Pinpoint Test K: The Transfer Case Does Not Shift Between 4X4 High and 4X4 Low Modes Correctly

Four Wheel Drive (4WD) Systems - Electronic Shift

Pinpoint Tests

Pinpoint Test K: The Transfer Case Does Not Shift Between 4X4 High and 4X4 Low Modes Correctly

Normal Operation

The high/low shift occurs when the reduction shift fork moves the high/low collar to lock the planetary gear set to the output shaft. The torque transmitted through the sun gear from the input shaft turns the front planetary gear set assembly. The front planetary gear set assembly, now engaged, provides transfer case speed reduction. Certain criteria, such as vehicle speed and Transmission Range (TR) selection, must be met before this shift can occur.

- DTC C1729 (Transfer Case Unable to Transition Between 4H and 4L) - Fault sets when target shift motor position is not reached after the maximum number of allowed blocked shift retries for 4H to 4L or 4L to 4H. Requested shift motor position is not reached.
- DTC P0500 (Vehicle Speed Sensor (VSS) Malfunction) - Fault sets when insufficient VSS input from the ABS through the Controller Area Network (CAN). The PCM detects a loss of VSS signal and sets this DTC.
- DTC P1819 (Transmission Neutral Safety Switch Short Circuit To Ground) - Fault sets when the 4X4 control module senses the neutral safety switch is shorted to ground. When this occurs the 4X4 control module cannot verify the vehicle has moved out of the Park/Neutral position.

This pinpoint test is intended to diagnose the following:
- Transmission neutral switch (or Clutch Pedal Position (CPP) switch) - hardwired to the 4X4 control module
- ABS vehicle speed inputs - hardwired to the 4X4 control module

PINPOINT TEST K: THE TRANSFER CASE DOES NOT SHIFT BETWEEN 4X4 HIGH AND 4X4 LOW MODES CORRECTLY

NOTICE: Use the Flex Probe Kit for all test connections to prevent damage to the wiring terminals. Do not use standard multi-meter probes.

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K1 CHECK THE 2WD HIGH TO 4WD HIGH (4X4 HIGH) SHIFT

- Drive the vehicle and shift the Mode Select Switch (MSS) from 2-Wheel Drive (2WD) to 4X4 High while rolling.
- Does the vehicle shift between 2WD and 4X4 High correctly?

Yes
GO to K2.

No
GO to Pinpoint Test L. Pinpoint Test L: Four-Wheel Drive (4WD) Does Not Engage At Speed Correctly

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K2 CHECK THE 4X4 HIGH TO 4X4 LOW SHIFT

- Bring the vehicle to a speed below 8 km/h (5 mph). With the transmission in NEUTRAL (or clutch applied), switch the MSS to 4X4 Low.
- Does the transfer case shift from 4X4 High to 4X4 Low correctly and the concern is related to a clunk noise during the shift?

Yes
Transmission neutral drag torque is excessive. REFER to Automatic Transmission/Transaxle &/or Transmission Control Systems for transmission diagnosis.

No
GO to K3.

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K3 CHECK THE TRANSMISSION RANGE TR AND VEHICLE SPEED PIDs

- Connect the scan tool.
- A. Monitor the 4X4 control module Neutral Safety Switch (NSAFETYSW) PID while shifting the transmission through gear ranges (or while applying the clutch).
- B. Monitor the vehicle speed PID with the vehicle at rest.
- A. Does the 4X4 control module transmission neutral PID indicate NEUTRAL when the transmission is shifted to NEUTRAL (or when the clutch pedal is applied)?

B. Does the vehicle speed PID indicate 0 km/h (0 mph)?

Yes
If both PIDs are accurate, GO to Pinpoint Test N. Pinpoint Test N: Straightline Driveline Wind Up

No
A. If equipped with gasoline automatic transmissions, GO to K4.

If equipped with diesel manual transmissions, GO to K7.

If equipped with diesel automatic transmissions, GO to K10.

B. REFER to Antilock Brakes / Traction Control Systems for further diagnosis of the ABS system.

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K4 CHECK THE NEUTRAL SAFETY SWITCH STATUS (NSAFETYSW) PID

- Enter the following diagnostic mode on the scan tool: DataLogger - 4X4 Control Module.
- Monitor the NSAFETYSW PID.
- Does the NSAFETYSW PID indicate NEUTRAL when the transmission is shifted to NEUTRAL?

Yes
GO to K5.

No
REFER to Automatic Transmission/Transaxle &/or Transmission Control Systems for further diagnosis of the TR sensor.

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K5 CHECK CIRCUIT CET21 (GN/WH) FOR A SHORT TO GROUND

- Ignition OFF.
- Disconnect: PCM C175B.
- Measure the resistance between PCM C175B-22, circuit CET21 (GN/WH), harness side and ground.

- Is the resistance greater than 10,000 ohms?

Yes
GO to K6.

No
REPAIR circuit CET21 (GN/WH). CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.

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K6 CHECK CIRCUIT CET21 (GN/WH) FOR AN OPEN

- Disconnect: 4X4 Control Module C281A.
- Measure the resistance between 4X4 control module C281A-4, circuit CET21 (GN/WH), harness side and PCM C175B-22, circuit CET21 (GN/WH) harness side.

- Are the resistances less than 5 ohms?

Yes
GO to Pinpoint Test N. Pinpoint Test N: Straightline Driveline Wind Up

No
REPAIR circuit CET21 (GN/WH). CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.

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K7 CHECK GROUND CIRCUIT GD113 (BK/YE)

- Disconnect: CPP Switch C257.
- Measure the resistance between CPP switch C257-6, circuit GD113 (BK/YE) harness side and ground.

- Are the resistances less than 5 ohms?

Yes
GO to K8.

No
REPAIR circuit GD113 (BK/YE). CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.

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K8 CHECK THE CIRCUIT CET21 (GN/WH) FOR AN OPEN

- Disconnect: 4X4 Control Module C281A.
- Measure the resistance between 4X4 control module C281A-4, circuit CET21 (GN/WH) harness side and CPP switch C257-5, circuit CET21 (GN/WH) harness side.

- Are the resistances less than 5 ohms?

Yes
GO to K9.

No
REPAIR circuit CET21 (GN/WH). CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.

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K9 CHECK THE CPP SWITCH

- Measure the resistance between CPP switch pins 5 and 6 side while applying the clutch pedal.

- Are the resistances less than 5 ohms?

Yes
REPLACE the 4X4 control module. REFER to 4X4 Control Module Service and Repair. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.

No
REPLACE the CPP switch. CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.

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K10 CHECK THE NEUTRAL SAFETY SWITCH STATUS (NSAFETYSW) PID

- Enter the following diagnostic mode on the scan tool: DataLogger - 4X4 Control Module.
- Monitor the NSAFETYSW PID.
- Does the NSAFETYSW PID indicate NEUTRAL when the transmission is shifted to NEUTRAL?

Yes
GO to K11.

No
REFER to Automatic Transmission/Transaxle &/or Transmission Control Systems for further diagnosis of the TR sensor.

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K11 CHECK CIRCUIT CET21 (GN/WH) FOR A SHORT TO GROUND

- Ignition OFF.
- Disconnect: TCM C1750.
- Measure the resistance between TCM C1750-30, circuit CET21 (GN/WH), harness side and ground.

- Is the resistance greater than 10,000 ohms?

Yes
GO to K12.

No
REPAIR circuit CET21 (GN/WH). CLEAR the DTCs. REPEAT the self-test. TEST the system for normal operation.

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K12 CHECK CIRCUIT CET21 (GN/WH) FOR AN OPEN

- Disconnect: 4X4 Control Module C281A.
- Measure the resistance between 4X4 control module C281A-4, circuit CET21 (GN/WH), harness side and TCM C1750-30, circuit CET21 (GN/WH) harness side.