Rear Suspension Down Air Ride Diagnosis

I just had one come in and made an easy to follow diagnostic video to see why that air compressor is not coming on and why your back end is down to the ground. Air ride truly is simple to diagnose and fix if you understand the system. This procedure applies to Expedition and Navigator pre 2003. Hope this helps!

Ford Air Ride Rear Suspension Down Diagnosis - YouTube

Great video. Again.

This is three weeks late for me, but luckily I figured the problem out otherwise. I found conflicting part number information on the replacement relay. Details in my post in this thread:

http://www.expeditionforum.com/f42/...sion-compressor-relay-relay-12039/#post184078

The compressor has been running normally since the relay change out. Very consistent and the system is holding air through this winter's sporadic single digit temperatures.

Re: Rear Susp Low...

I found your vid yesterday and it helped a great deal. I am going to describe my issue based on your video.

1. compressor is new and verified working by direct connect to battery.
2. tested the relay plug as per your video. Load test on small wire with 12v air compressor
3. Replaced relay. No Joy.

Now for the history. For the last few months the air susp has been working but with the following issues. While driving, the compressor would come on very often. After about 20 minutes, the "chk Susp" light would come on. The susp would stay at height and not sag. If I had passengers, the system would do as above but not always get the "chk susp" light. When passengers debarked, she stayed up and even a bit higher without the weight. When parking after the light comes on the Exp would stay up. When I start it up the next day there was no initial leveling and the light would not come on until the compressor and had been cycling on and off over the next 20 mins or so.

While I have heard an occasional hissss coming from the drv/rear susp when it is not running, the Exp would always and I say again ALWAYS be in the up position and stay there when the "chk susp" light would come on.

As per your video, the compressor is not coming on and the rear end is down. I am thinking that there is no signal from the control unit due to it being bad or the control unit is not getting a signal from the level sensor.

Your thoughts on this issue are greatly appreciated and if you feel I should post this in the "Suspension" thread, I will...

Thanks a bunch!

Year?

If you bypassed the relay and the compressor started, it seems that you've isolated the relay.

Remember that the truck doors need to be closed for the air ride system to function.

Check the height sensors. These are known to slip out of adjustment.