Electronic Locking Differentials: Other Lexus LX J100

Differential Lock Control System Off

Check for blown fusible link or blown DIFF fuse. Ensure bulb, wiring harness, and ground circuit are okay. See WIRING DIAGRAMS . Repair circuit(s) or replace components as necessary.

Differential Lock Control System On

Check for blown DIFF or 4WD fuse. Ensure differential lock control switch is okay. Ensure 4WD control unit, wiring harness, and ground circuit are okay. See WIRING DIAGRAMS . Repair circuit(s) or replace components as necessary.

DIFFERENTIAL LOCK DOES NOT OPERATE

Ensure differential lock control switch, actuator(s), and differential carrier are okay. Ensure 4WD control unit, wiring harness, and ground circuit are okay. See WIRING DIAGRAMS . Repair circuit(s) or replace components as necessary.

DIFFERENTIAL LOCK DOES NOT RELEASE

Ensure vehicle speed sensor is okay. Ensure 4WD control unit, wiring harness, and ground circuit are okay. See WIRING DIAGRAMS . Repair circuit(s) or replace components as necessary.

Scheme 28

1. Raise vehicle off ground and support with jackstands, so all 4 wheels can rotate. Start engine and place transfer case shift lever in "L" position on Land Cruiser, "L4" position on Tacoma, and 4WD position on 4Runner. On Land Cruiser, turn differential lock control switch to "RR", on all other models turn differential lock control switch on. Ensure indicator light turns on. Go to next step.
2. If light indicator light is blinking, rotate tires to engage differential gears. Turn differential lock control switch off, and ensure indicator light turns off. Go to next step.
3. Turn differential lock control switch on. Locate 4WD control unit. see scheme 1, see scheme 2 or see scheme 3. With wheels turning at 5 MPH, measure voltage between 4WD control unit terminals No. 2 and 3 by backprobing connector. (Scheme 28) Voltage should be 0.5 volt or less. If voltage is not as specified, check wiring harness for short to voltage. See «WIRING DIAGRAMS»(ref-8780-S26603566332000092200000). Repair as necessary. Turn differential lock control switch off. Stop engine and lower vehicle.

Scheme 29

1. Ensure battery voltage is 10-14 volts. Disconnect 4WD control unit connector. Turn ignition on and go to next step.
2. Check differential lock actuator circuit. Using ohmmeter, measure resistance between 4WD control unit wiring harness connector terminals No. 2 and 3. (Scheme 29) Resistance should be less than 100 ohms. If resistance is as specified, go to next step. If resistance is not as specified, go to step 9.
3. Check ground circuit. Check continuity between 4WD control unit wiring harness connector terminal No. 7 and ground. Continuity should exist. If continuity is as specified, go to next step. If continuity is not as specified, go to step 9.
4. Check vehicle speed sensor circuit. Check continuity between 4WD control unit wiring harness connector terminal No. 10 and ground. Move vehicle slowly (at least 5 MPH). A pulse of continuity should exist for each 15.8" (401 mm) of movement. If continuity is as specified, go to next step. If continuity is not as specified, go to step 9.
5. Check DIFF fuse circuit. Measure voltage between 4WD control unit wiring harness connector terminal No. 5 and ground. If battery voltage is not present, check and replace fuse as necessary. If fuse is okay, go to step 9. If battery voltage is present, go to next step.
6. Check differential lock position switch circuit. Measure voltage between 4WD control unit wiring harness connector terminal No. 1 and ground. When differential lock indicator light is on, no voltage should be present. When differential lock indicator light is off, 10-14 volts should be present. If voltage is as specified, go to next step. If voltage is not as specified, go to step 9.
7. Check 4WD position switch circuit. Measure voltage between 4WD control unit wiring harness connector terminal No. 8 and ground. With 4WD shift lever in "N" or "H" position, no voltage should be present. With shift lever in "L" position on Land Cruiser, "L4" on Tacoma, and 4WD on 4Runner, voltage should be 10-14 volts. If voltage is as specified, go to next step. If voltage is not as specified, go to step 9.
8. Check differential lock control switch circuit. Measure voltage between 4WD control unit wiring harness connector terminal No. 4 and ground. With control switch off, no voltage should be present. With control switch on, 10-14 volts should be present. If voltage is as specified, go to step 10. If voltage is not as specified, go to next step.
9. Check components and wiring harness. Check appropriate component (if necessary). See «COMPONENT TESTS»(ref-8780-S39541636452000092200000). Replace as necessary. If appropriate component is okay, check harness and connectors for terminal damage, corrosion or pins pushed out. Repair or replace as necessary and retest system.
10. Check circuit with control unit connected. Turn ignition off. Connect 4WD control unit connector. Turn ignition on. With differential control switch in specified positions, check voltage at 4WD control unit by backprobing connector. (Scheme 28) See «TESTING DIFFERENTIAL LOCK CONTROL OPERATION»(ref-8780-S10116955892000092200000) table. If voltage is not as specified, replace 4WD control unit. TESTING DIFFERENTIAL LOCK CONTROL OPERATION Measure Between Terminal No.'s (1) Control Switch Position Specified Voltage 8 & 7 Land Cruiser (2) 10-14 Tacoma & 4Runner (2) 0.5 Or Less 1 & 7 On 0.5 Or Less 3 & 2 Off-On (3) 10-14 2 & 3 On-Off (3) 10-14 (1) Connect voltmeter positive lead to first terminal listed, and negative lead to second terminal. (2) With 4WD shift lever in "L"position on Land Cruiser, "L4" on Tacoma and 4WD on 4Runner. (3) Voltage is present for about one second then drops down to 0.5 volt or less.

DIFFERENTIAL LOCK ACTUATOR

Raise and support vehicle. Using a spare heater main relay, connect battery voltage as shown. (Scheme 30) Rotate rear tire and ensure differential locks or is free. If differential does not operate as specified, replace actuator.

Scheme 30

DIFFERENTIAL LOCK CONTROL SWITCH

Check differential lock control switch continuity between switch terminals No. 1 and 4. (Scheme 31)or (Scheme 32). If continuity does not exist, replace differential control switch.

Scheme 31

Scheme 32

Front Or Rear

Disconnect indicator light switch connector. Remove switch by unscrewing from differential. Using a DVOM, ensure continuity exists between terminals of switch when switch is depressed. Ensure continuity does not exist when switch is released. If continuity is not as specified, replace switch.

Land Cruiser

1. Lock rear differential. Disconnect negative battery cable. Remove actuator protector(s). Disconnect electrical connectors and bleeder tube. Remove rear differential lock position switch. Remove 3 bolts and differential cover. (Scheme 33)
2. Remove shift fork set bolt. (Scheme 34) Remove differential lock actuator mounting bolts, and remove actuator.
3. Clean all mating surfaces, set bolt threads and shaft fork. Apply form-in-place type gasket sealant to actuator. Install actuator to differential, matching shaft with shaft fork hole. Apply Loctite to threads of fork set bolt. Install and tighten set bolt to 14 ft. lbs. (20 N.m).
4. Install differential lock actuator mounting bolts and tighten evenly to 17 ft. lbs. (24 N.m). Apply form-in-place type sealant to differential cover mating area, and install cover. To complete installation, reverse removal procedures. With ignition on, turn differential lock control switch off. Ensure differential lock is released.

Scheme 33

Scheme 34

Scheme 35

Scheme 36

Scheme 37

1. Disconnect negative battery cable. Remove actuator plastic cover, if equipped. Disconnect electrical connector. Remove bolts and actuator.
2. To install actuator, ensure that outermost rack tooth of shift fork is above center line of actuator installation hole. (Scheme 35)
3. Ensure matchmarks of actuator pinion are between 0 and 5 degrees clockwise above center line of actuator. (Scheme 36) If needed, use 1.5 volt dry cell battery to rotate pinion to correct position.
4. Coat new "O" ring with gear oil. Install "O" ring to actuator. Apply grease to pinion. Install actuator with elongated slot on actuator aligned with knock pin on side of carrier. Ensure pinion meshes with rack tooth of shift fork. With actuator installed, rotate actuator counterclockwise until knock pin contacts right hand side. (Scheme 37) Install bolts and tighten to 20 ft. lbs. (26 N.m).

Center & Rear Differential Lock System Wiring Diagram (1999 Land Cruiser & Lexus LX470). Scheme 38

Center & Rear Differential Lock System Wiring Diagram (2000 Land Cruiser). Scheme 39

Rear Differential Lock System Wiring Diagram (1999 Tacoma). Scheme 41

Rear Differential Lock System Wiring Diagram (2000 Tacoma - Except California). Scheme 42

Rear Differential Lock System Wiring Diagram (2000 Tacoma - California). Scheme 43

Rear Differential Lock System Wiring Diagram (1999-2000 4Runner). Scheme 44