Pinpoint Test Q: Transmission 4-Wheel Drive Mode Select Switch Failure

WARNING: This page is about a different car, the 2006 Ford Pickup, 2006 Ford F550 Super Duty, 2006 Ford F450 Super Duty, and 2006 Ford Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.

Q1 CHECK THE MSS PIDS
- Connect the scan tool.
- Key in ON position.
- Monitor each 4WD__SW PID while cycling through each MSS position.
- Does each MSS PID agree with each switch position?
Yes : No problem found. CLEAR the DTCs. GO to PINPOINT TEST P .

No : GO to Q2.

Q2 CHECK MSS RESISTANCE VALUES

Key in OFF position.
Disconnect: MSS C284.

Measure the resistance between MSS C284-, terminals 2 and 3, component side, while rotating the switch through all positions. Refer to the following chart:

RESISTANCE REFERENCE CHART

Mode Select Switch (MSS) Position Resistance
4L	4H	2H
130 ohms	270 ohms	619 ohms

Fig 1: Checking MSS Resistance Values

Courtesy of FORD MOTOR CO.

Are the resistance values within specification?

Yes : GO to Q3.

No : INSTALL a new MSS. REFER to MODE SELECT SWITCH (MSS) . CLEAR the DTCs. REPEAT the self-test.

Q3 CHECK MSS CIRCUITS 465 (WH/LB) AND 780 (DB) FOR SHORT TO GROUND
- Key in OFF position.
- Disconnect: 4WD Control Module, (GEM) C281b.
- Disconnect: MSS C284.
- Measure the resistance between MSS C284-2, circuit 465 (WH/LB) harness side and ground.
- Measure the resistance between MSS C284-3, circuit 780 (DB) harness side and ground.
  
  Fig 2: Checking MSS Circuits 465 (WH/LB) And 780 (DB) For Short To Ground
  Courtesy of FORD MOTOR CO.
- Is the resistance greater than 10,000 ohms?
Yes : GO to Q4.

No : REPAIR the affected circuit(s). CLEAR the DTCs. REPEAT the self-test.
Q4 CHECK MSS CIRCUITS 465 (WH/LB) AND 780 (DB) FOR AN OPEN
- Key in OFF position.
- Disconnect: 4x4 Module (GEM) C281b.
- Measure the resistance between MSS C284-2 and 4WD control module (GEM) C281b-9, circuit 465 (WH/LB).
- Measure the resistance between MSS C284-3 and 4WD control module (GEM) C281b-2, circuit 780 (DB).
  
  Fig 3: Checking MSS Circuits 465 (WH/LB) And 780 (DB) For Open
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
Yes : GO to Q5.

No : REPAIR the affected circuit(s). CONNECT the 4WD control module (GEM). CLEAR the DTCs. REPEAT the self-test.
Q5 CHECK MSS CIRCUITS 465 (WH/LB) AND 780 (DB) FOR SHORT TOGETHER
- Key in OFF position.
- Measure the resistance between MSS C284-2, circuit 465 (WH/LB) harness side and C284-3, circuit 780 (DB).
  
  Fig 4: Checking MSS Circuits 465 (WH/LB) And 780 (DB) For Short Together
  Courtesy of FORD MOTOR CO.
- Is the resistance greater than 10,000 ohms?
Yes : GO to Q6.

No : REPAIR the circuits. CLEAR the DTC. REPEAT the self-test.
Q6 CHECK MSS CIRCUITS 465 (WH/LB) AND 780 (DB) FOR A SHORT TO BATTERY
- Key in ON position.
- Disconnect: 4WD Control Module (GEM) C281b.
- Measure the voltage between MSS C284-2, circuit 465 (WH/LB) harness side and ground.
- Measure the voltage between MSS C284-3, circuit 780 (DB) harness side and ground.
  
  Fig 5: Checking MSS Circuits 465 (WH/LB) And 780 (DB) For Short To Battery
  Courtesy of FORD MOTOR CO.
- Is voltage present?
Yes : REPAIR the circuit(s). CLEAR the DTC. REPEAT the self-test.

No : GO to Q7.
Q7 CHECK MSS CIRCUIT 780 (DB) FOR REFERENCE VOLTAGE
- Connect: 4x4 Module (GEM) C281b.
- Key in ON position.
- Measure the voltage between MSS C284-3, circuit 780 (DB) harness side and ground.
  
  Fig 6: Checking MSS Circuit 780 (DB) For Reference Voltage
  Courtesy of FORD MOTOR CO.
- Is a +5-volt reference present (not battery voltage)?
Yes : No problem found. The condition may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the self-test.

No : INSTALL a new 4WD control module (GEM). REFER to FOUR WHEEL DRIVE (4WD) CONTROL MODULE . TEST the system for normal operation.