Diagnostic Overview - ESIM Switch Stuck Closed (P0452) Diagnostic

ESIM SWITCH STUCK CLOSED MONITOR:  At ignition off, the state of the ESIM Switch is evaluated. If the switch is open, a pass flag will set so the PCM power down process can complete. If the switch is closed, the PCM will wait a calibrated delay time and open the Purge Solenoid. In a normally functioning system, this will relieve the vacuum trapped in the Charcoal Canister allowing the switch to open. When the switch opens, a pass flag is set and the PCM will power down. If the ESIM switch does not open, after a calibrated time, an error is detected and a switch stuck closed failure event is set (P0452)  . Two consecutive failed events will mature a fault. The Switch stuck closed fault can set because of an electrical or mechanical issue. The electrical failures could be a short low in the ESIM signal or the switch is stuck closed inside the ESIM. NOTE: An open signal would cause it to be high and never read closed which would set one of the leak faults.  The mechanical failures could be a blockage somewhere in the purge circuit that is not allowing vacuum to be relieved when the Purge Solenoid is energized. The best way to diagnose the issue is to first determine if the issue is due to an electrical issue or mechanical issue (blockage).

Diagnosing the system for an electrical or mechanical issue: 

• First, remove the Fuel Cap or open the Capless fuel filler using a funnel while monitoring the ESIM Switch state. If the switch state changes to open, the likely cause is a blockage in the Purge Tube, Manifold Tube, intake port, or a faulty Purge Solenoid that is not opening. The reason the switch was able to open when removing the Fuel Cap or opening the capless fuel filler is because this is a different path to atmosphere than the system uses during the diagnostic (refer to the generic graphic below). This also proves that the ESIM Switch is not stuck closed and the signal is not shorted.
• If the ESIM Switch stayed closed when vented it is likely due to a stuck switch or signal circuit shorted low. If the vehicle is equipped with a Fuel Tank Pressure Sensor, monitoring the sensor reading can confirm the system vacuum was relieved. The Fuel Tank pressure should read near 0 Pa with the system vented.
• Monitor the ESIM Switch state and disconnect the ESIM harness connector. Try not to disturb the wiring harness so that you don't incidentally disturb a wiring issue. If the switch state changes to open when unplugged, a wiring issue can likely be ruled out since an open signal circuit should cause the switch state to change to open. If the switch state still reads closed with the ESIM connector unplugged the signal circuit is shorted low.

Courtesy of CHRYSLER GROUP, LLC