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2002 TC Intermittent Air Suspension Light on

Retir3d

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Thread starter #21
I will jumper the air suspension switch in the trunk & test it.

The reason I was trying to locate that connector C457 is that 4 years ago the car suffered the infamous water leak around the ventilation air intake and the carpet in the passenger side front and back got pretty wet a couple of times. If the connector is in that area it may be corroded.

Edit I was typing as you were attaching. I see C457 now.

Thanks again.
 
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Retir3d

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Thread starter #22
An alternative would be to power pin 2 on the module from pin 22 on the module with a jumper since that would maintain correct voltage (that may not be 12 volts)

I've been pretty busy this morning checking stuff. After removing power from the Air Suspension system I removed the glove box and using a razor blade removed a tiny bit of insulation from the yellow suspension enable wire going to pin 2 on the module and did the same for the violet / orange tracer wire going to the power output on pin 22 of the module. I jumpered them together with a small alligator clip jumper wire insuring I had a good connection. After reinstalling the 10A and 30A fuses I took it for a test drive. Sadly, after ~7 miles the "Air Suspension" light was illuminated again. This is the same symptom I've had all along.

I taped over the removed insulation mentioned above. I removed power from the module and went ahead and checked everything I could think of very carefully from the module connectors using a long 10 gauge copper stranded jumper wire. I checked all 4 wires going to the ride height sensor for continuity and any shorting to ground. While checking continuity, I flexed the wire in the area inboard of the sensor connector where the wire was not supported well. I also checked the coil resistance of the air spring solenoids. They both read about 20 ohms, which I expect is normal. I could find nothing that was suspect in all the above.

I'll share a little background on the car as it may bring on some new ideas. I bought the car from a close friend 6 years ago and it is about as pristine an example as I have ever seen. It has never been wrecked and the first 10 years it was garaged. It stays outside now and doesn't see a lot of use. I live in the southeast US and the car has never been exposed to salt. I have checked for visible rodent damage to the wiring, but have seen nothing.

Thanks again for your help!
 
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Town

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Ottawa Ontario Canada
#23
Perhaps a recap would help:
- problem starts with the suspension light coming on after a few minutes of a drive, every drive. Timing varies.
- On checking the compressor seems fine since it inflates the air springs in a short time.
- on checking further the drier is soaking wet and the vent solenoid is completely corroded.
- replace compressor and drier and vent solenoid as a complete unit and it works but takes longer to inflate air springs.
- air springs maintain a visually level and good ride height.
- air springs vent overnight by 5/8" and with new compressor take 3 mins to achieve level trim height (about 3 mins is max continuous run time on compressor before safety switch shuts it down.
- Suspension height sensor is oriented correctly and maintains ride height but does not cause venting when car lifted.
- used height sensor replaces original and works for all 3 trim levels: venting, level and raising.
- used 1998 suspension/steering module works as well as original module but does not change the light in message center from coming on.
- bypassed suspension off switch at module and the message light still lights after a while of driving.,
- carious connections and wires tested for height sensor and trunk switch and module but no problems found.

Things that may not have been checked:
- It is anticipated that the power connection at the module pin 22 is powered and powers pin 2 from the trunk off switch and jumper, but is that circuit powered when car is driving?
- power to the module is on pin 16 from fuse 8 (10A) in CJB in passenger compartment, so could there be an open in that circuit (wh/vt) if there is no power at pin 22 when driving.
- power to the module on pin 1 from BJB in engine compartment fuse 17 (10A) DG/Ye or an open while driving?
- Compressor is powered by BJB fuse 12 (30A) which seems to be working correctly, but the vent solenoid is powered by module pin 24 pink wire.
- there are pins 9 and 10 that receive network data: vehicle speed, odometer info, driver door and pasengers door ajar status. So perhaps an issue there since the problem is when car is moving?

You could copy and paste any corrections to the above and we could see a full list of what is happening. Might be helpful.
 

Retir3d

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Thread starter #24
I made the correction and additions in red

Perhaps a recap would help:
- problem starts with the suspension light coming on after a few minutes of a drive, every drive. Timing varies. I would add that during a recent 1400 mile long trip to the mountains heavily loaded in trunk with 3 passengers it would usually only come on once or twice a day The back did not appear to sag whether the light was on or off.
- On checking the compressor seems fine since it inflates the air springs in a short time.
- on checking further the drier is soaking wet and the vent solenoid is completely corroded.
- replace compressor and drier and vent solenoid as a complete unit and it works but takes longer to inflate air springs.
- air springs maintain a visually level and good ride height.
- air springs vent overnight by 5/8" and with new compressor take 3 mins to achieve level trim height (about 3 mins is max continuous run time on compressor before safety switch shuts it down.
- Suspension height sensor is oriented correctly and maintains ride height but does not cause venting when car lifted until door is opened.
- used height sensor replaces original and works for all 3 trim levels: venting, level and raising.
- used 1998 suspension/steering module works as well as original module but does not change the light in message center from coming on. It was same p/n as original
- bypassed suspension off switch at module and the message light still lights after a while of driving.,
- carious connections and wires tested for height sensor and trunk switch and module but no problems found. I also checked the entire air system run including the air springs, solenoids, and tee and tubing run with soapy water and found no leaks

I will try to work out a way to test your suggestions while driving.

Thanks again & stay tuned
______________________________
 

Town

Senior Member
3,814
41
48
Ottawa Ontario Canada
#25
I was looking for more info on the data transmitted to the module while driving. The only data that would set a DTC in the module is the vehicle speed which is provided by the ABS module. Have you had any speedometer issues or an occasional ABS light? Something intermittent that may coincide with the air suspension light?
 

Retir3d

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Thread starter #26
I was looking for more info on the data transmitted to the module while driving. The only data that would set a DTC in the module is the vehicle speed which is provided by the ABS module. Have you had any speedometer issues or an occasional ABS light? Something intermittent that may coincide with the air suspension light?
Thanks for the further research. The speedometer seems to work perfectly and the only time I ever see the ABS light is during the Instrument panel power on self test when you first tun the key to "on". It goes away as expected. I have been watching the odometer carefully today and found the "Air Suspension" light is coming on after almost exactly 7 miles of driving. I noted the compressor running for 10 seconds prior to it coming on, but that may have been due to an incline when I was turning around. I put a couple of new 10A fuses in the power feeds to the module for good measure. Made no difference. I'm about to make some of the suggested checks from yesterday.
Thanks again and stay tuned.
 

Retir3d

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Thread starter #27
- It is anticipated that the power connection at the module pin 22 is powered and powers pin 2 from the trunk off switch and jumper, but is that circuit powered when car is driving?
Yes

I connected my DVOM to the yellow wire on pin 2 of the module and a frame ground and went for a ride with my wife monitoring the meter. Voltage ranged from 10.8 to 11.3 and suprisingly we made 18 miles before the "Air Suspension" light illuminated. The voltage measured remained constant after the light illuminated.

I switched of the car and the meter restarted it. After 7 more miles the light came on again. My DVOM is a cheap Harbor Freight item and I don't know the internal impedance, but am wondering if the load of the meter on the circuit may explain the longer wait until the light coming on? I know the ground going to pin 6 is good, but wonder if maybe the connection to pin 6 has issues. I'm going to take a closer look.
 

Retir3d

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Thread starter #28
Success!

<cautiously optimistic>

I dismantled one of the two connectors to the control module C250 and removed the socket that pin 6 connects to. A careful inspection revealed a waxy substance coating the inside of the socket. More inspection found this substance in all the sockets of C250 and C251. Using a tiny nylon brush made for cleaning between teeth and a half can of contact cleaner I removed the waxy material from both the sockets and the pins coming from the air suspension control module.

I drove ~40 miles nonstop with no warning light. I will feel better after a longer trip is taken, but this is the first positive change seen since starting to work on the problem.

My suspicion is that this waxy material was blocking the low power signals carrying the network data.

- there are pins 9 and 10 that receive network data: vehicle speed, odometer info, driver door and pasengers door ajar status. So perhaps an issue there since the problem is when car is moving?
Many thanks to you, Town, for helping me work through this very annoying issue!!!

Best Wishes
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