Stop/Start System Diagnosis - Ess Equipped
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.
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).
The engine will NOT Autostop unless ALL conditions below are TRUE
| 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 kph (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 items 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 kph (ATX) Above 1.5 MPH/3 kph (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) |
System Malfunction:
If there is a malfunction in the Stop/Start system, the system will not shut down the engine. A "SERVICE STOP/START SYSTEM" message will appear in the Electronic Vehicle Information Center (EVIC) with amber Autostart telltale warning light.