Description And Operation

DESCRIPTION 

Courtesy of CHRYSLER GROUP, LLC

The starting system can consist of the following components:

1.	Refer to GENERATOR  - Standard, Remote, ESS.
2.	Refer to STARTER MOTOR  - Standard, Remote, ESS.
3.	Refer to PARK/NEUTRAL SWITCH  (Automatic Transmission) - Standard, Remote, ESS.
4.	Refer to LOW FREQUENCY ANTENNAS  - Standard, Remote, ESS.
5.	Refer to LIFTGATE AJAR SWITCH  - Standard, Remote, ESS.
6.	Refer to RADIO FREQUENCY HUB (RFH) MODULE  - Standard, Remote.
7.	Refer to FUEL PUMP CONTROL MODULE  - Standard, Remote, ESS.
8.	Refer to DOOR AJAR SWITCH  - Standard, Remote, ESS.
9.	Refer to KEYLESS IGNITION NODE (KIN)  - Standard, Remote, ESS.
10.	Refer to INSTRUMENT PANEL CLUSTER (IPC)  - Standard, Remote, ESS.
11.	Refer to BODY CONTROL MODULE (BCM)  - Standard, Remote, ESS.
12.	Refer to BATTERY  - Standard, Remote, ESS. The Stop/Start system will also equip a supplemental battery.
13.	Refer to INTELLIGENT BATTERY SENSOR (IBS)  - Standard, Remote, ESS.
14.	Refer to POWERTRAIN CONTROL MODULE (PCM)  - Standard, Remote, ESS.
15.	Refer to HOOD AJAR SWITCH  - Standard, Remote, ESS.
-	Refer to CLUTCH PEDAL SWITCH  (Manual Transmission) - Standard, Remote, ESS.

Other components not shown:

1. Brake Pedal Position Sensor  - Standard, Remote, ESS
2. Power Control Relay (PCR)  - ESS
3. Remote Keyless Entry FOBIKS  - Remote
4. Remove Start Antenna  - Remote
5. Voltage Regulator  - ESS
6. Voltage Stability Module (VSM)  - ESS

OPERATION 

STARTING  - When the operator presses the Start/Stop Button on a KIN, the FOBIK is validated wirelessly by the RFH module. If the FOBIK is recognized as belonging to the vehicle and is inside the vehicle, the system allows the ignition state of the vehicle to be changed between the LOCK, ACCESSORY, RUN, and START ignition states.

Refer to COMPONENT INDEX .

Vehicles equipped with ESS have two batteries, a cranking battery (large battery) and an accessory battery (small battery). Both batteries are charged together when the Power Control Relay (PCR) is closed. Once the vehicle is running and the Stop/Start event takes place the PCR relay open the connection and isolated the accessories from the cranking battery so that there is no voltage interruption to the vehicle.

Refer to COMPONENT INDEX .

• Is the gateway module used to converts BUS messages and then broadcasting them from one bus to another.
• reads the state of the door, liftgate and hood switches before enabling CRANK
• the BCM is responsible for actuating the low side of starter relay once commanded by the PCM high side relay CRANK command.
• Receives over LIN bus with the IBS information about raw battery current, voltage, and temperature levels.
• is responsible for deactivating the starter motor.

Refer to COMPONENT INDEX .

Manual Transmission Equipped Vehicles 

• Used to indicate the position of the clutch pedal.

Refer to COMPONENT INDEX .

• Used to indicate if any doors on the vehicle or opened or closed.

Refer to COMPONENT INDEX .

• Signaled by the PCM to drive the fuel pump to support engine starting.

Refer to COMPONENT INDEX .

Refer to COMPONENT INDEX .

• Used to indicate if the hood is in the open or close state.

Refer to COMPONENT INDEX .

The Keyless Go feature requires the vehicle to be equipped with an IPC display for prompts and status information. The display messages are:

• Service Keyless System
• FOB Not Detected
• FOB Left Vehicle
• Not in Park
• Push Brake Pedal and Push Button to Start
• Push Clutch Pedal and Push Button to Start
• Vehicle not in Park Warning

Refer to COMPONENT INDEX .

• The IBS interacts with the BCM by means of LIN bus communications. The BCM is its master node.
• Used to give information about raw battery current, voltage, and temperature levels.

Refer to COMPONENT INDEX .

• Used to broadcast the start button status

LED Indicator Operation:

The LEDs in the Start/Stop Button provide visual indication of the ignition system and button use to aid the driver. The Logic for LED control is implemented in the RFH module. The Start/Stop Button contain four LEDs:

• OFF Indication
• ACC Indication (Accessory)
• ON Indication (ON or RUN)
• Ignition Switch Indicator (button backlight)

The RFH module will log a DTC indicating an incorrect Ignition status value is present; in this state the ignition status is unknown. This will continue until the correct signal is received by the RFH module.

• Receives in put from the Stop/Start button.
• Notifies the RFH module through a hardwired signal of the Stop/Start button status is ACTIVE.
• Broadcasts over LIN the ignition switch position data to the RFH module

Refer to COMPONENT INDEX .

• Challenged by the RFH module during start request to indicate if the liftgate is open or closed.

Refer to COMPONENT INDEX .

• Used in validation of the FOBiK being preset during start request.

Refer to COMPONENT INDEX .

Automatic Transmission Equipped Vehicles 

• Used to indicate the position of the gear shift lever.

Refer to COMPONENT INDEX .

• PCM turns on the high side of the PCM starter relay
• turns the crank hold signal to true enabling the BCM to turn on the low side of the starter relay
• disables double start over ride once the engine is started

Refer to COMPONENT INDEX .

The RFH module validates the key using the LF antennas and:

• receives the input request to start from the KIN
• energizes the key transponder in order to read it
• sends a random code to the transponder and in return, receives a crypt code from the transponder
• validates the key or fob using low frequency antennas
• validates that the brake is engaged
• sends a request to the BCM to change the ignition state

Refer to COMPONENT INDEX .

• Incorporates the starter solenoid.
• The starter consists of a DC motor powered by the battery and an electromagnet exciter.
• The starter is operated by a single relay positioned in the Power Distribution Center (PDC) and activated by the PCM.
• The starter for the Stop/Start equipped vehicle is heavy duty.

BRAKE PEDAL POSITION SENSOR 

• used to verify the brake pedal is pressed during ignition start. Read by the BCM.

REMOTE KEYLESS ENTRY FOBiKS 

• used in the vehicle start authentication process by identifying the key transponder.
• includes the key transponder

How does ESS function - simple overview:

• The ESS system shuts the engine off when the vehicle stops.
• The vehicle has to be stopped for a pre-set time before the engine is switched off.
• Then, it restarts when the driver releases the brake to move the vehicle.
• The ESS system senses brake pedal position and vehicle speed to determine that the vehicle is moving.
• Powertrain calibration makes the decision when to shut off the engine and when to restart the engine again.
• The ESS system operation is mostly transparent to the driver.
• When the engine stops, a smaller secondary battery keeps accessory features powered, like the fan, wipers, headlights, audio system, etc.
• A PCR relay between the two batteries smooth out voltage dips when the starter cranks the engine.

Primary Autostop Enablers  - Brake pedal depressed (automatic transmission).

Secondary Autostop Enablers  - Vehicle speed, coolant temperature, hood closed, doors closed, driver's seat belt latched, interior climate and settings, battery state and energy demand, steering wheel angle, steering wheel torque, ambient temperature, time and speed since last autostop, transfer case position, and ESC status, No stop-start related faults present.

Autostop Events 

• Autostop state broadcast on CAN Bus.
• Cluster telltale illuminates.
• Engine shutdown begins.

As the engine slows it passes through three phases:

• Fuel and spark restart permissible.
• Restart prohibited.
• Restart permitted, based on start system employed.

Autostart requests are evaluated throughout the autostop event.

When in autostop: 

• IPC ESS telltale remains illuminated.
• IPC displays the autostop state message.
• BCM starter relay is energized providing the PCM with direct starter control.

Vehicle Function: 

• Consumer electronics continue to function in a normal manner.
• HVAC fan speed and other setting adjusted to maximize cabin comfort and autostop duration (based on climate control settings and conditions).
• Electric Power Steering (EPS) maintained during autostop, possibly with reduced maximum assist.

System Requested Autostarts: 

• Battery State.
• Brake Vacuum.
• Climate control stress.
• Vehicle speed.
• Steering wheel angle or torque.
• Transmission selector position.

Stop-Start Disable (while autostopped) 

• Vehicle systems monitored that may disable ESS (requiring a key restart if in autostop) include: hood opened, occupant sensing indicating driver not present, unsafe gear shift position for autostart and critical system faults.

Autostart Decision: 

• All autostart enablers present.
• Brake pedal released or shifter place in reverse (automatic transmissions).
• Clutch pedal depressed past the up-stop position (manual transmission).
• Throttle pedal depressed.

Autostart Events: 

• Autostart state broadcasted on the CAN bus.
• instrument cluster stop/start telltale illumination cancelled.
• IPC display changed to previous IPC message (outside temp and compass, etc).
• A VSM is placed into a voltage conditioning mode.
• Hill Assist requested.
• Starter relay commanded to initiate cranking.
• Engine achieves idle speed.

Launch Events: 

• Automatic transmission clutches engaged.
• Hill assist released.
• Climate control returned to pre-autostop conditions.
• ESS ready state broadcast on the CAN bus.
• Embedded IPC ESS system message indicating "Stop/Start Ready".

Planned Autostart (Engine On) Enable Conditions:
1. Valid target gear and brake switch pressure condition.
2. Completed initial engine key start.
3. Occupant sensing allow engine start condition met.
4. On Board Diagnostics (OBD) allow engine start condition met.
5. Vehicle hood not Ajar.

Potential Autostop (Engine Off) Enable Conditions:
1. Tow Haul mode not active.
2. Steering wheel angle within defined range.
3. Steering wheel angle gradient within defined range.
4. Steering column torque within defined range.
5. Battery health state of function greater than threshold.

Planned Autostop (Engine Off) Enable Conditions:
1. Valid target gear and brake switch pressure state combination.
2. Threshold vehicle speed exceeded or timed-out since last shift out of reverse.
3. Transmission ready.
4. 4WD Low mode not active.
5. Starter cool down condition met after reaching max allowable consecutive restarts.
6. Ambient temperature within defined range.
7. Engine coolant temperature within defined range.
8. Catalyst temperature within defined range.
9. Battery temperature within defined range.
10. Barometric pressure greater than threshold.
11. Brake booster delta pressure less than threshold.
12. Fuel level greater than threshold.
13. Vehicle hood not Ajar.
14. No throttle request.
15. No engine stop inhibit request by HVAC.
16. Battery state of charge greater than threshold.
17. Battery voltage state of function greater than threshold.
18. Engine speed less than threshold.
19. Vehicle speed less than threshold.
20. Threshold vehicle speed exceeded since last engine start.
21. Occupant sensing allow engine stop condition met.
22. OBD allow engine stop condition met.
23. Engine runtime greater than threshold.
24. ESS "Off" switch not activated.
25. Flex fuel learn mode not active.
26. ABS brake event not present.

Pop Up Messages displayed on the IPC 

- IPC message states Stop/Start Autostop Active 

• No Chime.
• Normal Use.
• Pop-up maintained for 5 seconds.
• Displays with green hard telltale.

Stop/Start To Restart Press 

• Single Chime.
• Driver put gear shift in gear without using Clutch; customer needs to return to Neutral or fully depress clutch pedal.
• Pop up maintained for 5 seconds.

Stop/Start Restart Required Fault Detected 

• Single Chime.
• MIL or ESS system fault preventing safe state confirmation during autostop.

Pop Up Messages displayed within IPC "Ring" menu 

Stop/Start Ready 

• Stop-Start conditions met to enable engine stop.

Stop/Start Off 

• Stop-Start turned off by the customer at the switch.

Stop/Start Not Ready 

• Stop-Start conditions are not met to enable engine stop (ex: HVAC settings, engine temperature, etc).

Stop/Start Not Ready Steering Wheel Turned 

• Stop-Start condition not met with steering wheel turned past calibrated angle.

ENGINE STOP- START (ESS) OPERATION 

ESS specific components or component changes:

• Transmission 

  -

  • New thermal management system for maintaining optimum operating temperature
  • Vehicle launch control coordination with engine and brake system
• Voltage Stability Module (Single Battery ONLY)  - ESS applications feature a single Voltage Stabilization Module (VSM) (located within the dashboard) to protect for variations of the voltage supply to the Radio Receiver Module (RRM) during an engine restart/warm crank.

  The VSM wakes up on the ignition run/start relay within 150-250ms. During engine warm start crank, the VSM will start stabilizing within 0.015 sec of receiving the ignition crank. The VSM is capable of maintaining voltage 12V +/- 0.5 from start of the crank for up to 5 sec +/- 0.2. The VSM starts stabilizing with a source voltage as low as 11 volts and continues stabilizing with a max rated load with a source voltage of 7 volts and as low as 6 volts without any loads. If the source voltage is higher than the stabilized for 0.010 seconds by a minimum of 0.20 volts before 5 seconds, then the stabilization stops within 5 ms allowing the source voltage to bypass without interruption.

• Batteries - Vehicle Battery and Cranking Battery 

  - During cranking, both batteries work together to provide a starter load. During a stop/start event, the two batteries work separately:

  • The smaller vehicle battery supports the vehicle Ignition off electrical load.
  • The Larger cranking battery supports the re-start event.
• Power Control Relay 

  - The Power Control Relay (PCR) is placed in between the Cranking Battery and Auxiliary Battery.

  • For automatic cranking, the Dual Battery Control Relay will close when the controller receives an ESS indication that the vehicle will start soon, this will cause the PCR to open the contact.
  • The Dual Battery Control Relay will be closed for a calibrated time or until the engine RPM reaches a calibrated limit. Once either condition has occurred, the Dual Battery Control Relay will be open again causing the PCR to close the contact.
• The PCR is diagnosed for OBDII requirement that consists of stuck open and stuck closed:
  • For Stuck Closed PCR, diagnostics can determine failure based on voltage during auto-cranking and engine not running. If a Stuck Closed Diagnostic Trouble Code (DTC) is matured, the PCM sets a signal for the IPC to display generic service ESS messages.
  • For Stuck Open PCR, diagnostics can determine failure based on voltage during: Key On-Engine On (KOEO), and Autostop. If a Stuck Open DTC is matured the PCM sets a signal for the IPC to display a specific message.
• In vehicles with a diesel engine:
  • For Stuck Open PCR, diagnostics can determine failure based on voltage during: KOEO, and Autostop. If a Stuck Open DTC is matured the PCM sets a signal for the IPC to display a specific message. PCR diagnostics is determined by monitoring PCM battery input (hardwire) and IBS voltage CAN-C signal and comparing difference to calibration thresholds for stuck open and stuck closed. If Dual Battery Control Relay OBD1 is faulted or IBS voltage CAN-C signal is SNA or no signal, PCR open/closed diagnostics must be disabled.
  • For Stuck Closed PCR, diagnostics can determine failure based on voltage during auto-cranking and engine not running. If a Stuck Closed DTC is matured, the PCM sets a signal for the IPC to display a generic service ESS messages.
• In vehicles with an EVR alternator, PCR diagnostics is determined by monitoring PCM battery input (hardwire) and generator sense (hardwire) and comparing difference to calibrated thresholds for stuck open and stuck closed. If the Dual Battery Control Relay OBD1 is faulted OR generator sense circuit is faulted, the PCR open/closed diagnostics must be disabled.
• In vehicles with a LIN alternator, PCR diagnostics is determined by monitoring PCM battery input (hardwire) and the IBS voltage CAN-C signal and comparing differences to calibration thresholds for stuck open and stuck closed. If Dual Battery Control Relay OBD1 is faulted OR IBS voltage CAN-C signal is Signal Not Available (SNA) or no signal, the PCR open/closed diagnostics must be disabled.
• Door Ajar Switch 

  -

  • The driver door ajar switch for stop/start vehicles has two diagnostic resistors installed in the latch assembly circuit. This resistor allows the Body Control Module (BCM) to detect an open or shorted condition in the circuit.
• Engine 

  -

  • Lubrication system and wear components to manage increased stop and start frequency.
• Engine Mounts 

  -

  • Modified based on starter packaging. This may be unique for every engine and vehicle.
  • Optimized for Noise Vibration Harshness (NVH) given increased ESS event frequency.
• Electronic Stability Controls (ESC) 

  -

  • Provides brake controls using Hill Start Assist (HSA) during autostart and transmission engagement transition to prevent vehicle movement while in an autostop condition during the transition from brake pedal to accelerator pedal. Brakes to be released commensurate with torque request and torque capacity
  • Ensure module compatibility with cranking during HSA function (voltage drop, etc.)
  NOTE:

  When the ESC system is deactivated (OFF) the LED light in the button will be illuminated.

• Flywheel / Drive Plate 

  -

  • Revised ring gear with chamfered, hardened gear teeth to improve starter pinion engagement and reduced gear tooth wear
• Generator 

  -

  • Higher output alternator to provide greater charging capacity immediately following autostarts.
  • No requirement for voltage regulation on the ESS system.
• Intelligent Battery Sensor (IBS)  - The IBS is responsible for measuring the state-of-charge. It will also predict voltage and capacity (ah) for future crank events. The IBS is also responsible for measuring battery temperature and alternator voltage current.
• Instrument Panel Cluster (IPC) 

  -

  • Revised IPC with stop-start specific graphics and IPC messaging.
• Body Control Module 

  -

  • Modified BCM for communications and starter control.
• Hood Switch 

  -

  • To prevent an autostart while the hood is in a raised position, a secondary hood switch is added to provide redundant hood position sensing.
  • The secondary hood switch is wired to the PCM.
• HVAC Head Unit and Controls 

  -

  • Added control features to provide interior climate management.
  • Fan speed control adjusted during autostop.
  • Autostop inhibit and autostart request based on combination of interior temperature, sun loading and variation from temperature set point and/or ambient temperature. This may inhibit some autostops or reduce autostop duration.
• Powertrain Control Module (PCM) 

  :

  • Circuit board population for added inputs and outputs.
  • ESS event coordinator added to manage all autostop and autostart activity.
  • Impact on torque, security, OBD and end of line diagnostics.
• HBC/ESC Vacuum Sensor 

  -

  • Switch in vacuum hose connector to initiate engine restart in case of low vacuum.
• Radio Head Unit and Integrated Center Stack 

  -

  • Added ESS specific messaging and menu selections.
• Starter (High Durability) 

  :

  • Enhanced starter with increased life brushes, needle bearings, pre-loaded pinion gear spring and other changes to enhance longevity and improve NVH
  • Starter power increased to compensate for brush losses and to increase cranking speed
  • A PCR relay is required to achieve minimum system voltage drop requirements of critical modules and devices and autostop duration and frequency objectives.
• ESS Disable Switch 

  -

  • New hard switch located in the center stack switch bank.
    NOTE:

    When the Stop/Start system is deactivated (OFF) the LED light in the button will be illuminated.