Sorry for the delay.
I had more urgent issues to fix.
My 5-speed swap caused my PCM to freeze randomly, requiring a reboot every time it stalls. And it took quite some time to figure out what it was.
Thought it was caused by suspension as it only happened when car was fully loaded.
But no ; it was indeed caused by the 5-speed swap and unrelated to the suspension.



That being cleared out and fixed yesterday...
I should be able to resume troubleshooting of this issue shortly after Christmas.
Need to recuperate the parts of suspension (balloons + height sensor) which we have removed.
And need to have a lift available to work. Not going to troubleshoot that under the car with a floor jack.


With suspension disconnected, as well, as height sensor, the ON/OFF switch in trunk has no effect anymore.
Used to clearly say "Suspension Off" in the information center. Now it displays that suspension is defective regardless the position of the switch.
Suspension Defect : This comes back every 10 minutes in the cluster while driving. If you drive 35 minutes to get to work, light will appear 3 times during that time.
Suspension Off : This comes on only once per ignition cycle ; So as long as you don't restart the car, it's not going to appear again. Would still be an improvement to get the suspension Off message.


At the moment, whole system is kind of disabled, not responding.
Need to figure out what I need to connect back in order to have the ON/OFF switch working again.
Might need to install some load on the circuit to simulate presence of the 2 rear solenoids.
And resistance to simulate the height sensor.

However the height sensor has 2 outputs. 1 input and 2 outputs going back to the VDM box
Need to reverse engineer a bit to find out what that 2nd output is.

A minimum would be to disassemble the solenoids from the airbags and try to connect that alone. And connect height sensor.
See if the On/Off switch functionality comes back to normal.
Only then I can start to troubleshoot to bypass the height sensor.
I prefer to do that before to mess around with the wiring / cutting out stuff behind glove box.

So will keep posted in early 2017.
I'm motivated to get that stupid light Off and will find a solution, regardless how much it's gonna cost.

If it is wired the same way as the earlier cars, the air suspension switch in the trunk disconnects the power to the air height sensor. So the module still sees continuity in the sensor, but no signal from it. Its a hall-effect sensor, there are 4 wire in. 1 is 12v in, one is ground, and the other 2 are "ride height - high" and "ride height - low".

From the '98 service manual:
My understanding from this is that the module expects to see 12v on its "ground" from the sensor, as the sensor operates at various heights, the 12v will move to either the high or low inputs depending on suspension height. What the sensor calls a ground is not actually connected to ground, it runs straight to the module, so I'd call it a "ride height - level" input rather than a ground.

I think we cannot compare 07+ suspension with previous years.
What you just said does not match what I see on the wiring diagrams.
See file attached

I'd like to know what "BACKHT A" stands for. (VDM pin 1)

They must have changed the whole system sometime after '98...my 2003 manual shows a 3-wire system and says it operates on a voltage from approx 4.75V for LOW to 0.25V for HIGH. It does not specify a voltage for TRIM.

It's the ground side of the height sensor circuit. It's kept separate from power ground to eliminate any noise on the return line.

I understand that, I was just curious why they gave it such an odd name. In the 2003 FSM it's called SIG RTN.

BACKHT I suppose because it represents the rear (back) height (ht).

Technically the RETURN line (signal return) and BACKHT lines (signal ) are both 'ground', but it would be misleading to call either of them GND's...

Troubleshooted the CLUSTER now...
As the option to enable/disable the suspension feature seems to be stored in the cluster.
But nobody, even dealers will change that. Even if they had the tools to do so (IDS I believe).


Press and hold both buttons SELECT/RESET in the dash, then turn ignition switch to ON, and hold the buttons until diagnostic starts.
Self-diagnostics goes through all steps.
Facts I've noted down...


Returns DTCs D900 and E023 (seems undocumented)


"HW Input" shows "C0" in HEX


This is the value corresponding to what gets received by the CANBUS regarding:
- Brake Fluid Switch Status
- Park Brake Status
- Air Suspension (0 = Not Faulted / 1 = faulted)

"C0" HEX corresponds to 192 Decimal.
Not sure what that means.

>>Displays the hardwired telltale (brake fluid level status), (parking brake status) and (air suspension) status in hexadecimal.


My SCT OBDII shows no DSC related to the PCM. Even dataloging tools don't show those error codes.
Seems to be exclusive to the cluster.




Also the VDM has a diagnostic mode as well.
However it seems to require a special scanner to to read those.
For example C1964 would mean "Air Suspension Air Compressor Request Exceeded Maximum Timing"
C1885 would mean "Air Suspension RR Height Sensor Circuit Failure"
etc

Not sure if the error codes are stored in memory and stay there. Disabling the module until it reset by the dealer ??
My suspension system was still functional (But wouldn't say reliable after 3 compressor failures) before we removed it.
Why plugging back everything together would fail to work as normally ?

Found the answer to this question

The vehicle dynamics module (VDM) sends power to the height sensor along circuit 417 (VT/OG) and the voltage returns along circuit 432 (BK/PK). The sensor sends the position signal back to the VDM along circuit 427 (PK/BK).

That makes sense. I know the '03+ cars use a different sensor. If its 3-wire then its probably just a potentiometer like a TPS, it sends 5v out, and gets a <5v back that tells it where the suspension height is. Actually its probably simpler than the hell-effect system used on the '91-'02 cars, probably gives more accurate height feedback too as it seems my '97 varies its own set height by ~1/2" (just enough to be noticeable) at total random. Sometimes its too high, sometimes its too low. But its using a sensor from a '94 that isn't in the greatest condition.

I've never messed with RAS on a '03+. I've got plenty of experience with '94-'02 RAS, having fixed/overhauled/reinstalled several systems in those cars. The RAS its self is the same on any year that had it, but the electronics apparently changed more than I thought it did.

Yes

Bigmerc96, is it possible to replace the RAS wiring on an 05 lx sport without being a massI've overhaul and expensive project ? I have replaced nearly everything in my air ride except the module and wiring harness. Ford stealer ship points to bad ground somewhere...the inability to raise my car up got worse and worse, can't seam to tricon the car anymore....I am so frustrated. I am getting a used module sent to me. I want to keep the air ride, so I'm pushing on. (Without the support of my wife's)

"A man's gotta do what a man's gotta do."

(obligatory John Wayne reference)

Anyone know if I swap the RAS/VASP module behind the glove box, will I need the dealership to program or reflas it? Or can I plug and play, maybe disconnect the battery? It is my last attempt before I go to Strutmaster or Arnotts for conversion...leaning g towards Strutmasters.

Thanks,

Mike