Got code P0688 (engine control module/ powertrain control module power relay sense ciruit /open) does anyone know what this mean or where the engine control module relay is?

 

According to Ross-Tech, Start Here....

17072/P0688/001672 - ECM Power Relay Load Circuit: (J271): Open Circuit

Possible Symptoms
Engine Coolant Fan running at full Speed while Ignition is OFF and Engine is COLD (could lead to discharged Battery)
Possible Causes
Fuse(s) faulty
Power Supply Relay for Engine Control Module (J271) faulty
Terminal 87 faulty/hanging
Wiring between Engine Control Module (J220) and Power Supply Relay for Engine Control Module (J271) faulty
Possible Solutions
Check/Replace Power Supply Relay for Engine Control Module (J271)
Check Wiring between Engine Control Module (J220) and Power Supply Relay for Engine Control Module (J271)
Check/Replace Engine Control Module (J220)

 

in the engine compartment,if left hand drive the E-box fuse and relay box is on the right side corner near the windshield.