Toyota Tundra Service Manual: Charging System

On-vehicle Inspection

ON-VEHICLE INSPECTION

PROCEDURE

1. CHECK BATTERY CONDITION

NOTICE:

If the battery is weak or if the engine is difficult to start, perform the following procedures.

(a) Check the battery for damage and deformation. If severe damage, deformation or leakage is found, replace the battery.

(b) Check the electrolyte quantity of each cell.

(1) For maintenance-free batteries:

  • If the electrolyte quantity is below the lower line, replace the battery.
  • If the electrolyte quantity is above the lower line, check the battery voltage when cranking the engine. If the voltage is below 9.6 V, recharge or replace the battery.

    HINT:

    Before checking the battery voltage, turn off all the electrical systems (headlights, blower motor, rear defogger, etc.).

(2) For non-maintenance-free batteries:

  • If the electrolyte quantity is below the lower line, add distilled water to each cell. Then, recharge the battery and check the electrolyte's specific gravity.

    Standard specific gravity:

    1.25 to 1.29 at 20°C (68°F)

  • If the electrolyte quantity is above the lower line, check the battery voltage when cranking the engine. If the voltage is below 9.6 V, recharge or replace the battery.

    HINT:

    Before checking the battery voltage, turn off all the electrical systems (headlights, blower motor, rear defogger, etc.).

(c) Turn the ignition switch off and turn on the headlight for 20 to 30 seconds. This will remove the surface charge from the battery.

(d) Measure the battery voltage between the negative (-) and positive (+) terminals of the battery.

Standard voltage:

12.5 to 12.9 V at 20°C (68°F)

If the voltage is below the specification, recharge the battery.

2. INSPECT BATTERY TERMINAL AND FUSE

(a) Visually check the battery terminals.

(1) Check that the battery terminals are not loose or corroded.

Torque:

Positive (+) battery terminal :

5.9 N·m {60 kgf·cm, 52 in·lbf}

Negative (-) battery terminal :

5.9 N·m {60 kgf·cm, 52 in·lbf}

(b) Check the H-fuse and fuses.

(1) Measure the resistance according to the value(s) in the table below.

Standard resistance:

Tester Connection

Condition

Specified Condition

ALT H-fuse

Always

Below 1 Ω

ALT-S fuse

MET fuse

LH-IG fuse

If the result is not as specified, replace the fuse as necessary.

3. INSPECT FAN AND GENERATOR V BELT

4. INSPECT GENERATOR WIRING

(a) Visually check the generator wiring.

(1) Check that the wiring is in good condition.

5. CHECK FOR ABNORMAL NOISES

(a) Listen for abnormal noises from the generator.

(1) Check that no abnormal noises are heard from the generator while the engine is running.

6. INSPECT CHARGE WARNING LIGHT CIRCUIT

(a) Turn the ignition switch to ON. Check that the charge warning light comes on.

(b) Start the engine and check that the light goes off.

If the light does not operate as specified, troubleshoot the charge warning light circuit.

7. INSPECT CHARGING CIRCUIT WITHOUT LOAD

(a) Connect a voltmeter and ammeter to the charging circuit as follows.

(1) Disconnect the wire from terminal B of the generator, then connect it to the negative (-) lead of an ammeter.

(2) Connect the positive (+) lead of the ammeter to terminal B of the generator.

(3) Connect the positive (+) lead of a voltmeter to the positive (+) terminal of the battery.

(4) Ground the negative (-) lead of the voltmeter.

(b) Check the charging circuit.

(1) Keep the engine speed at 2000 rpm and check the reading on the ammeter and voltmeter.

Standard current:

10 A or less

Standard voltage:

13.2 to 14.8 V

If the voltmeter reading is higher than the standard voltage, replace the voltage regulator.

HINT:

If the battery is not fully charged, the ammeter reading will sometimes be higher than the standard current.

8. INSPECT CHARGING CIRCUIT WITH LOAD

(a) With the engine running at 2000 rpm, turn the high beam headlights ON and turn the heater blower switch to the "HI" position.

(b) Check the reading on the ammeter.

Standard current:

30 A or higher

If the ammeter reading is below the standard current, repair the generator.

HINT:

If the battery is fully charged, the indication will sometimes be below the standard current. If this is the case, add more electrical load (operate the wipers, rear window defogger, etc.) and check the reading on the ammeter again.

Parts Location

PARTS LOCATION

ILLUSTRATION

Precaution

PRECAUTION

1. PRECAUTION

(a) Check that the battery cables are connected to the correct terminals.

(b) Disconnect the battery cables when the battery is given a quick charge.

(c) Do not perform tests with a high voltage insulation resistance tester.

(d) Never disconnect the battery while the engine is running.

(e) Check that the charging cable nut is securely installed to terminal B of the generator and the fuse box.

System Diagram

SYSTEM DIAGRAM

    1ur-fe Charging

    Generator

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