P0688 Toyota Electronic Control Module Power Relay Control Circuit Open
Possible causes
– Weak battery- Low voltage while cranking
– Faulty Engine Control Module (ECM) relay
– Blown ECM fuse
– Faulty ECM
– ECM harness is open or shorted
– ECM circuit poor electrical connection
– Faulty Engine Control Module (ECM) relay
– Blown ECM fuse
– Faulty ECM
– ECM harness is open or shorted
– ECM circuit poor electrical connection
Tech description
Check all the ECM fuses, if the fuses are OK try replacing the ECM relay.
Symptoms
– Engine Light ON (or Service Engine Soon Warning Light)
Toyota Vehicle:Toyota Prius,Toyota Celica,Toyota Supra,Toyota Carina,Toyota Camry,Toyota MR2,Toyota Aygo,Toyota 4Runner,Toyota Avalon,Toyota Camry,Toyota Corolla,Toyota FJ Cruiser,Toyota Highlander,Toyota Land Cruiser,Toyota Matrix,Toyota Prius,Toyota RAV4,Toyota Sequoia,Toyota Sienna,Toyota Solara,Toyota Tacoma,Toyota Tundra,Toyota Yaris,