Code 3-1-2 (Knock/Fuel Enrichment Signal Missing)

Turn ignition on. Connect a voltmeter between terminal No. 28 (Brown/White wire on 240 Series; Gray/Red wire on all others) of fuel system ECU connector and ground. Reading should be approximately 0.7 volt. If voltage is not specified, check resistance between appropriate ECU connector wire and knock sensor. For knock sensor testing, see SYSTEM/COMPONENT TESTS article in the ENGINE PERFORMANCE Section.