HARNESS AS 8Y7958 - Caterpillar

T2a - Test for machines equipped with a main disconnect switch
Turn off all of the accessories. Turn the key switch to the OFF position.
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 clamping 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"
Turn the disconnect switch to the ON position. Connect an ammeter 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. If a multimeter is being utilized for this test, use the 10A connections in order to avoid damage.
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