Town Car air suspension height sensor replacement and adjustment

[Town]

The 2003 and up Town Car models use a single height sensor mounted to the left lateral watts linkage (in front of the rear axle on driver's side) and the frame above the rear axle. Ford calls it a rotary height sensor to differentiate it from the earlier Town Car models that used a straight telescopic sensor. Once the sensor is adjusted for the car then there is usually no need to adjust it again. So it is expected that these procedures will be needed in conjunction with replacing the height sensor.

Attached is the procedure to replace the height sensor on a 2006 model that should be the same from 2003 through 2011 models.

The suspension ride height is measured between the top of the axle under the frame to the underside of the frame. The distance is approximately 4.75" although 4.5" to 5" is within tolerance. This height will be about 29.25" from the underside of the rear fender to the ground with the car unloaded on a flat surface. The actual specifications are given in the attached document.

To adjust the suspension height you just adjust the position of the height sensor according to the attached adjustment procedure. Since you are unlikely to have the special tool to measure the distance from axle to frame underside and the sensor voltage you will be limited to using a tape measure for the distance and making adjustments on the sensor mounting bolts and checking the resulting ride height once the suspension has adjusted itself to that sensor height setting. It may take several ties to get it right.

Be very careful with each step to switch off the air suspension before working on the car and switch it back on once clear of the car to check your result.

Good luck.

 

[Town]

1998 to 2002 Town Car air suspension height sensor adjustment

The 1998 and up to 2002 Town Cars use a straight height sensor. If it is being replaced then it needs to be adjusted to the marked position of the old sensor or adjusted according to the attached procedures. Sometimes the height sensor can get folded over and prevent the suspension from raising to trim height.

Replace the ride height sensor according to the attached replacement procedure. Adjust the position of the ride height sensor according to the attached ride height adjustment document. The rear suspension ride height is given in the attached specs document. It is 5" plus or minus 0.3". That is the measurement from the top of the axle tube to the underside of the rail tube immediately over the axle. Since electronic tools to plug into the air suspension module are not expected to be available the adjustment of ride height will be by trial and error. There is an allowance of a half inch in the height of the rear fender lip (at the axle center line) to the ground comparing left to right sides.

Good luck.

 

[24000rpm]

Town, when you are adjusting the height, you are talking about the height on both sides , correct?
there's no way you can adjust just one side and leave the other side alone, I suppose?

The 2003 and up Town Car models use a single height sensor mounted to the left lateral watts linkage (in front of the rear axle on driver's side) and the frame above the rear axle. Ford calls it a rotary height sensor to differentiate it from the earlier Town Car models that used a straight telescopic sensor. Once the sensor is adjusted for the car then there is usually no need to adjust it again. So it is expected that these procedures will be needed in conjunction with replacing the height sensor.

Attached is the procedure to replace the height sensor on a 2006 model that should be the same from 2003 through 2011 models.

The suspension ride height is measured between the top of the axle under the frame to the underside of the frame. The distance is approximately 4.75" although 4.5" to 5" is within tolerance. This height will be about 29.25" from the underside of the rear fender to the ground with the car unloaded on a flat surface. The actual specifications are given in the attached document.

To adjust the suspension height you just adjust the position of the height sensor according to the attached adjustment procedure. Since you are unlikely to have the special tool to measure the distance from axle to frame underside and the sensor voltage you will be limited to using a tape measure for the distance and making adjustments on the sensor mounting bolts and checking the resulting ride height once the suspension has adjusted itself to that sensor height setting. It may take several ties to get it right.

Be very careful with each step to switch off the air suspension before working on the car and switch it back on once clear of the car to check your result.

Good luck.

 

[Town]

Town, when you are adjusting the height, you are talking about the height on both sides , correct?
there's no way you can adjust just one side and leave the other side alone, I suppose?

Yes the height sensor is for both sides so the height sensor covers both air springs. Your difference in height on rear suspension is likely due to:
1. uneven surface when measuring;
2. a front suspension coil spring fracture or similar;
3. a stuck air spring solenoid valve (with suspension switch on raise the rear of the car until the venting stops then lower the car, a stuck solenoid valve will keep air in that spring so height difference will be reversed);
4. blocked balance hose between the two rear air springs (same test as 3, but may not be completely blocked so do the test quickly and don't wait for complete venting);
5. weaker rubber in one spring compared to the other (measure diameter of each spring while loaded).



Measure from the ground to the underside of the wheelarch on the wheel centerline for all 4 wheels. Ensure the bodywork is in good condition for those measurements. Compare side to side measurements for the imbalance, where a half inch difference is considered normal.

Good luck.

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[Coodeville]

How much should you move the sensor when you adjust it? My suspension was way up with the measurement from the ground being 32". I moved the sensor about 1/8 of an inch and it dropped to 28 ". Im thinking this is a very sensitive sensor adjustment

 

[Mikeswhite]

1998 to 2002 Town Car air suspension height sensor adjustment

The 1998 and up to 2002 Town Cars use a straight height sensor. If it is being replaced then it needs to be adjusted to the marked position of the old sensor or adjusted according to the attached procedures. Sometimes the height sensor can get folded over and prevent the suspension from raising to trim height.

Replace the ride height sensor according to the attached replacement procedure. Adjust the position of the ride height sensor according to the attached ride height adjustment document. The rear suspension ride height is given in the attached specs document. It is 5" plus or minus 0.3". That is the measurement from the top of the axle tube to the underside of the rail tube immediately over the axle. Since electronic tools to plug into the air suspension module are not expected to be available the adjustment of ride height will be by trial and error. There is an allowance of a half inch in the height of the rear fender lip (at the axle center line) to the ground comparing left to right sides.

Good luck.

What part of this procedure applies to adjustment, r&r and specs with some crazy computer commands. is it adjustable or not appears not to be

 

[c aphook48]

1998 to 2002 Town Car air suspension height sensor adjustment

The 1998 and up to 2002 Town Cars use a straight height sensor. If it is being replaced then it needs to be adjusted to the marked position of the old sensor or adjusted according to the attached procedures. Sometimes the height sensor can get folded over and prevent the suspension from raising to trim height.

Replace the ride height sensor according to the attached replacement procedure. Adjust the position of the ride height sensor according to the attached ride height adjustment document. The rear suspension ride height is given in the attached specs document. It is 5" plus or minus 0.3". That is the measurement from the top of the axle tube to the underside of the rail tube immediately over the axle. Since electronic tools to plug into the air suspension module are not expected to be available the adjustment of ride height will be by trial and error. There is an allowance of a half inch in the height of the rear fender lip (at the axle center line) to the ground comparing left to right sides.

Good luck.

What is the resistance of the ride height sensor when you make the adjustment to get 2.8 volts?

 

[c aphook48]

I have a 2006 Lincoln town car that I replaced the air springs with coil springs. The check air suspension lights up on my dash. I believe that the car is riding high and the level sensor is relaying that information. Will adjusting the level sensor stop this from occurring?

______________________________

 

[dave42]

I have a 2006 Lincoln town car that I replaced the air springs with coil springs. The check air suspension lights up on my dash. I believe that the car is riding high and the level sensor is relaying that information. Will adjusting the level sensor stop this from occurring?

Well, no. If you turn off the switch in the trunk, that dash message will always be on. Now, at least a few folks converting to coils have commented on leaving the switch on, leaving the electrical connections to the solenoids intact (move the solenoids out of the way), and adjusting the height sensor and then securing it in place to read the correct height, and that "fools" the car into thinking the air springs are hooked up and the car at the correct height, so no message and the compressor never comes on. On mine, I just ignore the message.

 

[c aphook48]

Well, no. If you turn off the switch in the trunk, that dash message will always be on. Now, at least a few folks converting to coils have commented on leaving the switch on, leaving the electrical connections to the solenoids intact (move the solenoids out of the way), and adjusting the height sensor and then securing it in place to read the correct height, and that "fools" the car into thinking the air springs are hooked up and the car at the correct height, so no message and the compressor never comes on. On mine, I just ignore the message.

Thanks for replying. Yes, I have left the solenoids in place and bagged them. I have the switch turned on and just want to adjust the level sensor to fool the computer. I understand that the output voltage out of the sensor should be 2.80 volts. Is there a way to measure it without having the Ford scan tool?

 

[dave42]

I've never tried, but a voltmeter?

 

[wolf_walker]

Yeah check voltage with meter at the sensor, only a couple of wires, I think it's a 5 volt signal it outputs to the computer.

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[Koach]

Thanks to this forum I was able to make a minor adjustment that turned out perfect. Loosened the two nuts, moved toward drivers side 1/8", and drove home to find it perfectly acceptable.
Measurements before measured at the little concave seam of the lower trim panel; front 13.75", rear 15.125". So almost 1.5" difference. I haven't measured since and don't know that i need to as it looks perfectly level. I probably will for gee whiz...after I'm done fixing the saturated carpet leaks on both sides...ugh!

 

[Racer2012]

What part of this procedure applies to adjustment, r&r and specs with some crazy computer commands. is it adjustable or not appears not to be

I'm getting a C1818 code after driving for about 1/2 hour, But will go out after the ignition is turned off and back on after driving another 1/2 hour .. I'm at 27'' wheel lip to ground on both sides and it seems a little stiff and the system doesn't bleed down with the switch off sitting over night .. For the code it says ck the height sensor .. Do you need the NGS to set the ride height ? Or is there another way ? It's an 02 Towncar and looking at it on the ground I didn't see clearly any way to adjust it .. Or any other ideas on where to look

 

[tadams]

The height sensor for the 1998-2002 models seems to be unobtainium, at this time.

 

[tadams]

1998 to 2002 Town Car air suspension height sensor adjustment

The 1998 and up to 2002 Town Cars use a straight height sensor. .......

.......Adjust the position of the ride height sensor according to the attached ride height adjustment document. The rear suspension ride height is given in the attached specs document. It is 5" plus or minus 0.3". ........

Town (and any others) with a potentially failed height sensor on a 1998 model, is there any reason to think that the later model height sensor can't be adapted, instead? Is the electrical plug similar? Will the voltage reading be identical? (Etc)

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[oktowncar]

Town (and any others) with a potentially failed height sensor on a 1998 model, is there any reason to think that the later model height sensor can't be adapted, instead? Is the electrical plug similar? Will the voltage reading be identical? (Etc)

I don't see why it wouldn't work. You may have to adjust the watts linkage. The sensor is basically an on/off switch

 

[Norms1stTC]

The height sensor for the 1998-2002 models seems to be unobtainium, at this time.

Yes, you'll need to visit a salvage yard

 

[Henrik]

I don't see why it wouldn't work. You may have to adjust the watts linkage. The sensor is basically an on/off switch

I've been thinking same too many times, it's only a switch...
Some day will try to find out what information the sensor actually sends... I believe with some kind of potentiometer or resistor combination, you can fool the computer. Height adjustment is easy, only new wiring for solenoids and compressor, but how I do it without the "air suspension" light on the dashboard thats the trick...

 

[tadams]

I've been thinking same too many times, it's only a switch...
Some day will try to find out what information the sensor actually sends... but how I do it without the "air suspension" light on the dashboard thats the trick...

That's it, exactly. Due to health issues, I haven't been able to get under there and check voltage or impedance numbers. In fact, I'm still just rolling with the bad height sensor and the light on the dash - raising the car to where I need it, manually, and deflating when necessary by the procedure in the factory repair manual.