Crankshaft Position Sensor
The PCM uses the Crankshaft Position (CKP) sensor to detect crankshaft speed and position. The CKP sensor is located behind the harmonic balancer. See Fig 1. The CKP sensor connects to the PCM through the 12-volt reference circuit, the low reference circuit and CKP sensor 1 signal circuit. If PCM detects that the CKP sensor signal is incorrect for 3 seconds, a DTC will set. To diagnose, see SELF-DIAGNOSTICS - 4.3L ASTRO, BLAZER, JIMMY CANADIAN, SAFARI, SONOMA & S10 PICKUP article.