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Possible Causes

Power supply circuit (G/R)
Smart junction box (SJB) fuse 28 (15A)
Ground circuit (B/W)
Charging system
Battery

CAUTION:

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

NO COMMUNICATION WITH 4WD CONTROL MODULE - PINPOINT TEST REFERENCE

PINPOINT TEST 1		NO COMMUNICATION WITH THE 4WD CONTROL MODULE
STEP	INSPECTION		ACTION
1	CHECK FOR SCAN TOOL COMMUNICATION WITH THE VEHICLE Verify scan tool communication with the vehicle. Does the scan tool communicate with the PCM?	Yes	Go to next step.
1		No	REFER to the appropriate scan tool manual for further diagnosis.
2	CHECK FOR VOLTAGE INPUT TO THE 4WD CONTROL MODULE Disconnect 4WD Control Module 0318-03 Measure the voltage between 0318-03 pin 7, circuit (G/R) and ground. Is the voltage greater than 9 volts?	Yes	Go to step 6.
2		No	Go to next step.
3	CHECK THE SMART JUNCTION BOX (SJB) FUSE Check the smart junction box (SJB) fuse 28(15A). Is the fuse OK?	Yes	Go to next step.
3		No	CHECK circuit (G/R) for a short to ground or open. REPAIR as necessary. REPEAT the self-test.
4	CHECK FOR BATTERY VOLTAGE FROM THE SMART JUNCTION BOX (SJB) Key ON, engine OFF (KOEO) Measure the voltage between smart junction box SJB input side fuse cavity 28 and ground. Is the voltage greater than 9 volts?	Yes	REPAIR or INSTALL new components as necessary. REPEAT the self-test.
4		No	Go to next step.
5	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	REPAIR circuit (G/R) at the SJB. REPEAT the self-test.
5		No	CHECK the charging system. See CHARGING SYSTEM INSPECTION AND VERIFICATION .
6	CHECK THE GROUND CIRCUIT FOR AN OPEN Measure the resistance between 4WD control module 0318-03 pin 3 circuit (B/W), harness side and ground. Is the resistance less than 5 ohms?	Yes	Disconnect all 4WD control module connectors. CHECK for corrosion and/or pushed-out pins. The condition may have been caused by a loose or corroded connector. REPAIR or CLEAN as necessary. If not INSTALL a new 4WD control module. see 4WD CONTROL MODULE REMOVAL / INSTALLATION . REPEAT the self-test.
6		No	REPAIR the affected circuit(s). REPEAT the self-test.