Knock Sensor: Miata
- Resistance Inspection
Disconnect Knock Sensor (KS) 2-pin harness connector. See Fig 1. Using DVOM, measure resistance between KS terminal "A" and KS body. Resistance reading should be about 560,000 ohms at 68°F (20°C). If resistance reading is not as specified, replace KS. If KS resistance reading is within specification, check for open or short circuit in wiring harness. Go to next step.
- Open Circuit Inspection
Disconnect PCM 31-pin harness connector. Check for continuity between KS harness connector terminal "A" (White wire) and PCM 31-pin harness connector terminal No. 4M through common connector. If continuity is present, go to next step. If continuity is not present, repair open circuit in White wire between KS harness connector and PCM 31-pin harness connector terminal No. 4M or replace wire harness. See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS.
- Short Circuit Inspection
Check for continuity to ground between KS harness connector terminal "A" (White wire) and PCM 31-pin harness connector terminal No. 4M. If continuity is present, repair short circuit to ground in White wire between KS harness connector terminal "A" and PCM 31-pin harness connector terminal No. 4M or replace wire harness.
Courtesy of MAZDA MOTORS CORP.