26SI Series Alternator – T2 Electrical System Current – Test

T2a – Undesired Electrical System Current – Test (For Machines Equipped With a Main Disconnect Switch)

  1. Turn off all of the accessories. Turn the keyswitch to the OFF position.
  1. Clamp a 9U-5795 Current Probe or 225-8266 Ammeter Tool Gp around the main ground cable. Clamp the tool with the positive side away from the battery. Reset the probe (zero) before you clamp the probe around the wire. Read the current.

    Expected Result: The current is below 2 A.

    Results:

    • YES – The current is below 2 A. Continue to Step 3.

    • NO – The current is above 2 A. There is a current draw in the system. Go to Testing and Adjusting, “T5 Alternator Current – Test”

  1. Turn the disconnect switch to the ON position. Connect a multimeter across the disconnect switch terminals. Connect the red lead to the terminal on the frame side. Connect the black lead to the terminal on the battery side. Use the 10A connections in order to avoid damage.
  1. Turn off the disconnect switch and read the current.

    Expected Result: The current is below .050 amperes (50 mA).

    Note: The standard acceptable current draw is 50 mA. A current draw above 50 mA usually indicates a problem. However, some large machines with multiple electronic control modules have a higher acceptable limit. Contact a Caterpillar dealer for more information.

    Results:

    • YES – The current is below 0.050 A. The charging system is currently good. The fault is possibly an intermittent draw in the system. The batteries may be faulty. Check that NO accessories were ON during the test.

    • NO – The current is above 0.050 A. There is a draw in the system. Go to Testing and Adjusting, “T5 Alternator Current – Test”.

T2b – Undesired Electrical System Current – Test (For Any Machine)

  1. Turn off all accessories. Turn the keyswitch to the OFF position.
  1. Clamp a 9U-5795 Current Probe or 225-8266 Ammeter Tool Gp around the main ground cable. Clamp the tool with the positive side away from the battery. Reset the probe (zero) before the probe is clamped around the wire. Read the current.

    Expected Result: The current is below 2 A.

    Results:

    • YES – The current is below 2 A. Continue to Step 3.

    • NO – The current is above 2 A. There is a current draw in the system. Go to Testing and Adjusting, “T5 Alternator Current – Test”

  1. Remove the ground cable from the battery terminal. For systems with 4 batteries, or 12 V systems with 2 batteries, disconnect the ground cables from both negative batteries.
  1. Connect a multimeter between the disconnected battery ground cable and one of the negative battery terminals. Connect the red positive lead of the multimeter to the cable. The negative lead should be connected to the battery terminal. Use the 10 A connections in order to avoid damage.

    Expected Result: The current is below .050 amperes (50 mA).

    Note: The standard acceptable current draw is 50 mA. A current draw above 50 mA usually indicates a problem. However, some large machines with multiple electronic control modules have a higher acceptable limit. Contact a Caterpillar dealer for more information.

    Results:

    • YES – The current is below 0.050 A. The charging system is currently good. The fault is possibly an intermittent draw in the system. The batteries may be faulty. Check that NO accessories were ON during the test.

    • NO – The current is above 0.050 A. There is a draw in the system. Go to Testing and Adjusting, “T5 Alternator Current – Test”.

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