Pinpoint Test Q: DTC P189B:00
Four Wheel Drive (4WD) Systems - Electronic Shift
Pinpoint Tests
Pinpoint Test Q: DTC P189B:00
Refer to Wiring Diagram Set 34, Four-Wheel Drive Systems for schematic and connector information. Diagrams By Number
NOTE: Place the Mode Select Switch (MSS) in 2H prior to carrying out a self-test of the Transfer Case Control Module (TCCM). This will disable the Electronic Locking Differential (ELD) field coil.
NOTE: Make sure the battery is fully charged before performing this pinpoint test.
Normal Operation
The vehicle must be engaged into either 4H or 4L (and in 2H on SVT Raptor only) mode in order to operate the rear ELD. When the MSS is engaged to lock the rear differential, a Pulse Width Modulated (PWM) signal is sent to the ELD field coil by the TCCM through circuit CCF31. This signal is a PWM signal which is initially 98% duty cycle to lock the differential and decreases to 40% duty cycle once the differential is locked. When the differential is starting to lock, the indicator on the MSS will start to blink. When the differential is fully locked, the indicator will illuminate steady.
- DTC P189B:00 (Axle Disconnect Input Switch Circuit High: No Sub Type Information) - When not in locking mode, the TCCM senses whether the ELD mode switch circuit has high voltage and if the differential is always engaged. This DTC will not set unless the MSS is set to 2H. If the MSS is functioning normally, the differential will immediately lock when the MSS is set to 4H or 4L. This DTC will only display during the self-test function.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- TCCM
PINPOINT TEST Q: DTC P189B:00
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Q1 CHECK FOR A SHORT ON THE LOCKER MODE SWITCH CIRCUIT
- Ignition OFF.
- Disconnect: TCCM C2371A.
- Ignition ON.
- With the MSS in 2H, measure the voltage between TCCM C2371A-15, circuit CCF32 (WH/GN), harness side and ground.
- Is any voltage present?
Yes
GO to Q2.
No
GO to Q3.
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Q2 ISOLATE THE MSS DISCONNECTED
- Ignition OFF.
- Disconnect: MSS C284.
- Ignition ON.
- Measure the voltage at TCCM C2371A-15, circuit CCF32 (WH/GN), harness side and ground.
- Is any voltage present?
Yes
REPAIR circuit CCF32 (WH/GN). CLEAR the DTCs. TEST the system for normal operation. REPEAT the self-test.
No
INSTALL a new MSS. REFER to Mode Select Switch (MSS) Service and Repair. TEST the system for normal operation.
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Q3 CHECK FOR CORRECT TCCM OPERATION
- Ignition OFF.
- Disconnect all TCCM connectors.
- Check for:
- corrosion.
- pushed-out pins.
- Connect all TCCM connectors and make sure they are seated correctly.
- Operate the system and verify the concern is still present.
- Is the concern still present?
Yes
INSTALL a new TCCM. REFER to Transfer Case Control Module (TCCM) Service and Repair. TEST the system for normal operation. REPEAT the self-test.
No
The system is operating correctly at this time. Concern may have been caused by a loose or corroded connector. CLEAR the DTCs. TEST the system for normal operation. REPEAT the self-test.
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