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Automatic Disconnecting Differential: Other Toyota 4Runner III

Differentials & Drive Axles 4 illustrations ~1023 words

COMPONENT TESTS

Note. If ADD fails to shift correctly, test ADD components for proper operation. If components are okay, check wiring circuit. See WIRING DIAGRAMS .

Tacoma & 4Runner

Using a hand-held vacuum pump, apply 20 in. Hg to 90-degree port at end of ADD actuator. Sleeve fork should move toward actuator. Apply 20 in. Hg to other ADD actuator port. Sleeve fork should move away from actuator. Ensure actuator holds vacuum at both ports. If sleeve fork does not move as specified or actuator does not hold vacuum, replace ADD actuator.

Tundra

Disconnect actuator connector. Measure resistance between terminals No. 2 and 6. (Scheme 17) Resistance should be 0.3-100 ohms. Measure resistance between terminals No. 2 and 6 and body ground. Resistance should be more than 0.5 ohms. If resistance value is not as specified, replace actuator assembly.

Scheme 17

Scheme 17: Tundra
Scheme 17: Tundra

Scheme 18

Scheme 18: Tacoma & 4Runner
Scheme 18: Tacoma & 4Runner
  1. Disconnect electrical connector from ADD relay. ADD relay is located left of glove box, behind instrument panel. see scheme 1 Using ohmmeter, ensure continuity exists between relay terminals No. 2 and 4, and No. 1 and 3. (Scheme 18)
  2. Apply battery voltage and ground to terminals No. 2 and 4. Ensure continuity exists between terminals No. 3 and 5. Replace ADD relay if defective. Reinstall electrical connector.
  1. Disconnect electrical connector from ADD relay. ADD relay is located behind instrument panel. see scheme 2 Ensure continuity exists between relay terminals No. 1 and 2, No. 2 and 4, and No. 6 and 7. (Scheme 19)
  2. There is a diode between terminals No. 6 and 7. If no continuity exists, ensure that continuity exists when reversing test leads.
  3. Apply battery voltage to terminals No. 5 and 6. Ensure continuity exists between terminals No. 1 and 3.
  4. Apply battery voltage and ground to terminals No. 2 and 7. Ensure continuity exists between terminals No. 9 and 10. Replace ADD relay if defective. Reinstall electrical connector.

Scheme 19

Scheme 19
Scheme 19

Note. ADD solenoids may also be referred to as ADD Vacuum Switching Valve (VSV).

  1. Disconnect electrical connectors from ADD solenoids, located near driver's side of engine compartment. see scheme 1
  2. To check ADD solenoid resistance, using ohmmeter, measure resistance between electrical terminals on each ADD solenoid. Resistance should be 37-47 ohms. If resistance is not as specified, replace ADD solenoid.
  3. To check each ADD solenoid operation, connect battery voltage to electrical terminals on ADD solenoid. Apply air pressure to port "E". Ensure air passes from port "F" and not out air filter. Perform STEP 1 in illustration. (Scheme 20)
  4. Disconnect battery voltage from electrical terminals on ADD solenoid. Apply air pressure to port "E". Ensure air passes from air filter and not port "F". Perform STEP 2 in illustration. (Scheme 20) Replace ADD solenoid if defective.

Scheme 20

Scheme 20
Scheme 20

ADD INDICATOR SWITCH

  1. Remove ADD indicator switch. See «ADD INDICATOR SWITCH»(ref-8759-S36016808782000092100000) under REMOVAL & INSTALLATION. Fully depress pin on end of ADD indicator switch. Using ohmmeter, ensure continuity is present between electrical terminals on ADD indicator switch with pin depressed.
  2. Release pin on end of ADD indicator switch. Continuity should not be present between switch terminals. Replace ADD indicator switch if defective.
  1. Remove transfer indicator switch. See «TRANSFER INDICATOR SWITCH (TUNDRA)»(ref-8759-S23698470582000092100000) under REMOVAL & INSTALLATION. Fully depress pin on end of transfer indicator switch. Using ohmmeter, ensure continuity is present between electrical terminals on transfer indicator switch with pin depressed.
  2. Release pin on end of transfer indicator switch. Continuity should not be present between switch terminals. Replace transfer indicator switch if defective.

Tacoma

  1. On 2WD models, connect battery voltage to terminal No. 2 of limit switch. Connect ground to terminal No. 3. Connect positive ohmmeter lead to terminal No. 5 and negative lead to terminal No. 4. See «WIRING DIAGRAMS»(ref-8759-S06415358512000092100000) . Ensure that there is continuity between terminals No. 4 and 5.
  2. On 4WD models, connect battery voltage to terminal No. 3 of switch. Connect ground to terminal No. 2. Connect positive ohmmeter lead to terminal No. 6 and negative lead to terminal No. 4. See «WIRING DIAGRAMS»(ref-8759-S06415358512000092100000) . Ensure that there is continuity between terminals No. 4 and 6.
  3. If continuity is not as specified, replace actuator assembly.
  1. Connect actuator connector. Shift transfer shift lever/transfer operation switch to H2 position. Check ADD actuator operation by sound. Disconnect actuator connector.
  2. Ensure there is no continuity between terminals No. 1 and 3, No. 1 and 4, and No. 4 and 5. See «WIRING DIAGRAMS»(ref-8759-S06415358512000092100000) . Ensure there is continuity between terminals No. 3 and 5. Connect actuator connector.
  3. Shift transfer shift lever/transfer operation switch to H4 position. Check ADD actuator operation by sound. Disconnect actuator connector.
  4. Ensure there is no continuity between terminals No. 1 and 4, No. 3 and 5, and No. 4 and 5. Ensure there is continuity between terminals No. 1 and 3. See «WIRING DIAGRAMS»(ref-8759-S06415358512000092100000) . Connect actuator connector.
  5. If continuity is not as specified, replace actuator assembly.

4Runner

  1. Connect actuator connector. Shift transfer shift lever/transfer operation switch to H2 position (2WD). Check ADD actuator operation by sound. Disconnect actuator connector.
  2. Ensure there is no continuity between terminals No. 1 and 4, No. 1 and 5, No. 4 and 5, No. 4 and 6, and No. 5 and 6. See «WIRING DIAGRAMS»(ref-8759-S06415358512000092100000) . Ensure there is continuity between terminals No. 1 and 6. Connect actuator connector.
  3. Shift transfer shift lever/transfer operation switch to H4 position. Check ADD actuator operation by sound. Disconnect actuator connector.
  4. Ensure there is no continuity between terminals No. 1 and 5, No. 1 and 6, No. 4 and 5, No. 4 and 6, and No. 5 and 6. Ensure there is continuity between terminals No. 1 and 4. Connect actuator connector.
  5. Shift transfer shift lever/transfer operation switch to H4L or L4L position. Check ADD actuator operation by sound. Disconnect actuator connector.
  6. Ensure there is no continuity between terminals No. 1 and 4, No. 1 and 6, No. 4 and 5, No. 4 and 6, and No. 5 and 6. Ensure there is continuity between terminals No. 1 and 5. Connect actuator connector.
  7. If continuity is not as specified, replace actuator assembly.

ADD SOLENOIDS

Note. ADD solenoids may also be referred to as ADD Vacuum Switching Valve (VSV).

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