Pinpoint Test G: No Communication With The 4X4 Module

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.

CAUTION: Use the Flex Probe Kit for all test connections to prevent damage to the wiring terminals. Do not use standard multimeter probes.

G1 CHECK FOR DIAGNOSTIC TOOL COMMUNICATION WITH THE 4X4 MODULE
- Verify diagnostic tool communication with the vehicle 4WD control module.
  - If using the WDS, follow the directions and carry out the network test.
  - If using NGS+, verify that the vehicle and engine selection information is correct.
- WDS: Does the network test pass for the 4WD control module?
Yes : REFER to the appropriate diagnostic tool's manual for further diagnosis.

No : GO to G2.

G2 CHECK IGNITION SWITCH STATUS PID

Key in ON position.

Monitor the ignition switch status PID.

IGNITION SWITCH POSITION CHART

Ignition Switch Position	PID	Expected Value
OFF	IGN_O/L	OFF
ACCESSORY	IGN_ACC	ACCY
RUN	IGN_R	RUN
START	IGN_S	START

Do the ignition switch PIDs match the ignition switch positions?

Yes : GO to G3.

No : CHECK the ignition switch. REFER to STARTING SYSTEM - GASOLINE ENGINES for gasoline engines or STARTING SYSTEM - DIESEL ENGINE for diesel engines. After the fault is repaired, CLEAR the DTC. REPEAT the self-test.

G3 CHECK FOR VOLTAGE INPUT TO THE 4X4 MODULE (GEM)

Disconnect: 4WD Control Module C281a.
Key in ON position.

Measure the voltage between 4WD control module C281a and ground as follows:

PINOUTS REFERENCE

C281a Pin	Circuit
1	1306 (PK/WH)
2	1306 (PK/WH)
5	640 (RD/YE)
6	1002 (BK/PK)

Fig 1: Checking For Voltage Input To 4X4 Module (GEM)

Courtesy of FORD MOTOR CO.

Are the voltages at each pin greater than 9 volts?

Yes : GO to G7.

No : GO to G4.

G4 CHECK THE CENTRAL JUNCTION BOX (CJB) MINI-FUSES
- Check CJB mini-fuses:
  - 19 (10A).
  - 45 (10A).
  - 33 (15A).
- Are the fuses okay?
Yes : GO to G5.

No : INSTALL new fuses. REPAIR the circuits as necessary. REPEAT the self-test.
G5 CHECK FOR BATTERY VOLTAGE AT THE BJB AND CJB POWER INPUT FUSE CAVITIES
- Key in ON position.
- Measure the voltage between CJB input side fuse cavities and ground:
  - 19 (10A).
  - 45 (10A).
  - 33 (15A).
- Are the voltages greater than 9 volts?
Yes : GO to G7.

No : GO to G6.
G6 CHECK THE BATTERY VOLTAGE WITH THE ENGINE RUNNING
- Start the engine.
- Measure the battery voltage at the positive battery terminal.
- Is the voltage greater than 9 volts?
Yes : GO to G7.

No : CHECK the charging system. REFER to CHARGING SYSTEM - GENERAL INFORMATION .
G7 CHECK THE GROUND CIRCUIT FOR AN OPEN
- Disconnect the battery ground cable. Refer to CHARGING SYSTEM - GENERAL INFORMATION
- Disconnect: 4WD control module (GEM) C281a.
- Measure the resistance between C281a-3, circuit 57 (BK) and ground.
  
  Fig 2: Checking Ground Circuit For Open
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
Yes : GO to G8.

No : REPAIR the circuit. REPEAT the self-test.
G8 CHECK FOR A FLOATING GROUND
- Measure the voltage between C281a-3, circuit 57 (BK) and ground.
  
  Fig 3: Checking For Floating Ground
  Courtesy of FORD MOTOR CO.
- Is voltage (greater than 1V) present?
Yes : REPAIR the circuit. REPEAT the self-test.

No : GO to G9.
G9 CHECK THE 4X4 MODULE CONNECTOR
- Disconnect the 4WD control module (GEM) connectors C281a and C281b.
- CHECK for corrosion and/or pushed out pins.
- Is the connector corroded and/or damaged?
Yes : REPAIR or CLEAN the connector(s) as necessary. Reconnect and 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.