[Jim-lahey]

Just bought a 2004 deville dts, great car, but I noticed today the drivers side rear wheel is tucked under the fender, where as the other 3 tires there is about 2 - 3 inches of space between the tire and fender. The air pump runs for a minute or 2 on every start up and I don't hear an air leak. Hooked my code reader up to the obd2 port, there are no codes at all. There is a message that pops up on starting the car about tire pressure, could that be related in any way? Any help would be appreciated, it's my first caddy, I've been working on vehicles for a long time, but mostly engine/transmission work.

2004 deville dts
252,000 kms
Stock tire size - filled to proper psi

 

[Submariner409]

""2004 DTS" tells us everything we need to know about the vehicle.

ELC (Electronic Level Control) should do a 2 second preload/proveout about 6 seconds after Key: ON. The rear should be level side-to-side with maybe the slightest hint of forward rake. If there is a slow leak (soap bubble spray test of air lines and shock bladders) then the system will take a few seconds to level the car after each Key: ON.

Your car has its own built-in diagnostic code system/scanner/memory/readout. Codes read out in the message area as a letter, four digits, a letter. Learn the system by studying the correct model/year section of the sticky thread up there ^ ^ ^, marked with a push pin, "How to pull codes". You can either auto-scroll each system/module or leaf through them one at a time. Here's the DIC control buttons and a link to code definitions.

How To Pull Codes (DTC's)

To check for Diagnostic Trouble Codes stored in the computer, turn the ignition on, then hold down the OFF and WARMER (for digital dash) or OFF and passenger-WARMER buttons (for analog dash) or OFF and "Info ^" buttons (if you have temperature dials) until all of the dash lights come on. The...

www.cadillacforums.com

OBDII diagnostics. Trouble codes description for GM

OBDII/EOBD diagnostic code definition. More than 18000 codes for all autos. Trouble codes description for GM

obdii.pro

 

[Jim-lahey]

Thanks for the quick reply man. I checked for codes as how you mentioned above, the only current code is for the rear passengers climate control.

The rear drivers side doesn't come up to proper height or even move one bit while the ELC is cycling. I will try to lift the car so I can check for a leak in the air lines as you mentioned above. I did put my head under while it cycled and didn't hear an audible leak, but I guess it probably wouldn't be loud enough anyway.

 

[Submariner409]

The springs actually control ride height - the ELC maintains rear height/level in response to changes in weight in the trunk or rear seat. If one side is noticeably "tilted" then you have spring or suspension mount/control arm problems, too.

ELC acts on both shocks equally - one air supply/vent line with a T to both shocks.

 

[Jim-lahey]

Oh OK, this system is making sense to me now. Checked the springs, and the problem sides spring is definitely more compressed (obviously lol) than the other side, but didn't feel or see any cracks or signs of damage. I don't know if maybe they just lose stiffness/height over time? I'm really hoping it isn't a control arm problem

 

[Submariner409]

You would be nowhere near the first to have one or both sagged rear springs on a Deville.

Replacing springs is not rocket science and is fairly inexpensive. BASSCATT will know the best brands to use. Your DTS uses the "performance suspension" FE3 package so the spring are different - much different - from the base or DHS trim levels. Get the correct springs. Make sure the ELC system is tight and functioning correctly while you're (or mechanic) in there.

I notice that there's a FE7 package for "heavy duty" in 2004 model year. Make sure to double check correct spring usage.

 

[Jim-lahey]

Ok awesome that doesn't sound too bad at all. Thanks for all the help/great info man!

 

[Submariner409]

For you or the mechanic - here's a diagram of the ELC compressor and air line setup. It's for my 2002 Seville but is typical of the 1998 - 2005 models.