04 navigator air to coil suspension conversion

[Fordgirl01]

I’ve read through all posts I could find relating to this subject and found other internet posts as well. I think I have found the answer I was seeking, but I want to run it by all of the knowledgeable folks here to be sure!

I am going to convert my 04 when the weather warms up. The air system still functions, but I don’t really like it and it is not working like it should.

I am looking at the kit from strutmaster. The basic kit is $299 but they offer one with a module for an extra $300. All kits come with instructions to disable the warning light. So I questioned what the module does. Their chat rep basically just said the instructions for my 04 just stated to install the module to disable warning light, but couldn’t tell me what the module actually did. That answer was not good enough for me-I needed to know what the module did and was it worth an extra $300.

So I finally stumbled onto a post that explained the steering assist and how the control for that is in the same module as the air suspension. So if you disable the warning light and turn off the air suspension, the steering assist is also disabled.

With this information, I assume the strutmaster module bypasses the air suspension to disable the warning light but allows you to leave the switch on for the steering assist. Does this sound right?

So if the warning light doesn’t bother me and I wanted to keep $300 in my pocket for more important things....could I just install the basic kit and leave the air switch on?? Would the steering assist function properly and the only drawback be the warning light?


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[TobyU]

What is this steering assist you speak of?
I have an 03 and I thought 03-06 are basically the same. Just the engine transmission changes. That's why I specifically decided I had to have it 03 or 04. I would not have an 05 because of the three valve and I would not have an 06 because of the 6-speed transmission.

 

[Fordgirl01]

I found this thread about someone asking about doing the conversion on an 04. They were asking about steering issues.

The link for the thread is:
https://www.justanswer.com/ford-lin...oose-a-problem-power-steering-noticeable.html

Here is the part about steering assist:

“Variable Assist Power Steering (VAPS)
Navigator vehicles include a variable assist power steering (VAPS) system that controls the level of power assistance available to the driver based on vehicle speed. Below 3.2 km/h (2 mph), full power steering assist is provided to lessen steering efforts and increase maneuverability. Between 3.2 km/h (2 mph) and 191 km/h (119 mph), steering assist will decrease gradually at a calibrated rate to raise steering efforts for increased directional stability and greater road feel. Above 191 km/h (119 mph), steering assist is constant.

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.

When whomever disabled the air bags as well as the air bag module however they did so they also disabled the variable assist power steering which is a pressure control actuator mounted on the steering gear which adjusts the pressure of the hydraulic fluid going into the rack and pinion. This is why the steering effort has increased because the actuator has defaulted to more effort required.”


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[Fordgirl01]

I’m thinking the steering assist is on the 03 and 04. Strutmasters conversion kit is for 03-06, but there is a kit with the bypass module for 03-04.


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[lvcjt702]

I've converted my wifes 04 Gator to an all Rancho quicklift/puck setup with no adverse effects to the steering. She just has to turn the airbag warning off when she starts the truck. YMMV.

My suggestion would be to run the truck until the airbags are full then turn it off. Turn the air suspension switch to the off position. Restart.Then drive the truck around the block and see if your steering is affected.

Please report back with your findings.

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[Fordgirl01]

When you converted it I assume you didn’t bypass the warning light since you reset it each time. I also assume you left the switch on for the air? Mine lowers when I stop and get out. So if I let the air inflate then stopped to turn off the switch, it would probably be squatted down and handle funny anyway. I will try that anyway and see if I can notice a difference. I’m used to my old 99 anyway that rocks and rolls around like a big old boat (it has been converted and probably needs new shocks by now)! If the steering difference in the 04 is subtle-I won’t even notice!


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[lvcjt702]

Nope. The switch is left in the off position.

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[TobyU]

Kind of like the old town cars have the three position switch on the dash. I wasn't aware that Navigator did it automatically. I guess it makes sense as some of the trucks have a lot of issues with the power steering being hard when you're barely moving anyways and some people like a little bit more feel at speed on the highway. I don't really care. I used to drive a 67 GTO and it was the best power steering I've ever seen on a car. You could drive it at all time with your pinky and I don't need any feedback and performance style steering from a luxury vehicle.
The 03 to 06 Navigator does squat down a little over an inch when you get out but that only does it when you turn the key off. So you could leave yours running after it's aired up get out turn off the switch and then restart it or whatever and see if the steering is different.