S2508000056 Service Bulletin/Repair Instructions

Case Number: S2508000056

Release Date: July 2025

Symptom/Vehicle Issue: 12v Ignition Off Draw (IOD) Caused By Power Electronics

Coolant Pump 1 (PECP-1) Continuously Running When Vehicle Is Asleep

Discussion: The vehicle may come in with a depleted 12v battery. Upon charging the

battery and performing IOD testing, three minutes after the ignition is switched OFF

you may find a 16A+ draw and hear the Power Electronics Coolant Pump 1 (PECP-1)

running at full speed continuously.

The PECP-1 is controlled over LIN 2 (Circuit D548) by the Electric Vehicle Control Unit

(EVCU). If the PECP-1 is woken up and does not receive a message from the LIN

Master (EVCU), it goes into “Emergency Mode” and defaults to running at 100% pump

speed creating a 16A+ draw.

While this can occur anytime the EVCU is not communicating with the pump, most

commonly observed while performing flashes. Engineering has found that a

malfunctioning component on LIN 2 (D548) can inadvertently provide a pull-down

wakeup command which will awaken PECP-1 when the ignition and EVCU are OFF.

Because the EVCU is OFF and not communicating with PECP-1 when this occurs, it

goes into “Emergency Mode” and operates at full speed. Follow diagnostics steps

below to determine root cause of inadvertent LIN wakeup.
This document does not authorize warranty repairs. This communication documents a record of past experiences. STAR Online

does not provide any conclusions about what is wrong with the vehicle. Rather, it captures all previous cases known that appear

to be similar or related to the vehicle symptom / condition. You are the expert, and you are responsible for deciding on the

appropriate course of action.
Contact STAR Center, or your Technical Assistance Center Via TechConnect, eCONTACT or Service Library

entry if no solution is found.

Stellantis US LLC
Version 4.5 07/22/2022
Diagnostics: To determine if this issue is applicable to the vehicle you are working on,

perform and monitor the following:

1.

2.

3.

4.
Disconnect wiTECH to allow vehicle to go to sleep.

Locate PECP-1 (Use reference images on pages below)

Cycle the ignition OFF. Vehicle should begin going into sleep mode.

Two minutes after the ignition is switched OFF, the High Voltage contactors will

open.

5. 1 minute following opening of the contactors the EVCU will issue a LIN bus sleep

command, and all pumps will shut off.

6. Approximately 0.4-0.5 seconds after the LIN bus sleep command is given and all

the pumps have shut down you will hear PECP-1 turn back on and run at full

speed.

In summary, if this issue applies PECP-1 should begin running at full speed

approximately 3 minutes after the ignition is switched off and will create a 16+

Amp IOD.

7. Engineering has found that the most common component triggering this

unintentional wakeup command is a malfunctioning Electronic A/C Compressor

(EAC). Disconnect the low voltage 3 way connector (C1) from the EAC to isolate

it from the LIN bus and repeat steps 1-6 above.

7.1 Does PECP-1 continue to run at full speed 3 minutes after the ignition

is switched off?

YES – Further diagnostics are required. Continue to step 8.

NO – Confirm circuit integrity of the EAC including all power and grounds. If

no trouble found, replace the EAC. After replacement, confirm repair of

IOD.

This document does not authorize warranty repairs. This communication documents a record of past experiences. STAR Online

does not provide any conclusions about what is wrong with the vehicle. Rather, it captures all previous cases known that appear

to be similar or related to the vehicle symptom / condition. You are the expert, and you are responsible for deciding on the

appropriate course of action.
Contact STAR Center, or your Technical Assistance Center Via TechConnect, eCONTACT or Service Library

entry if no solution is found.

Stellantis US LLC
Version 4.5 07/22/2022
8. Connect an Oscilloscope to monitor and continuously record LIN 2 (D548). Cycle

the ignition off, after approximately 3 minutes monitor the LIN bus for an

unintentional wakeup command. A LIN bus wakeup command is defined as a

voltage pull down which is greater than 50% of B+ voltage.
The example above shows a normal view (top) and zoomed in view (bottom) of the

same unintentional LIN wake up command, dropping from 11.6v to 5.15v. This

unintended wakeup command is only 5 milliseconds or 0.005 seconds long. Reviewing

the recording will be necessary to identify.

If you observe the LIN wakeup command occurring after cycling the ignition OFF

causing PECP-1 to run and no change when disconnecting the EAC. You will need to

individually disconnect each component from LIN 2 to identify which one is providing

the unintentional wake up command. Besides the EAC, the Auxiliary High Temperature

Heat Pump is the other most likely cause as it is provided B+ at all times. Though

malfunction of the Low Temp Expansion Valve, EVCU and wiring are also a possibility.

This document does not authorize warranty repairs. This communication documents a record of past experiences. STAR Online

does not provide any conclusions about what is wrong with the vehicle. Rather, it captures all previous cases known that appear

to be similar or related to the vehicle symptom / condition. You are the expert, and you are responsible for deciding on the

appropriate course of action.
Contact STAR Center, or your Technical Assistance Center Via TechConnect, eCONTACT or Service Library

entry if no solution is found.

Stellantis US LLC
Version 4.5 07/22/2022
EVCU
Diagram of LIN 2
This document does not authorize warranty repairs. This communication documents a record of past experiences. STAR Online

does not provide any conclusions about what is wrong with the vehicle. Rather, it captures all previous cases known that appear

to be similar or related to the vehicle symptom / condition. You are the expert, and you are responsible for deciding on the

appropriate course of action.
Contact STAR Center, or your Technical Assistance Center Via TechConnect, eCONTACT or Service Library

entry if no solution is found.

Stellantis US LLC
Version 4.5 07/22/2022
LB – PECP-1 Located Under Hood Front of Drivers Wheel Well
Pump-Power Electronics Coolant 1
KM – PECP-1 Located Under Hood Lower on Front of Drivers Frame Horn
This document does not authorize warranty repairs. This communication documents a record of past experiences. STAR Online

does not provide any conclusions about what is wrong with the vehicle. Rather, it captures all previous cases known that appear

to be similar or related to the vehicle symptom / condition. You are the expert, and you are responsible for deciding on the

appropriate course of action.
Contact STAR Center, or your Technical Assistance Center Via TechConnect, eCONTACT or Service Library

entry if no solution is found.

Stellantis US LLC
Version 4.5 07/22/2022
Pictured above you can see the coolant pump assembly with three induvial pumps.

They communicate with the EVCU on three separate LIN buses. While these pumps

are all keyed and physically the same, each pump has a unique part number and

contains unique software for identification over their respective LIN bus. The circuit

color for Power, Ground and LIN are identical across all three pumps. PECP-1 and

BCP have the same square symbol. While PECP-2 has a triangle symbol. Engineering

is planning to make these symbols unique for easier identification (no ETA). By

referencing the above image and noting the location of the pumps on the assembly

bracket, you should be able to identify the location of PECP-1 on vehicle.

This document does not authorize warranty repairs. This communication documents a record of past experiences. STAR Online

does not provide any conclusions about what is wrong with the vehicle. Rather, it captures all previous cases known that appear

to be similar or related to the vehicle symptom / condition. You are the expert, and you are responsible for deciding on the

appropriate course of action.
Contact STAR Center, or your Technical Assistance Center Via TechConnect, eCONTACT or Service Library

entry if no solution is found.

Stellantis US LLC
Version 4.5 07/22/2022

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