Tandem Solenoid Starter (TSS) Motor Stop/Start Strategy

WARNING: This page is about a different car, the 2019 Jaguar XE. However, it is still accessible from the selected car via links, so may be relevant.

The Tandem Solenoid Starter (TSS) motor and the stop/start system allows the vehicle engine to be restarted during an engine stop cycle, allowing the driver to proceed before the engine comes to a complete stop. This would not be possible without the TSS motor.

The feature of the motor and the pinion gear being operated individually allows meshing of the pinion gear with the ring gear even if the engine is still operating. This allows seamless stop/start without hesitation.

Engine Speed Above 350 RPM:

When the engine stop is initiated, the engine speed is at or above 350 RPM and the PCM detects engine restart parameters resulting from a driver action or system request, the PCM activates the fuel injection system to allow the engine to continue to operate. The TSS motor is not operated for an engine start under these conditions.

Engine Speed Between 200 and 350 RPM:

When an engine stop is initiated, the engine speed is between 200 and 350 RPM and the PCM detects engine restart parameters resulting from a driver action or system request, the PCM operates the TSS motor to first accelerate the pinion gear up to the ring gear speed and then to engage the pinion gear with the ring gear to rotate the engine up to starting RPM. The PCM activates the fueling and engine systems to allow a restart.

Engine Speed Below 200 RPM:

When an engine stop is initiated, the engine speed is at or below 200 RPM and the PCM detects engine restart parameters resulting from a driver action or system request, the PCM operates the TSS motor to first engage the pinion gear with the ring gear and then operate the motor to rotate the engine up to starting RPM. The PCM activates the fueling and engine systems to allow a restart.

TRAILER TOWING

The auto stop/start system will automatically disable when trailer lights are detected by the BCM/GWM assembly, this information is then transmitted to the PCM. It is not possible for the system to detect when a trailer power plug is inserted in the vehicle towing connector, so it uses operation of the trailer lights as its indicator.

The trailer towing system inhibits auto stop/start operation as it is possible that trailer power requirements could interfere with the operation of the battery monitoring system. In particular, a trailer battery could reverse the feed current to the vehicle during an engine cranking event, this could possibly confuse the battery monitoring system into detecting an unrealistically small current at engine cranking.