Stop/Start System Diagnosis - Ess Equipped
WARNING: This page is about a different car, the 2022 Chrysler Voyager and 2022 Chrysler Pacifica. However, it is still accessible from the selected car via links, so may be relevant.
For diagnostics of the Stop Start system, the scan tool can be used to review the Stop Start Data to help root cause a potential Stop Start concern.
With the scan tool, under ECU, System Test, Stop & Start Data review any data that will inhibit the ESS.
For diagnostics of the basic starting system. Refer to DIAGNOSIS AND TESTING .
For diagnostics of the Stop/Start system, the scan tool can be used to review the inputs/sensor values and DTCs to help root cause a potential Stop/Start concern.
With the scan tool, select OBDII monitors, Engine Stop/Start Status, check for a "False" status to help root cause a potential Stop/Start concern.
Possible Reasons The Engine Does Not AUTOSTOP
Prior to engine shut down, the PCM will check many safety and comfort conditions to see if they are fulfilled.
A Stop/Start Not Ready message and the inhibit reason may display in the Electronic Vehicle Information Center (EVIC).
| EVIC Warning Messages for ESS | |
|---|---|
| ESS EVIC Message | ESS EVIC Message Reason/Repair Action |
| Stop/Start Not Available | During ECM wake-up and Stop/Start not ready at key On indicating engine off. |
| Stop/Start Active | Indicates engine is off during an Autostop. |
| Stop/Start Not Ready Driver Seatbelt Unbuckled | Driver's seatbelt is unbuckled prior to an Autostop. |
| Stop/Start Not Available Driver Not Detected | Driver Presence Detection Module indicates driver's seat is unoccupied for applications with removable doors only. |
| Stop/Start Not Ready Driver Door Open | Driver's door is open, prior or during an Autostop. |
| Stop/Start Press Clutch or Shift To Neutral | Shifting into gear during an Autostop without pressing the clutch. (For MTX vehicles only). |
| Stop/Start Restart Required Fault Detected | During an Autostop/Autostart, the ECM detects a DTC calibrated to be an Engine Start inhibit trigger. Repair DTCs and retest. |
| Stop/Start Not Available Service Battery | Voltage Less than 11.5 V (trigger Autostart when below 11.5 V) Battery State Of Charge (SOC):
Battery temperature is greater than 140°F (60°C) Battery temperature is less than 5°F (-15°C) Main 12 Volt Battery does not successfully pass a load test or Battery is sulfated. Auxiliary Battery does not successfully pass a load test or Battery is sulfated. |
| Stop/Start Fail | During engine running, ECM detects a DTC calibrated to be an Engine Off inhibit trigger. Repair DTCs and retest. |
| Stop/Start Not Available | Message Indicates "not ready" during engine running and any of the Engine Off AND Engine Start conditions are FALSE . |
| Stop/Start Ready | ATX: while vehicle is moving and during engine running, ESS ready to allow an Autostop (all Engine Off AND Engine Start conditions are true) ESS will enter an Autostop once Trans Ready For ESS = True, Master Cylinder Pressure is above threshold, and Vehicle speed is below threshold. MTX: While vehicle is moving and engine running, ESS ready to allow an Autostop (all Engine Off AND Engine Start conditions are true) once Vehicle speed is below threshold, Gear is in Neutral and Clutch pedal is released. |
| Stop/Start Off | Indicates ESS disable switch pressed, ESS is inhibited. No Autostop while engine running. Autostart if ESS disable switch pressed during Autostop. ESS disable switch status resets with every key cycle. |
| Stop/Start Not Ready Hood Open | Indicates hood is open. Inhibits Autostops while engine running. |
| Stop/Start Not Ready Accelerator Depressed | Vehicle speed below Autostopping threshold, brake pedal is pressed AND accelerator pedal is pressed. Inhibits Autostops while engine running. Initiates an Autostart during an Autostop. |
| Stop/Start Not Ready Battery Charging | Voltage Less than 11.5 V (trigger Autostart when below 11.5 V) Battery State Of Charge (SOC):
Battery temperature is greater than 140°F (60°C) Battery temperature is less than 5°F (-15°C) Main 12 Volt Battery does not successfully pass a load test or Battery is sulfated. Auxiliary Battery does not successfully pass a load test or Battery is sulfated. |
| Stop/Start Not Ready Battery Protection Mode | Verify that the SOF status is not "False." |
| Stop/Start Not Ready Tow Active | When Tow/Haul mode is active, ESS is inhibited. Autostart is triggered if Tow/Haul Switch is pressed during an Autostop. |
| Stop/Start Not Ready 4Low Active | T-Case is in 4Wheel Low mode. Present on vehicles with T- Case (4Wheel Low). |
| Stop/Start Not Ready Too Steep | Indicates grade above calibrated threshold to allow Autostop. Triggers an Autostart during an Autostop if grade threshold is above calibrated threshold. |
| Stop/Start Not Ready Cabin Cooling or Heating | Indicates HVAC demand via the CAN C Bus. |
| Stop/Start Not Ready Max Cooling or Heating | When HVAC max button is pressed by customer. Indicates HVAC demand via CAN C signal. Inhibits Autostops while pressed. Triggers an Autostart if pressed during an Autostop. |
| Stop/Start Not Ready Defrost Active | Indicates Front Defrost active. Triggers an Autostart during an Autostop and inhibits Autostops if active during engine running. |
| Stop/Start Not Ready Turned Steering Wheel | Indicates steering wheel is above calibrated threshold. Inhibits Autostops if present during engine running. Triggers Autostarts if active during and Autostop. |
| Stop/Start Not Ready Engine Temperature Too Low | Indicates either coolant, or oil, or catalyst engine temperature is lower than calibrated threshold. Inhibits Autostops during engine running and triggers an Autostart during an Autostop event. |
| Stop/Start Not Ready DEF RGN | During engine running, ECM inhibits Autostops when Regen is active. |
| Stop/Start Not Ready Service Battery Vehicle Shut Off | During a failure of the Power Control Relay (PCR). After an Autostop: If Power Control Relay between Cranking Battery and Auxiliary Battery is stuck open, vehicle shuts off within minutes. |
The engine will NOT Autostop unless ALL conditions below are TRUE .
If ANY of the conditions below are NOT TRUE Autostop is INHIBITED .
| ESS Allow Conditions for Autostop | |
|---|---|
| Condition | Operating Range |
| Outside Ambient temperature | Greater than 10°F (-12°C) or less than 110°F (43°C) |
| Driver seatbelt | Buckled |
| Driver door | Closed |
| Driver seat pad Driver Presence Detection Module (if equipped) | Occupied - when equipped (on vehicles with removable doors) |
| Hood | Fully closed (2 Hood Ajar Switch Inputs) |
| Accelerator pedal | Released |
| Grade -too steep of an incline/decline | Lesser than +7% OR greater than -10% |
| Engine operating temperature | Minimum acceptable range: Coolant temperature greater than a calibrated threshold (Function of ambient temp) Engine Oil temperature is greater than a calibrated threshold (Function of ambient temp) Catalyst temperature is greater than a calibrated threshold (Function of ambient temp) Maximum acceptable range: Coolant temperature below a calibrated threshold 239°F (115°C) Engine Oil temperature below a calibrated threshold 239°F (115°C) Catalyst temperature below a calibrated threshold 1742°F (950°C) |
| Transfer Case Selection | 4WD LO = Off Neutral = Off |
| Manual Paddle shifter | Not selected/active/pressed |
| Shifter position | Drive (NAFTA ATX) Neutral (NAFTA MTX) |
| Brake Master Cylinder pressure | Above a calibrated threshold (ATX only) |
| Hill start assist | Hill start assist brake pressure above calibrated threshold |
| ESS related OBD faults | No Active OBD DTCs |
| Brake Booster Vacuum | 29.9 kPa (4.34 psi) |
| Steering Angle | Below 135 degrees |
| Tow Haul Mode | Off |
| ESS Disable Button | Not pressed |
| PPPA (Parallel Perpendicular Park Assist) | Not active |
| Altitude | Barometric pressure above: 72 KPa (less than 9, 000 ft.) |
| Brake Pedal | Pressed (while maintaining steady Brake Pedal pressure applied by driver) |
| ABS Module | Anti-lock brake system is not active |
| Engine Speed | 1100 RPM |
| ACC+ | Stop/Start allowed |
| Engine run time | 2 seconds |
| Vehicle speed | 0 MPH\0 km/h (ATX) |
| Threshold vehicle speed exceeded since last engine Autostart | 5 MPH |
| 12 volt Battery Parameters | Voltage more than 11.5 Volts SOC above 65% Temperature below 140°F (60°C) |
It may be possible for the vehicle to be driven several times without the Stop/Start system going into a Stop/Start ready state under more extreme conditions of the conditions listed above.
When it comes to Stop/Start, the PCM allows the engine Autostart during an Autostop event when any of the below conditions are TRUE .
| ESS Allow Conditions for Autostart | |
|---|---|
| Condition | Operating Range |
| Ambient temperature | Less than 10°F (-12°C) or greater than 110°F (43°C) |
| Shifter Position | For NAFTA: Out of Drive or M-Gate For EMEA: Neutral / Reverse |
| Accelerator Pedal | Pressed |
| HVAC mode: |
|
| HVAC blower speed | Max blower speed selected or blower speed incremented |
| Grade-too steep of an incline/decline | Greater than +7% OR lesser than -10% |
| Engine operating temperature | Minimum acceptable range: Coolant temperature less than a calibrated threshold (Function of ambient temp) Engine Oil temperature is less than a calibrated threshold (Function of ambient temp) Catalyst temperature is less than a calibrated threshold (Function of ambient temp) Maximum acceptable range: Coolant temperature above a calibrated threshold 239°F (115°C) Engine Oil temperature above a calibrated threshold 239°F (115°C) Catalyst temperature above a calibrated threshold 1742°F (950°C) |
| Stop/Start Autostop time active | Exceeded 5 minute timeout |
| Transfer Case Selection | 4WD LO = ON Neutral = ON |
| Manual Paddle shifter | Active/Pressed during Autostop |
| Shifter position | Autostart when shifter moved out of Drive |
| Brake Master Cylinder pressure | Below a calibrated threshold (Below 3bar) Or below a calibrated pressure gradient threshold (ATX only) |
| Hill Start Assist | Hill Start Assist brake pressure below calibrated threshold |
| ESS related OBD Faults | Calibrated active to allow Autostart Example: U0131-00 active DTC |
| Brake Booster Vacuum | 29.9 kPa (4.34 psi) |
| Steering Angle | Above 135 degrees |
| Tow Haul Mode | On |
| ESS Disable Button | Pressed |
| PPPA (Parallel Perpendicular Park Assist) | Activated |
| Brake Pedal | Released |
| ACC+ | Cancelled/disengaged |
| Vehicle speed | Above 0 MPH/0 km/h (ATX) Above 1.5 MPH/3 km/h (MTX) |
| 12V Battery Parameters | Voltage Less than 11.5 V (trigger Autostart when below 11.5 V) SOC Below 65% Temperature Above 140°F (60°C) Main 12 Volt Battery does not successfully pass a load test or Battery is sulfated. Auxiliary Battery does not successfully pass a load test or Battery is sulfated. |