Possible causes

– Faulty Engine Control Module (ECM) power relay
– ECM power relay harness is open or shorted
– ECM power relay circuit poor electrical connection
– Faulty (ECM)

Tech notes

Check all the ECM fuses, if the fuses are OK try replacing the ASD relay.

Symptoms

– Engine Light ON (or Service Engine Soon Warning Light)

P0685 JEEP Description

Short or open in Auto Shutdown (ASD) relay circuit