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my eldo is riding high.


rockfangd

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Hi all. My eldo is at it again. 2001. Eldorado ESC

I have never had a car do this before, and I have had enough of them...

the back end is high, the edge of the wheelwell to the top of the tire on each side is about 4".

It seems to be riding harsher than normal, And feels unsafe on the roads when roads are snow covered, etc...

I am assuming the exhaust valve is stuck but am not sure. I cannot find RSS in the onboard system so I have no idea what actually controls the system. On my other caddys they have RSS and have the sensored struts. This one does not.

I replaced the 3 vent hoses before winter and ensured the holes were open into the pump and valve. The filter was intact into the unibody last I knew.

I have been so busy I have not had the time to look at it good, and the temps here have been horrible, very cold.

I hope someone has some insight on what I can possibly do to help this one.

I am thinking of bringing the car into shop and putting heater by the car but have no idea if it will help.

I dont want to damage anything by driving the car, but unfortuantely need it more than ever being winter.

thanks all

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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All Eldorados have ride height control in the rear, at least 1992 and later. If RSS is listed in the modules when you run the codes, it was shipped with it, otherwise not. In the 2002 FSM (which should apply to your 2001 Eldorado), the RPO code for RSS is F45 and they call it "Chassis Continuous Valve Real Time Damping."

The troubleshooting guide starts with the symptom check, which starts with a compressor performance test and a system leak test before the chart for "Rear of Vehicle High." I'll mention the things that it says in "Rear of Vehicle High."

The first thing that the chart says to check is the ride height sensors. The next thing is an electrical check of the exhaust solenoid, then short the vent solenoid to ground (with a jumper with a 10 Amp fuse) and see if the exhaust solenoid operates and the system vents air.

The only codes mentioned are C0662/C0663 for the solenoid circuit (with a note "W/F045") and C0657/C0658 for the compressor relay or circuit.

Without F045, there is only one ride height sensor, and it is actually a module, which controls a the ELC relay in rear relay block #2 and the exhaust solenoid. With F045, the CVRSS module does that instead, and two ride height sensors are connected to the CVRSS module.

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-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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Check to see if there are any RSS codes. You might have a height sensor that is malfunctioning.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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Rockfangd said in the first post....

"I cannot find RSS in the onboard system so I have no idea what actually controls the system."

"On my other caddys they have RSS and have the sensored struts."

"This one does not."

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I glanced over that - but there has to be a height sensor. It could be disconnected from the suspension so the compressor keeps running and raising the rear of the car too high.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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Automatic level control W/O F45

Height Sensor Description

The solid-state sensor detects height changes at the rear of the vehicle and, in turn, controls the functions of the compressor and

exhaust solenoid. To prevent energizing the compressor relay or exhaust solenoid during normal ride motions, the sensor circuit provides a fixed delay before ground is completed to either circuit.

In addition, the sensor limits compressor run time and exhaust solenoid energized time to a range of 4.5-7.5

minutes. This prevents continuous compressor operation in case of a severe system leak of continuous exhaust solenoid operation. The timer circuitry is reset whenever the ignition is cycled OFF and ON, or the sensor exhaust or compress output signal changes.

The sensor is mounted to the left front side of the rear suspension support assembly. The actuation arm is

attached to the left rear control arm by a short link.

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I have a component locator also. Pictures with arrows, but I can't seem to copy and past the pics, only the text. any help? they are not actual photos if that matters, they are sketch type.

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See posts #2 and #6 above.


th_2002_ESC_ELC_Schematic.png

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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Ok all. Sorry for the delay. My schedule is a little nuts.

Anyway The link at the height sensor is attached and all looks good everywhere. Link moves freely.

Here is what I did for temporary. I popped the hose off one of the shocks and the car dropped, then I reconnected it.

I cycled the key until the ride height looked normal and pulled the ELC fuse. It rides alot better, a little low now but better.

I think it is the exhaust valve in the compressor because I dont hear it click like normal, and it raises every time I start the car. Do that 10 times and next thing you know car is high.

I will have to check out the compressor when the weather improves. Thanks for the help.

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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Ok does anyone have any idea of what might free up the exhaust valve? I think it is frozen. I have purchased another compressor, known good. but it is just too cold to mess around under the car. I have the car at ride height and the ELC fuse pulled. I would love to think there is a way to get it to work again. I dont want to really change the compressor unless I have to.

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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Ummm, Just to state the obvious, and I mean no disrespect, but when you say frozen, do you mean from the outside cold temps and snow/ice storms we've been hearing about in NY?

We used to be able to use methanol (caution - poisonous) on our over the road trucks to de-ice the air brake system. If you are talking outside low temps and ice, maybe some spray lock deicer or 91% Isopropyl alcohol will do the trick. The hard part would be getting to the frozen exhaust valve. WD40 after the ice is gone.

Never underestimate the amount of a persons greed.

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You need to thaw it out before spraying it with anything. Try a heat gun or if you can leave it in a heated garage overnight, that should work. Then attempt to spray something into the solenoid to keep it from re-freezing.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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Yes it is the outside temps. It feels like alaska with the very cold and swinging temps.

I will try to park it overnight in a heated garage, where do I spray the oil? in the vent holes? I have had a few of these units apart and the valve is in the heart of the unit (basically not serviceable)

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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  • 3 weeks later...

Ok guys. Now that I have my car running again I would like to get the air ride back in order. I have a replacement compressor assembly but would rather not replace it unless I need to.

I would like to know how to manually manipulate the exhaust valve so I can try to get it working again. It may be now but I have had the fuse pulled.

I just reinstalled it today. I would like to pop off the link but dont want to break it. Thanks all

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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The 2002 FSM says that the exhaust solenoid is integral with the compressor head and is not a serviceable part. This means that a dealer tech will, if he follows the FSM, replace the air compressor head.

The FSM says to begin by removing the compressor. If you have a replacement compressor, it would be simpler to just put that in instead of switching the compressor heads.

The air compressor head includes the wiring harness breakout of wires to the motor and the solenoid. the connector wires, are, in order,

  • ORN - circuit 1340 on the schematics: battery voltage from the 30 Amp fuse.
  • DK GRN - circuit 322 on the schematics: compressor motor power.
  • WHT - circuit 320 on the schematics: exhaust solenoid control.
  • BLK - circuit 1050: ground.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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tonight I popped off the link from the height sensor and pushed it down, Nothing happened. I even tried tapping on the compressor around the exhaust valve.

I know that the reaction to the sensor is not immediate so I was patient.

I did notice one thing though, It hits the swaybar when you drop it down, Not sure if this is normal or not.

Going up made the compressor engage after about 15 seconds. So the sensor should be fine.

I guess I will have to swap the compressor unit.

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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  • 2 months later...

Well guys. No luck here.

Weather is warmer and problem is still the same.

Last week I swapped the compressor assembly with a good used one, and it did not help either. 3 days after the compressor was replaced it is jacked right back up and rides hard. Guess I have to look farther into the height sensor at the left wheel and the harness to the compressor.

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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Ok guys here is where I am at with this.

All tests ok except there is no negative output to the white wire at the compressor.

I have no output from the leveling valve at the white wire when putting the arm down.

I have positive activation after about 30 seconds when the arm is pushed up, and the compressor cycles fine.

I manually grounded the white wire to the compressor and verified the exhaust valve is fine, It exhausted.

Basically for anyone who does not know how the system works, here is how it works.

there are 4 wires to the compressor unit.

orange is `12v constant. That is for the exhaust valve.

white is negative activation for the exhaust valve, triggered by the leveling valve.

This is designed so that even when the car is off and the load is removed it will exhaust to normal ride height.

black is constant negative for compressor

dark green is positive activation to compressor, for raising suspension.

The question I have is that when the key is cycled on and the system cycles, does it work through the leveling valve or does it bypass the valve?

I am thinking the leveling valve may be faulty as it has all the inputs but wont output the negative to exhaust. If someone knows of a way (if possible) to bench test the sensor it would be very nice.

thanks all

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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I believe that I have posted this here before:

th_2002_ESC_ELC_Schematic.png

From the schematic, if the WHT wire does not short to ground at the sensor when the rear end is high, the sensor is bad or mounted incorrectly. If it shorts to ground but the solenoid does not exhaust, you have an open WHT wire in the harness. Most likely place for a harness problem is a connector. If the schematic is accurate for your car (and it very likely does apply to the 2001 Eldorado), there are only two connectors, one at the sensor and the other at the compressor/solenoid assembly.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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thank you. that does.

I have no ground output from the white wire at the level sensor when high.

So I am assuming it is the leveling sensor.

It is pricey and not easy to find. I Find the RSS level sensors but nothing like mine

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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You should be able to find a height sensor in a junkyard.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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Ok guys, I could really use some help.

I bombed today at my attempt to get a used sensor. The best yard around had at least 12 different caddys ranging from 1993-2006. Only one had my setup and it was a 94 Deville. All of the other ones had RSS.

Anyway I bought it. The bracket was rotted right off. I will have to try to use my bracket on it.

I am trying to bench test the sensor but No matter what I do I get nothing.

I assumed that the input for the exhaust was the black and the output was the white.

I assumed the input for the compressor was pink/blk, and the output was yellow.

I tried ohming them out while manipulating the rod and got nothing either way.

I am now thinking the unit has to have supply power to work either. I feel stuck .

I will try to install the one I got today and hope it does something useful

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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