and air compressor relay C1000 pin 5, circuit 538 (GY/RD), harness side.
Does the air compressor run?
Yes
DISCONNECT the jumper wire. INSTALL a new air compressor relay. TEST the system for normal operation.

No
DISCONNECT the jumper wire. INSTALL a new air compressor. REFER to Air Suspension Compressor in this section. TEST the system for normal operation.
O8 CHECK AIR COMPRESSOR THERMAL BREAKER
TRIGGER the 4WAS module LR and RR air spring solenoid valve open active commands.
Run the air compressor assembly for 60 seconds.
Did the air compressor assembly run for 60 seconds?
Yes
The thermal breaker was overheated. RETEST to validate the system is OK.

No
INSTALL a new air compressor assembly. REFER to Air Suspension Compressor in this section. TEST the system for normal operation.

 

When I replaced my wheel sensor my compressor would not kick on and the vehicle still sat weird. I disconnected the battery and then turned the key on and shorted the neg and pos wires together (remember battery disconnected) then turned off the key and reconnected the battery and hooray it started working like normal. The ride height was same as before on that corner so I may have gotten lucky, since the tech manual did say to recalibrate after sensor replacement.

 

good call you should clear the codes and see if that helps, sorry I'm used to working on these with a scan tool so that is automatic for me

 

Ok, I haven't been able to look at it for a couple of days, so I will get back it now. I did try the jumper wire last night over the relay. The compressor came back on, and I decided to let it run and see if it would air the tires up. Well the compressor ran for maybe a minute, before it blew the little fuse, but it never aired up the bags. Could this mean that my compressor isn't putting out air?

 

On mine, it seemed the shocks still need to get a signal from the computer to open the solenoid, to either let air in or out. So even with the compressor running if the solenoid is not open then nothing will happen inside the shock.

 

I can see that, but would it be all of them at once?

 

How old is this compressor, is it the original, how many miles are on it? Have you verified there are no leaks in the air lines? Did you check all the connections in the air lines to see if they are seated correctly?

 

It would only air the corner that needs air to get the truck level. If you had the tuck lifted the sensor sensed it and would only allow air through the ports that the computer told it to open. Jumping it shows that the compressor is working and it's time to look elsewhere for the problem.
The service manual says not to run the compressor for more than 3 minutes with a suitible time allowed for it to cool. When the system is right you should never hear it running fo more than about 2 minutes at a time.
I don't think you hurt anything, the fuse likely saved it. Now go back to work and find the cause.

 

I am assuming the compressor is the same from factory. The vehicl was built in April 03. I have not been able to trace the lines for leaks yet. I just found out today how to get it jacked up and have the suspension turned on, otherwise it has been way too low for me to get underneath.

The whole truck is down, not just one corner. The funny thing is the truck was fine when we parked it one night. I mean the driver front tire was up a little, but I knew that I needed to replace the height sensor. But when we went out in the morning the truck was slammed to the ground, and the compressor wouldn't even turn on. I was told I need to check next to see if the compressor is pushing any air out. Hopefully that will lead me to something.

 

I'm just thinking the compressor is worn down at this stage. At 115k miles, I'm on my third compressor. The factory version went out at around 62k and the replacement went even sooner, like around 105k, mainly because rear air springs and front air shock/springs developed micro cracks over time, they are made of rubber and are a wear item. Compressors have to labor hard and often to handle leaks. After a while, the internals of the compressor - piston and seals, valves, etc - start to wear faster and faster. Sure, the compressor might be able to come on and press up a little bit, but not enough to fill the system and hold it. After replacing it, I took my factory compressor apart to find the piston seals and bore were worn. Not worth rebuilding it, though, you can't find parts for it anyway, at least back then I couldn't. You can test the compressor to see if it is holding pressure to spec per manual. I documented it once here, this post will help you with weak LLS compressor and leak testing: https://www.ford-trucks.com/forums/9...ompressor.html

 

Yeah, I'm guessing it has been on there for roughly 95k, so it should probably be going out. But it sounds like it always have when I can get it to turn on. I do have one bag that looks different than the rest. Am I able to load a pic on this website. Maybe someone can tell me something about it. I have it jacked up right now, and that is the only bag that isn't fully extended I think.

 

I pulled the hose off of the dryer(i think)it is black with a orange top, and then I jumped the compressor and there was no air coming out of the line. Is this right?

 

... well, if the line is pulled out of the dryer, how's it supposed to get air? I really don't get what you are trying to do...

 

I was meaning that the compressor isn't building an air pressure. Isn't there supposed to be something coming out of that line?

 

the best and easiest place to disconnect the line is at the spot under the brake booster