ID14 Checking Wiring Harness (Circuit 175)
^ Using a voltmeter, connect positive lead to Circuit 175 of air compressor relay's wiring harness connector and the negative lead to Circuit 430B.
^ Is voltage reading greater than 10 volts?
YES -- GO to ID15.
NO -- SERVICE open or short in circuit. There should always be battery voltage on this circuit REPEAT Service Bay Diagnostics. Reading and Clearing Diagnostic Trouble Codes