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Help! Ridin" high!


sprucegoose

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I replaced the rear shocks on my '98 Eldorado with a new set or Arnott shocks a couple weeks back. Don't drive the car much, but when I do each time I use it the rear ride height gets higher! I disconnected the line once and let all the air out. Then I disconnected the battery with hopes that rebooting the brains of the body controller would help... No such luck.

With the old tired out OEM shocks it was actually sagging 1" or so too low. Now it is pumped up like 2-3" too high! Any suggestions on why this is happening or how to test or adjust the ride height control switch back there? Any help or prior experience with this would be great! Hasn't thrown any DTC codes to give me any clues either...

'09 Cadillac CTS-4 3.6 direct injection, 128 K mi.
'15 Chevy Tahoe LTZ, 5.3i V8, 125 K mi
'70 Firebird Formula 400, Bored+.04, RAIII heads, M21 4spd., in-process restoration!

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You should check your OBD codes and post them here. The codes will likely tell the tale. Without the codes or looking at the car I can only guess, but two things come to mind: a stuck exhaust solenoid and bent or loose suspension height sensors.

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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Thats the thing Jim, there were no codes related to suspension! Just other things like low A/C refirgerant etc. that I already new about. I'll check again tonight but I have not seen anything come up on my display at all since I cleared them...

I'm thinking it is the exhaust valve for the compressor as it seems to obviously pump up just fine and the sensor on the suspesion appears to all be intact and functional (mechanically anyway) Is that adjustable at all? I should figure out how to trouble shoot the electronics there too of course...

'09 Cadillac CTS-4 3.6 direct injection, 128 K mi.
'15 Chevy Tahoe LTZ, 5.3i V8, 125 K mi
'70 Firebird Formula 400, Bored+.04, RAIII heads, M21 4spd., in-process restoration!

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If you don't have an S037 or S038 the PZM thinks the exhaust solenoid is OK but that doesn't mean that it isn't sticking. Turn the key on in a quiet garage, and you should be able to hear the compressor run for a few seconds. The fuel pump will be a more subdued vibration that goes on for about 10 seconds. If so, then just that will eventually pump up the rear if the exhaust valve is stuck closed.

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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You already know how to release the air, so get it to proper hieght and pull the ELC fuse out then when it feels like it needs more air put the fuse back in and pull it. I did that with my Eldo when it started to look like a 70's race car and never bothered to fix it because it was very rare that it needed air.

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The linkage arm might have an adjustment on it, but I'm not sure. To check it, crawl under the car and disconnect the linkage arm. Moving it one way should activate the compressor and moving it the other should activate the exhaust valve. If it doesn't, you've found the problem.

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You have to be careful when moving the linkage rod though as I do believe that it will trip a code if you go out of the sensors limits, basically one side will exceed the allowable limits compared to the other side.

I would definately second the exhaust valve is bad. They corrode interally in the pumpand if you pull the pump assembly and remove the exhaust hose you will likely see that the hole is oxidized shut completely.

You can also do a suspension check through your DIC under RSS override that will cycle the compressor and exhaust which will raise and lower the vehicle slightly while in the test mode.

Basically 3 seconds the motor runs then 3 second the exhaust valve openss, Repeat, etc...

That is how I test the system for proper function

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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could you possibly post a pic of your curreny ride height

Sorry for the delayed respose, been out of town for a few days... Here's a couple pics when she's jacked up!

ELC_side.JPG

ELC_rear.JPG

'09 Cadillac CTS-4 3.6 direct injection, 128 K mi.
'15 Chevy Tahoe LTZ, 5.3i V8, 125 K mi
'70 Firebird Formula 400, Bored+.04, RAIII heads, M21 4spd., in-process restoration!

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If you don't have an S037 or S038 the PZM thinks the exhaust solenoid is OK but that doesn't mean that it isn't sticking. Turn the key on in a quiet garage, and you should be able to hear the compressor run for a few seconds. The fuel pump will be a more subdued vibration that goes on for about 10 seconds. If so, then just that will eventually pump up the rear if the exhaust valve is stuck closed.

Yes, I definitely hear the compressor run when the key is turned on and this is what is eventually pumping it way up.

You already know how to release the air, so get it to proper hieght and pull the ELC fuse out then when it feels like it needs more air put the fuse back in and pull it. I did that with my Eldo when it started to look like a 70's race car and never bothered to fix it because it was very rare that it needed air.

Thanks Pete I did this tonight to at least control the ride height till I find the problem!

The linkage arm might have an adjustment on it, but I'm not sure. To check it, crawl under the car and disconnect the linkage arm. Moving it one way should activate the compressor and moving it the other should activate the exhaust valve. If it doesn't, you've found the problem.

Yes, I found the adjustment. It is a 10mm hex-head bolt in the middle of that switch rod. When I loosened it and moved it up or down it didn't make a difference. The pump didn't kick on and the exhaust valve never opened.

You have to be careful when moving the linkage rod though as I do believe that it will trip a code if you go out of the sensors limits, basically one side will exceed the allowable limits compared to the other side.

I would definately second the exhaust valve is bad. They corrode interally in the pump and if you pull the pump assembly and remove the exhaust hose you will likely see that the hole is oxidized shut completely.

You can also do a suspension check through your DIC under RSS override that will cycle the compressor and exhaust which will raise and lower the vehicle slightly while in the test mode.

Basically 3 seconds the motor runs then 3 second the exhaust valve openss, Repeat, etc...

That is how I test the system for proper function

Yes, doing this test above did cause two codes... DTC P1575 Extended travel brake switch curcuit and DTC C1297 PCM Indicated Brake Extended Travel Switch Failure

I think the first thing I need to do is pull that pump. No time tonight. Looks like a PIA to get at though...

'09 Cadillac CTS-4 3.6 direct injection, 128 K mi.
'15 Chevy Tahoe LTZ, 5.3i V8, 125 K mi
'70 Firebird Formula 400, Bored+.04, RAIII heads, M21 4spd., in-process restoration!

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Yes, I found the adjustment. It is a 10mm hex-head bolt in the middle of that switch rod. When I loosened it and moved it up or down it didn't make a difference. The pump didn't kick on and the exhaust valve never opened.

I assume you did this with the engine running?

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Yes it is a PITA to pull the pump, but is definately doable.

I have pulled andd installed 6.

3 most common problems I see, (When I say common I mean all 6)

the exhaust hole corroded shut

the hose deteriorated off the pump for the exhaust

and water in the pump because of the lack of the drain.

I pull the entire bracket with the compressor so that I dont have to fight with the bolts and bushings to the compressor., Once I have the unit on the table I remove the compressor.

There are 4 bolts holding the bracket under the car, 3 are easy to see and to get to and one is not, It looks hidden but it is directly above the suspension. You will have to turn the pump it different positios to remove and install it, so be patient and it will come out.

My best advice is unplug the plugs and hoses once you unboly the compressor as they are more accessable.

And that is the highest eldorado I have ever seen, lol. Good luck. It will definately pay off if done correctly.

If replacing pump with a used unit, the oldsmobile aurora can work with modifications but is not recommended

GM FAN FOREVER

Nice, clean, luxury= fine automobile

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Yes, I found the adjustment. It is a 10mm hex-head bolt in the middle of that switch rod. When I loosened it and moved it up or down it didn't make a difference. The pump didn't kick on and the exhaust valve never opened.

I assume you did this with the engine running?

You know, I am pretty sure it wasn't running... just had the key in the "ON" position thinking that was the same. I think I may try it again, as it way be the switch but I'll bet it is the exhaust port on the pump by the way rockfangd is describing it.

'09 Cadillac CTS-4 3.6 direct injection, 128 K mi.
'15 Chevy Tahoe LTZ, 5.3i V8, 125 K mi
'70 Firebird Formula 400, Bored+.04, RAIII heads, M21 4spd., in-process restoration!

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I can't help but wonder what told the compressor to run to raise the rear end of the car that high in the first place.

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

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I can't help but wonder what told the compressor to run to raise the rear end of the car that high in the first place.

Well, as Jim said in post #5 the compressor cycles every time you start the car (or turn the key forward). It is only for a few seconds, but it raises the rear by about 1/4" or so every time here from what I was seeing. I'm sure it is supposed to bleed that air off every time also though to set the ride height, but if the exhaust port is plugged or non-functioanl it can't. So my theory is that it just keeps accumulating the height gradually because of this.

'09 Cadillac CTS-4 3.6 direct injection, 128 K mi.
'15 Chevy Tahoe LTZ, 5.3i V8, 125 K mi
'70 Firebird Formula 400, Bored+.04, RAIII heads, M21 4spd., in-process restoration!

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I think that when it runs for a few seconds when the key is turned on and the exhaust valve is clogged, then, over time, the rear end gradually jacks up.

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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