2009 Suzuki 400 LTZ Quad Sport Service Manual, Page 101Get this manual
1A-37 Engine General Information and Diagnosis: P0115-L (Use of SDS) Step Action 1) Turn the ignition switch OFF2) Check the ECT sensor coupler for loose or poor contactsIf OK, then check the ECT sensor lead wire continuityYes Go to Step 2No BBl wire shorted to ground If wire is OK, go to Step 2 I933H1110039-01
3) Disconnect the ECT sensor coupler4) Check the continuity between BBl wire and groundIf sound is not heard from the tester, the circuit condition is OKSpecial tool (A): 0990025008 (Multi-circuit tester set) (B): 0990025009 (Needle pointed probe set) Tester knob indication Continuity test)