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ZEUS Training Module 12

Applies To: ZEUS®

Functional Tests: Scanner Functional Tests, Scanner Output Controls, Actuator Tests, Custom Data List



Welcome to Snap-on Training Solutions. This module is designed to help you get the most out of your ZEUS diagnostic tool, and covers the use of scanner functional tests.

Functional Tests are a great way to isolate the cause of a problem with the controller, a component, wiring or other issues.  These tests let you override the vehicle’s controller to take control of a system and determine if the vehicle responds properly or not.

Scanner Functional Tests

Let’s start in the Scanner System menu, Select Engine.

Functional Tests are a powerful diagnostic feature that can be used to verify the operation of a component. Let’s see how these tests work. To get started, select Functional Tests.

Select Injector Balance. The next screens give us step-by-step test instructions. In our example, you would connect a fuel pressure gauge or optional pressure transducer to the fuel system pressure tap. Select Continue. 

For each injector, the Scanner will automatically turn on the fuel pump to pressurize the system. Each injector is then pulsed for a fixed time allowing you to record the drop in fuel pressure with your gauge.

You can then compare pressure drop readings between cylinders. 

Scanner Output Controls
Actuator Tests

Another useful type of functional tests is an Output Control, which monitors live output data from the vehicle while you activate vehicle components. And Actuator Tests, which check operation of devices like solenoid valves, motors, and relays.

A good example of a powerful Output Control is the AC Relay Test.

Select the test. The AC Relay control shows at the top of the screen and the live data parameter view opens. 

By using the functional test and selecting ON, you are overriding the controller.

If you command the relay to turn ON and it does NOT activate, you may have a problem with the controller and or the relay or wiring. 

If you command the relay to turn ON and it DOES activate, you’ve just eliminated those components from the possible causes. 

Use the Change List button to open the Data Menu.

Select the data group Accessory/Electrical/Theft Data.

Custom Data List

Let’s view data parameters relevant to the AC Relay Test. Tap the Custom icon on the menu.

First use the Deselect All icon to deselect all parameters.

Select just the parameters you want for your diagnosis.

To perform the AC Relay test we will select AC-related data: AC Request, AC Relay Command, AC Pressure Sensor (volts), and AC Pressure Sensor (psi).

Press OK to view your selected parameters. This will speed the data refresh rate to help you catch short, intermittent glitches.

Here's your Custom Data list. Now you can observe the vehicle data response when you command the AC relay On and Off.

Snap-on is dedicated to helping you get the most out of your diagnostic tool and keep your customers happy. Be sure to watch the rest of the modules in this Training Solutions series.

Last Updated: August 5, 2020

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