1995 Blazer 4.3L Engine P0600 and P0340 Code Diagnosis Guide
I'm looking for help diagnosing two trouble codes on my 1995 Blazer with a 4.3L engine: P0600 (Serial Communication Link Fault) and P0340 (Camshaft Position Sensor Circuit). These codes are appearing together, which suggests a potential issue in the wiring or sensor circuit between the camshaft position sensor (CMP) and the Engine Control Module (ECM). Given that both codes point to communication issues, it's likely the problem lies in the wiring harness connecting the CMP sensor to the ECM. To troubleshoot: - Check continuity between the CMP sensor’s brown/white wire and pin 3 on the blue connector at the ECM. - Verify continuity between the CMP sensor’s pink/black wire and pin 8 on the same blue ECM connector. - Ensure there is proper voltage (12 volts) between the CMP ground wire (pink) and the battery negative terminal. Note: These tests must be performed carefully. Shorting any wires during testing can cause a voltage spike that may damage the ECM. Always disconnect power before working on wiring connections.
Since you're receiving both a P0340 (Camshaft Position Sensor Circuit) and P0600 (Serial Communication Link) code, the issue is likely in the wiring between the camshaft position sensor (CMP) and the Engine Control Module (ECM). Assuming your 1995 Blazer has the later model with a 4-pin ECM, perform these checks: - Test continuity from the CMP sensor’s brown/white wire to pin 3 on the blue connector at the ECM. - Check continuity from the CMP pink/black wire to pin 8 on the same blue ECM connector. - Confirm that there is 12 volts between the CMP ground wire (pink) and the battery negative terminal. Caution: Always avoid shorting any wires during testing. A short circuit can send a voltage spike into the ECM, potentially damaging it.