There is nothing you can "unplug" to turn off the "Service Suspension" msg/code. Removing/disconnecting fuses, modules, sensors, or components Will trigger the msg.
When you start your truck, the BCM looks for info from: electronic shocks, height-sensors, and the compressor. If the BCM does not see the expected values, fault code(s) and "Service Suspension" msg will be generated.
Unless you are certain of the cause for the msg, like deleting electronic shocks, you should use a scan tool to diagnose the fault. There are many inexpensive scan-tools available that will diagnose suspension system codes. Most will also let you "command" certain air suspension functions to assist in trouble-shooting. If you want to "recalibrate" the air-suspension levelling system, only a GM Tech2 can do that.
If you connect a scan tool, and it fails to connect with the suspension module, it is likely at least one of your problems. The module is located under your truck above the spare tire. If you live in an area with salty winter roads, the module is probably rotten. New modules are available, pricey, and must be programmed at the dealer. Decent sed modules are available for a better price from reputable auto wreckers (in dry states) and usually don't need programming. If you buy a used one, make sure it comes with the mounting bracket (it is riveted to the module).
- If you are just replacing the shocks with the non-electronic type, installing resistors at each shock position will prevent codes/msgs.
- If you are deleting the air suspension: Leave the lever-type height sensors alone, as the BCM checks them on start-up. If you remove the compressor, the BCM will be looking for signal from the exhaust valve solenoid, and the pressure sensor. You can handle this by using the wiring harness/plug from the old compressor, with the pressure sensor, and exhaust valve solenoid (or similar device) wired in. Just weather-proof it , and mount it above the frame.
