2010 Cadillac Truck Escalade RWD V8-6.2L Page 1468
DTC Descriptor
DTC P1AC6
- Drive Motor 1 Control Module Crankshaft Position (CKP) Sensor Circuit
DTC P1AC7
- Drive Motor 1 Control Module Crankshaft Position Sensor Performance
Diagnostic Fault Information
Circuit/System Description
The crankshaft position (CKP) sensor circuits consist of an engine control module (ECM) supplied 5-volt reference circuit, low reference circuit
and an output signal circuit. The CKP sensor is an internally magnetic biased digital output integrated circuit sensing device. The sensor detects
magnetic flux changes of the teeth and slots of a 58-tooth reluctor wheel on the crankshaft. Each tooth on the reluctor wheel is spaced at 60-tooth
spacing, with 2 missing teeth for the reference gap. The CKP sensor produces an ON/OFF DC voltage of varying frequency, with 58 output pulses
per crankshaft revolution. The frequency of the CKP sensor output depends on the velocity of the crankshaft. The CKP sensor sends a digital
signal, which represents an image of the crankshaft reluctor wheel, to the ECM as each tooth on the wheel rotates past the CKP sensor. The ECM
uses each CKP signal pulse to determine crankshaft speed and decodes the crankshaft reluctor wheel reference gap to identify crankshaft position.
This information is then used to sequence the ignition timing and fuel injection events for the engine. The ECM also uses CKP sensor output
information to determine the crankshaft relative position to the camshaft, to detect cylinder misfire, and to control the CMP actuator if equipped.
Motor Control Module (MCM) 1 is also connected to the CKP sensor signal and low reference circuits. The MCM uses the CKP sensor output
information to determine engine crankshaft position to aid in smooth engine Auto-starts. The MCM does not need the CKP sensor signal in order
for the engine to start and run.
Conditions for Running the DTC
P1AC6 and P1AC7
* Drive motor generator 1 is rotating.
* The DTC runs continuously when the above conditions are met.
Conditions for Setting the DTC
P1AC6
The MCM detects no engine speed signal for 2 seconds.
P1AC7
The MCM detects an invalid engine speed signal for 3 seconds.
Action Taken When the DTC Sets
DTCs P1AC6 and P1AC7 are Type B DTCs.
Conditions for Clearing the DTC
DTCs P1AC6 and P1AC7 are Type B DTCs.
Diagnostic Aids
With an ECM DTC P0335 set, the engine will only crank for about 2 seconds.
Reference Information
Schematic Reference
* Hybrid Controls Schematics ()
