Electronic level control

[desi123]

Hi all. I have a 1978 Cadillac Coupe DeVille that i’d like to install the original elc system in. I was wondering what part numbers I’d need to do a full install. I’ve found an original nos compressor for that year and ac delco makes a shock kit
504-511 can I put the nos compressor together with that ac delco part number? Besides those components what else would I need? Thanks

- Desmond

[TJ Hopland]

Your car never had it?   Or did it have it but most of the parts have been removed?

78 was around the time they went to electric compressor vs the vacuum powered ones?  I assume you are looking at electric?

The last major component you are missing is the level sensor.  The electric version the sensor and 'brains' were all in one module.  It had an arm on it with a carburetor like linkage to the axle.   Depending on the position it would either signal a relay up front to operate the compressor or directly signal the bleed valve on the compressor assembly to bleed air off.   The module is where the timing and buffering logic is to keep it from trying to make adjustments from transients like going over bumps.

Those modules seemed to be the weak point and what usually failed besides the shocks themselves from just age and miles.   I don't think aftermarket ever made the modules and I never remember hearing about anyone repairing them.   I don't know if they actually had electrical failures or just got wet or contaminated with road grime.         

[desi123]

No the car never had it as far as I know and yes the electric system not vacuum. Do you have part numbers for the parts I’d need ie; relays, lights, module, wiring, sensors etc...    Thanks
Oh and would that acdelco 504-511 work with the original compressor?

[35-709]

IMO, you are adding what, over time, became a troublesome feature that many would rather be without. 

[78Elegante]

Desmond,
Assuming the system you want to build is (very close to) the same as what cam standard on the '76-'79 Seville, for the wiring you can look at my website:
http://www.cadillacseville.org/elctroubleshoot78.html#27

As you can see, from wiring point of view it is a pretty simple system.

As for the part number question, I cannot answer. But when you search for 'ELC sensor' you will find some comparable items.
To be honest, I do not understand why there are so many different height sensors. Basically they only measure an angle and based on too big or too, they ground one wire to either activate the compressor through the relay to increase the height of the car or the vent solenoid to decrease the height of the car.

[TJ Hopland]

The trick to the electric sensors is they have some circuitry in them to buffer the signals so it doesn't react every time you go over a bump.  I don't know if they were maybe changing the timing or the design of the circuit or maybe just trying to make it more weather proof?   Analog timing circuits often don't age well. 

Its been many years since I searched but I do recall that the few times I was looking for one it was the sort of thing where if you did find one they were often asking $100's of them and the warranty was 'ran when parked'.  I also remember seeing listings for ones that supposedly fit many models and years when I knew that wasn't true so another thing that made the risk pretty high to buy one.