2009 Suzuki 400 LTZ Quad Sport Service Manual, Page 109Get this manual
1A-45 Engine General Information and Diagnosis: Step Action 1) Turn the ignition switch OFF2) Connect the ECM coupler and IAP sensor coupler3) Insert the needle pointed probes to the lead wire coupler4) Run the engine at idle speed and measure the IAP sensor output voltage at the wire side coupler between GB wire and BBr wireSpecial tool (A): 0990025008 (Multi-circuit tester set) (B): 0990025009 (Needle pointed probe set) Tester knob indication Voltage) IAP sensor output voltage Approx1.7 at idle speed ((+) terminal: GB () terminal: BBr) Yes Go to Step 4No Check the vacuum hose for crack or damage Open or short circuit in the GB wire If vacuum hose and wire is OK, replace the IAP sensor with new oneRefer to "IAP Sensor Removal and Installation in Section 1C (Page 1C-2)" (A)