I picked up a 1998 Navigator with 4-way air suspension that doesn’t work. The compressor will not turn on but I have verified that it does work, also I know that it is fairly new. I tested the front and rear height sensors and both tested good: (voltage was between the specified .25 and 4.75 volts). I was certain the compressor relay was bad because I jumped wires to it to try and manually make the system kick on but it still didn’t work. I bought a new relay and still nothing happens. Something I find kindof odd is that I am getting like 5volts at the compressor/pump connector which supplies the pump with power from the relay (I have a wiring diagram) This should be 12V and I believe it should be 12V when the compressor is switched on from the system, am I correct here? Yes, the doors are closed, the switch is on, I’ve shift it to Drive and Reverse, tried all the 4WD options, prayed… and still nothing. I’m out of ideas here.

Is it possible that the Suspension Control Module in the dash is shot? How often are these known to fail? Another problem I should mention is that when the truck is warmed up the gauges read all sorts of crazy things, like Oil Pressure, Temp and Volts Maxed out even though I’ve verified that I’m getting 14.2 volts at the battery and I know there’s no way the truck is overheating (it happens after about 5 minutes of running). Could I have a faulty alternator and is it possible this is affecting the air suspension system???

I know I should swap it to standard suspension but I want the air suspension and I know it will probably break again but oh well… it’s cool, not to mention I refuse to be beaten by it. Does anyone know anywhere I can rent the NGS Scanner from to diagnose this easily? I’m sure I will get raped if I bring it to Ford for diagnosis/recalibration/whatever.

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ANY help would be greatly appreciated. Thanks,
Jason

 

It's very possible that your other electrical issues are also causing the Air Suspension problem. Very often weird electrical issues like you are having are caused by poor or missing grounds. If you have the factory service manual, look to see if any of the affected systems share the same ground point (Gauge Cluster, AS Module, etc). Methodically clean and tighten ALL of the grounds under the hood and in the interior. Make sure the engine to body grounds are secure.
It sounds like yiu have a system that's just waiting to be told what to do but the boss (Suspension Controller) is not around to tell it what to do. The controller isn't doing it's job for some reason. The controller "can" fail just like any other part, but I've never seen one do so. The problem is more likely a missing input (door switch, ignition on, etc) or a power/ground issue to the controller. At this point, my money is on a bad ground due to the other issues you have.