Pinpoint Test F: DTC P1635
Four Wheel Drive (4WD) Systems
Pinpoint Tests
Pinpoint Test F: DTC P1635
Refer to Wiring Diagram Set 34 (Fusion/Milan/MKZ, Fusion Hybrid/Milan Hybrid), All Wheel Drive (AWD) for schematic and connector information. Diagrams By Number
Normal Operation
The All-Wheel Drive (AWD) system continuously monitors vehicle conditions and automatically adjusts the torque distribution between the front and rear wheels. During normal operation, most of the torque is sent to the front wheels. If wheel slip between the front and rear wheels is detected or the vehicle is under heavy acceleration, the AWD system increases torque to the rear wheels.
- DTC P1635 Tire/Axle Out of Acceptable Range - When the 4X4 control module detects inappropriate mini spare or road wheels/tires (greater than 7% across the front and rear axle or 14% at one wheel) installed, this DTC is set.
This pinpoint test is intended to diagnose the following:
- Wheels/tires
- Wheel speed sensors
- ABS module
- 4X4 control module
PINPOINT TEST F: DTC P1635
WARNING: When directed to drive the vehicle as part of this test, drive the vehicle on a hard surface in an area without traffic to prevent a crash. Failure to follow these instructions may result in personal injury.
NOTE: Carry out a thorough inspection and verification as outlined before carrying out this pinpoint test. Inspection and Verification
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F1 CHECK THE RECENT TIRE USAGE
- Check with customer about recent tire usage or installation.
- Has a tire been installed on the vehicle recently that was not originally supplied with the vehicle?
Yes
INFORM the customer to only use tires of the type supplied with the vehicle. CLEAR the DTCs. REPEAT the self-test.
No
GO to F2.
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F2 CHECK TIRE SIZE AND BRAND
- Check the tire size and the brand of tire.
- Are all 4 tires the same size and brand?
Yes
GO to F3.
No
INSTALL tires that are the same size and brand. INFORM the customer to only use the same size tires and brand. CLEAR the DTCs. REPEAT the self-test.
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F3 CHECK TIRE AIR PRESSURES
- Check the air pressure in all 4 tires.
- Are all 4 tires at the recommended air pressure?
Yes
GO to F4.
No
ADJUST the tire air pressures. CLEAR the DTCs. REPEAT the self-test. INFORM the customer to maintain the correct tire air pressure.
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F4 CHECK FOR CORRECT WHEEL SPEEDS
- Connect the scan tool.
- Enter the following diagnostic mode on the scan tool: DataLogger - 4X4 Control Module .
- While driving the vehicle at 48 km/h (30 mph), monitor the following wheel speed sensor PIDs:
- Left Front Wheel Speed Sensor (LF_WSPD)
- Left Rear Wheel Speed Sensor (LR_WSPD)
- Right Front Wheel Speed Sensor (RF_WSPD)
- Right Rear Wheel Speed Sensor (RR_WSPD)
- Are all 4 wheel speeds within 2 km/h (1.2 mph) of each other?
Yes
GO to F5.
No
The ABS module is sending invalid wheel speed data to the 4X4 control module. REFER to Antilock Brakes / Traction Control Systems for additional ABS diagnosis.
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F5 CHECK FOR CORRECT 4X4 CONTROL MODULE OPERATION
- Disconnect: 4X4 Control Module C3253 .
- Check for:
- corrosion.
- pushed-out pins.
- Connect the 4X4 control module and make sure it seats correctly.
- Operate the system and determine if the concern is still present.
- Is the concern still present?
Yes
INSTALL a new 4X4 control module. REFER to 4X4 Control Module Service and Repair. CLEAR the DTCs. REPEAT the self-test.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the self-test.
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