Hybrid Controls: Other Chevrolet Silverado Classic 3500

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 engine cranking, torque control, speed control and torque smoothing/active damping functions. The SGCM also controls the 4 types of power

1. Perform bi-directional 42-volt DC to 14-volt DC electrical energy conversion between the 42-volt DC bus and the 14-volt DC bus for system energy management.
2. Perform bi-directional DC/AC electrical energy conversion between the 42-volt DC bus and the 3-phase asynchronous machine.
3. Provide 120-volt 60Hz AC energy for on and off board electrical equipment.

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 2 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.

Reference Information

Schematic Reference

Hybrid Controls Schematics

Connector End View Reference

Hybrid Controls Connector End Views

Electrical Information Reference

1. «Circuit Testing»(ref-277884-S17422072462008012100000)
2. «Connector Repairs»(ref-277884-S12371167392008012100000)
3. «Testing for Intermittent Conditions and Poor Connections»(ref-277884-S20700666652008012100000)
4. «Wiring Repairs»(ref-277884-S08861102212008012100000)

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 (5.3L Engine w/RPO HP2)»(ref-277905-S03299159022008012100000) . 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 (5.3L Engine w/RPO HP2)»(ref-277905-S03299159022008012100000) . 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.

Repair Procedures

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Generator Control Module Replacement (5.3L Engine w/RPO HP2)»(ref-277905-S34567908452008012100000)
2. «Generator Control Module 3-Phase Cable Assembly Replacement (5.3L Engine w/RPO HP2)»(ref-277905-S03299159022008012100000)
3. «Generator Stator Replacement (5.3L Engine w/RPO HP2)»(ref-277905-S37765744902008012100000)

Tools Required

J 46093 Rotor and Flexplate Holding Tool

Hybrid Control Module (HCM)

The hybrid control module (HCM) is located on the engine fan shroud near the powertrain control module (PCM). It acts as a gateway between the high-speed GMLAN and Class 2 local area networks. If a module in the high-speed system needs to pass information to the Class II bus, it tags that message and passes it on to the HCM; the HCM reads the message and passes it along to the appropriate network. For example, if the starter generator control module (SGCM) needs to display a warning or alert the driver to a change in operating mode, the HCM would take that message from the high speed link and pass it to the display controller, which is on the Class II system. The HCM also

1. Controls automatic engine starts and stops
2. Controls the energy flowing into/out of the 14-volt and 42-volt batteries
3. Enables and disables power for the auxiliary power outlets
4. Enables and disables surge smoothing/active damping
5. Disables energy generation after airbag deployment
6. Controls the auxiliary transmission pump, the power maintenance relay, and the auxiliary heater pump
7. Controls starter generator speed during transmission downshift assists-The downshift assists support the engine during un-fueled downshifts from 4th to 3rd gear and 3rd to 2nd gear. The HCM calculates a target engine speed and uses the starter generator to maintain that target. The starter generator has to control engine speed, using a torque command, which is within the upper and lower torque limits specified by the HCM.

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 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.