Pinpoint Test I: DTC B2172 - Inertia Fuel Shutoff (IFS) Switch Input Circuit Open
High-Voltage Traction Battery
Pinpoint Tests
Pinpoint Test I: DTC B2172 - Inertia Fuel Shutoff (IFS) Switch Input Circuit Open
Refer to Wiring Diagram Set 12 (Escape/Mariner, Escape Hybrid/Mariner Hybrid), Charging System for schematic and connector information. Diagrams By Number
Normal Operation
With the engine running, the battery power off (BPO) function may be triggered by the Inertia Fuel Shutoff (IFS) switch or the High Voltage Cut Off Switch opening, a high-voltage interlock circuit opening, the electrical interlock (EL I) circuit opening (fuse protected by the Battery Junction Box (BJB) fuse 26 [20A]) or if the contactor box within the Battery Control Module - High Voltage Traction Battery (BCM-HVTB) requests a BPO mode. If the IFS switch opens and causes the BPO mode to occur and DTCs are set. Also, if the IFS switch is open, a power reset indicator in the Instrument Cluster (IC) illuminates. With the ignition switch in the ON position and the engine ON or OFF (the engine must have run at least once after the key was cycled to ON), the BCM-HVTB monitors the contactors continuously. During a power down (key OFF) sequence, one or both of the contactors may set this DTC if they fail.
- DTC B2172 (IFS Switch Input Circuit Open) - If the BCM detects that the IFS switch circuit(s) is open, the DTC is set.
This pinpoint test is intended to diagnose the following:
- IFS switches
- Circuitry
- High Voltage Traction Battery (HVTB)
PINPOINT TEST I: DTC B2172 - INERTIA FUEL SHUTOFF (IFS) SWITCH INPUT CIRCUIT OPEN
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I1 CHECK THE IFS SWITCH AND THE HIGH VOLTAGE CUT OFF SWITCH
- NOTE: The IFS switch is located on the RH kick panel and the High Voltage Cut Off Switch is located near the RH rear tail lamp behind the jack.
- Check the IFS switch and the High Voltage Cut Off Switch, verify that the reset buttons on the top of the switches are pushed (closed).
- Are the switch reset buttons closed?
Yes
GO to I2.
No
INSTALL a new switch as necessary. CLEAR the DTC. REPEAT the self-test. TEST the system for normal operation. If DTC B2172 is still present GO to I2.
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I2 CHECK THE IFS SWITCH POWER INPUT CIRCUITS
- Ignition OFF.
- Disconnect: Battery Control Module - High Voltage Traction Battery (BCM-HVTB) C4227a.
- Ignition ON.
- Measure the voltage between ground and:
- BCM-HVTB C4227a-7 , circuit CYB15 (GN), harness side.
- BCM-HVTB C4227a-23, circuit CYB15 (GN), harness side.
- Is the voltage greater than 10 volts at C4227a-7 and C4227a-23?
Yes
GO to I7.
No
If there is no voltage at either pin GO to I3. If voltage is available at one pin only. REPAIR circuit CYB15 (GN) and TEST the system for normal operation.
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I3 CHECK THE HIGH VOLTAGE CUT OFF SWITCH POWER INPUT CIRCUITS
- Ignition OFF.
- Disconnect: High Voltage Cut Off Switch C4229.
- Ignition ON.
- Measure the voltage between the high voltage cut off switch C4229-2, circuit CE911(VT/WH), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to I5.
No
GO to I4.
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I4 CHECK THE IFS SWITCH SUPPLY CIRCUIT
- Ignition OFF.
- Disconnect: IFS Switch C392.
- Measure the voltage between the IFS switch C392-2, circuit CBB26 (BU/WH), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to I6.
No
VERIFY the BJB fuse 26 (20A). If the fuse is OK. REPAIR the open in circuit CBB26 (BU/WH). If the fuse is not OK. Refer to Wiring Diagrams to identify the short to ground. Diagrams By Number
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I5 CHECK THE REAR HIGH VOLTAGE CUT OFF SWITCH RESISTANCE
- Measure the resistance between the high voltage cut off switch C4229-1, component side and the high voltage cut off switch C4229-2, component side.
- Is the resistance less than 5 ohms?
Yes
REPAIR the open in circuit CYB15 (GN). CLEAR the DTCs and TEST the system for normal operation.
No
INSTALL a new high voltage cut off switch. CLEAR the DTCs and TEST the system for normal operation.
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I6 CHECK THE IFS SWITCH RESISTANCE
- Measure the resistance between the IFS switch C392-2, component side and the IFS switch C392-1, component side.
- Is the resistance less than 5 ohms?
Yes
REPAIR the open in circuit CE911 (VT/WH). CLEAR the DTCs and TEST the system for normal operation.
No
INSTALL a new IFS switch. CLEAR the DTCs and TEST the system for normal operation.
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I7 CHECK THE BCM-HVTB GROUND CIRCUIT
- Measure the voltage between BCM-HVTB C4227a-7 circuit CYB15 (GN) harness side and:
- BCM-HVTB C4227a-30 circuit GD182 (BK/GY) harness side.
- BCM-HVTB C4227a-31 circuit GD182 (BK/GY) harness side.
- Are the voltages at least 10 volts?
Yes
GO to I8.
No
REPAIR circuit GD182 (BK/GY). CLEAR the DTC. TEST the system for normal operation.
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I8 CHECK RETURNING DTCs
- Ignition OFF.
- Connect: BCM-HVTB C4227a.
- Connect the scan tool.
- Ignition ON.
- Using the scan tool, clear all BCM-HVTB DTCs.
- Enter the following diagnostic mode on the scan tool: Self Test - BCM-HVTB.
- Is DTC B2172 present?
Yes
INSTALL a new BCM-HVTB. REFER to High-Voltage Traction Battery Service and Repair. TEST the system for normal operation.
No
The system is operating correctly at this time. The concern may have been caused by a poor or intermittent connection.
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