How To Test The Alternator (1994-2001 3.0L V6 Toyota Camry)

TEST 2: Checking The Continuity Of The Bat (+) Cable

The electrical power generated by the alternator has to pass thru a mega-fuse to safely reach both the battery and the vehicle's electrical systems.

• Camry: 100 Amp ALT mega-fuse.
• Avalon: 120 Amp ALT mega-fuse.
• Solara: 100 Amp ALT mega-fuse.

This mega-fuse is located in the under-hood fuse/relay box, which is mounted on the left inner fender inside the engine compartment.

If the mega-fuse is blown, the alternator might still be producing power, but none of it will make it to the battery.

To check the condition of the 100A (120A) ALT fuse, we'll use a simple multimeter continuity test on the BAT+ cable.

IMPORTANT: Leave the BAT+ cable connected to the alternator during the test.

These are the test steps:

1. 1

   Disconnect the battery negative (-) cable terminal from the battery negative post. The positive cable remains connected.
   
   IMPORTANT: Don't continue to the next step without first disconnecting the negative cable from the negative battery post.

2. 2

   Set your multimeter to Ohms mode.

3. 3

   Connect the red multimeter test lead to the stud on the rear of the alternator (see photo above).
   
   The BAT + cable, which connects to the battery positive (+) terminal, is the cable that connects here.

4. 4

   With the black multimeter test lead probe the center of the battery positive (+) post on your Toyota's battery.

5. 5

   You'll get one of two results.
   
   1.) No Continuity: The multimeter will indicate a reading of OL (which means over limit).
   
   2.) Continuity: Your multimeter will register an Ohms reading of 0.5 Ohms or less.

Let's take a look at what your results mean:

CASE 1: Continuity is present. This is the expected result and confirms that the 100 (120) Amp mega-fuse is intact and functioning properly.

With this result, you can move on to the next step: TEST 3: Checking The Alternator Fuses.

CASE 2: Continuity is not present. This usually indicates that the 100 (120) Amp mega fuse is blown, which will prevent the alternator from charging the battery.

Check the mega-fuse and if blown, replace it with a new one and retest the circuit to confirm the issue is resolved.

TEST 3: Checking The Alternator Fuses

This final test involves confirming that terminals 1 and 3 of the alternator's 3-wire connector are receiving 10 to 12 Volts.

• Terminal 1 should only have power when the key is in the ON or START position.
• Terminal 2 should only have power when the key is in the ON or START position.
• Terminal 3 must always have 10 to 12 Volts, no matter the key position.

We'll use a multimeter to measure the voltage at each terminal and confirm power is present.

Let's get started:

1. 1

   Reconnect the battery to its battery negative (-) cable, that you disconnected in the previous test.

2. 2

   Disconnect the alternator's 3-wire connector.

3. 3

   Place your multimeter in Volts DC mode.

4. 4

   Connect the black multimeter test lead to the battery negative (-) post.

5. 5

   Turn the key to the ON position but don't crank or start the engine.

6. 6

   Probe terminal 1 with the red multimeter test lead.
   
   Terminal 1 should connect to a yellow (YEL) wire.

7. 7

   The multimeter should register 10 to 12 Volts DC.
   
   Terminal 1 has power only with the key in the ON and RUN positions.

8. 8

   Probe terminal 2 with the red multimeter test lead.
   
   Terminal 2 should connect to a red/blue (RED/BLU) wire.

9. 9

   The multimeter should register 10 to 12 Volts DC.
   
   Terminal 2 has power only with the key in the ON and RUN positions.

10. 10

    Probe terminal 3 with the red multimeter test lead.
    
    Terminal 3 should connect to a white (WHT) wire.

11. 11

    The multimeter should register 10 to 12 Volts.
    
    Terminal 3 should have power present at all times (whether the key is ON or not).

Let's examine your test result:

CASE 1: Terminals 1, 2, and 3 have power. This is the expected result, indicating that power delivery to the alternator is functioning correctly.

If you've already confirmed the following:

• The battery voltage is 12.5V or less with the engine running (TEST 1).
• The 100 (or 120) Amp ALT fuse is not blown (TEST 2).
• Terminals 1, 2, and 3 are receiving 10 to 12 Volts (this test section).

Then you can conclude the alternator is faulty and needs to be replaced.

CASE 2: Terminal 1 does not have power. This usually points to a blown IGN fuse.

Camry:

• 1994–1996: the IGN fuse is a 7.5A fuse located in the under-dash fuse box.
• 1997–2001: the IGN fuse is a 5A fuse in the same location.

Avalon:

• 1995–1999: the IGN fuse is a 5A fuse located in the under-dash fuse box.

Solara:

• 2000-2003: the IGN fuse is a 5A fuse located in the under-dash fuse box.

Replace the blown fuse with one of the same amperage rating. After replacing it, start the car and repeat TEST 1 to check if the alternator is now charging the battery.

CASE 3: Terminal 2 does not have power. This usually points to a blown GAUGE fuse.

Camry:

• 1994–1996: the GAUGE fuse is a 7.5A fuse located in the under-dash fuse box.
• 1997–2001: the GAUGE fuse is a 10A fuse in the same location.

Avalon:

• 1995–1999: the GAUGE fuse is a 7.5A fuse located in the under-dash fuse box.

Solara:

• 2000-2003: the GAUGE fuse is a 10A fuse located in the under-dash fuse box.

Replace the blown fuse with one of the same amperage rating. After replacing it, start the car and repeat TEST 1 to check if the alternator is now charging the battery.

CASE 4: Terminal 3 does not have power. This usually indicates a blown ALT-S fuse.

Camry:

• 1994–1996: the ALT-S fuse is a 7.5A fuse found in the under-hood fuse box.
• 1997–2001: the ALT-S fuse is a 5A fuse in the same location.

Avalon:

• 1995–1999: the ALT-S fuse is a 5A fuse found in the under-hood fuse box.

Solara:

• 2000-2003: the ALT-S fuse is a 5A fuse found in the under-hood fuse box.

Replace the blown fuse with one of the correct amperage rating. Then, start the car and repeat TEST 1 to confirm if the alternator is now charging the battery.

More 3.0L Toyota Camry Tutorials

You can find a complete list of 3.0L Toyota Camry tutorials in this index:

• 3.0L Toyota Camry Index of Articles.

Here's a sample of the tutorials you'll find there:

• How To Test Engine Compression (1992-2006 3.0L V6 Toyota Camry).
• How To Test For A Blown Head Gasket (1992-2006 3.0L V6 Toyota Camry).
• How To Test The TPS (1997-2001 3.0L V6 Toyota Camry).
• How To Test The MAF Sensor (1997-2001 3.0L V6 Toyota Camry).