Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
1999 Isuzu Rodeo LS 2WD V6-3.2LFACTORY OEM SERVICE PROCEDURE
System Inspection
Knock Sensor (KS) System Check (Engine Knock, Poor Performance, or Poor Economy)
Circuit Description
The knock sensor (KS) sends an AC voltage signal to the powertrain control module (PCM). As the KS detects engine knock, the signal to the PCM changes in amplitude and frequency. The PCM retards timing if the engine speed is over 900 RPM.
Diagnostic Aids
If the KS system checks OK, but detonation is the complaint, refer to Diagnosis, Detonation/Spark Knock. Refer Diagnosis By Symptom.
Test Description
The numbers below refer to the step numbers on the Diagnostic Chart.
9. The change in signal speed depends on how hard the tapping is done. Normally there is about 1.5 to 10 mV at PCM pin A2 with the engine off. Loud tapping should be able to make the reading jump to 20-25 mV AC.
Circuit Description
The knock sensor (KS) sends an AC voltage signal to the powertrain control module (PCM). As the KS detects engine knock, the signal to the PCM changes in amplitude and frequency. The PCM retards timing if the engine speed is over 900 RPM.
Diagnostic Aids
If the KS system checks OK, but detonation is the complaint, refer to Diagnosis, Detonation/Spark Knock. Refer Diagnosis By Symptom.
Steps 1 - 6:
Steps 7 - 10:
Test Description
The numbers below refer to the step numbers on the Diagnostic Chart.
9. The change in signal speed depends on how hard the tapping is done. Normally there is about 1.5 to 10 mV at PCM pin A2 with the engine off. Loud tapping should be able to make the reading jump to 20-25 mV AC.
Factory Service Tools
Use the Manual With the Right Hardware
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.