Engine Will Not Crank HP2

Important: This diagnostic to be used without any DTC's set, and a Engine Will Not Crank symptom.

Important: Always perform the Diagnostic System Check - Engine Electrical prior to using this diagnostic procedure.

Starter/Generator

Instead of a conventional starter motor and generator, the PHT uses a compact 14-kW electric induction motor or starter generator integrated in a patented, space-efficient manner between the engine and transmission. The starter generator provides fast, quiet starting power and allows automatic engine stops and starts to conserve fuel. It also smooths out any driveline surges, generates electrical current to charge the batteries, runs auxiliary power outlets, and provides coast-down regenerative braking as an aid to fuel economy. The starter generator includes a rotor and stationary stator, housed inside the transmission bell housing. The stator is attached to the engine block and incorporates high efficiency/smaller package size coils formed by laser welding copper bars together instead of winding with copper wire. The rotor bolts directly to the engine crankshaft and spins inside the stator. Current flowing through the stator's electric windings via the 3-phase cables, generates magnetic forces in the rotor, which causes the rotor to turn, starting the engine. The starter generator is in series with the engine, connected directly to it, so that anytime the engine is turning, the Starter Generator is turning and vice versa. An auxiliary transmission oil pump helps enable the automatic start feature by assuring sufficient line pressure to allow torque transfer immediately upon driver command, when the engine is started.

Starter/Generator Control Module (SGCM)

The starter generator control module (SGCM) controls the flow of torque/energy into and out of the starter/generator via the 3-phase cables. Overall, the SGCM controls the starter generator's engine cranking, torque control, speed control and torque smoothing/active damping functions. The SGCM also controls the four types of power:

In the basic, 3-phase inversion/conversion process, 42-volt DC is converted to AC for starting, and, conversely, AC is converted to 42-volt DC for recharging. In addition, 14-volt power is converted to 42-volt for jump-starting, 42-volt power is converted to 14-volt for the battery charging function, and 42-volt power is converted to 120 volts AC for powering the auxiliary power outlets.

The SGCM has two discrete crankshaft signal circuits inputs to calculate engine position. One is hard wired and one is a signal on the GMLAN bus. This acts as a back-up system in the event that one signal is interrupted the engine will be able to start and run although a DTC will set.

If the stator has developed an internal short, the strong smell of melted wiring or insulation may be evident.

Schematic Reference

Starting and Charging Schematics

Connector End View Reference

Engine Electrical Connector End Views

Electrical Information Reference

Important: 

1. Turn the ignition OFF.
2. Disconnect the 3-phase cable from the Stator (Electric Machine). Refer to Generator Control Module 3-Phase Cable Assembly Replacement . Test for shorts between the stator connections, and to chassis ground.

⇒	If a short is confirmed, replace the Starter Generator Stator.

3. Disconnect the 3-phase cables from the SGCM. Refer to Generator Control Module 3-Phase Cable Assembly Replacement . Test the 3-phase cables circuits for shorts between cables, and short to chassis ground.

⇒	If a short is confirmed, replace the 3-phase cables.

4. If no trouble found, replace the SGCM.