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Jon D
Jon D, ASE Parts Specialist
Category: Lincoln
Satisfied Customers: 45
Experience:  7 years experience in retail parts
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I own a 2003 Lincoln navigator. I just had the air ride

Customer Question

I own a 2003 Lincoln navigator. I just had the air ride suspension converted to 4wheel coil over struts by a local mechanic. Problem is, the variable assist power steering no longer works. Took my nav to the local Ford/Lincoln dealership (where I purchased the vehicle brand new). Was told the local mechanic did not leave the solenoids attached and that putting them back on might solve the problem. It did not! Now they are saying that the air ride module and compressor are bad and will have to be replaced AND they will have to reinstall the air bags in order to solve the power steering problem???
Submitted: 1 year ago.
Category: Lincoln
Expert:  Jon D replied 1 year ago.

Short answer is, yes. The variable assist power steering on the navigators with air ride suspension is controlled by the air ride module. Who ever did the conversion for you should of let you know that by doing so, would take it away and leave it much harder to turn. Here is a little something from ford that helps to explain it.

For vehicles equipped with air suspension and VAPS, the electronics for both systems are contained in the air suspension module.

The air suspension control module outputs a pulse-width modulated (PWM) current to the control valve actuator. The control valve actuator controls the hydraulic valve that determines the amount of hydraulic assist provided to the steering gear. The amount of assistance provided varies with the control valve actuator current, which is based on vehicle speed according to a look-up table internal to the module. The amount of hydraulic steering assistance provided by the VAPS subsystem is proportional to the average control valve current.

The vehicle speed is provided to the air suspension module by the PCM over a dedicated vehicle speed signal circuit, this circuit also provides the vehicle speed information to other modules. The air suspension module also receives engine RPM information from the PCM but this information is sent over the universal asynchronous receiver-transmitter (UART) based protocol (UBP) communications network.

Basically, the pcm gives the air suspension module information, which in turn controls a control valve actuator that gives you your power assist. No air suspension module, no assist.