GxT Ferret 74 02 Sensor Probe - Manual (Page 2)

Introduction
The Ferret 74 can be used to quickly and accurately diagnose the operation of
Titania and Zirconia Oxygen Sensors. At any time a rich or lean signal can be
sent to the ECM to monitor the response of the O2 Sensor.
Testing Procedures
1. Turn the unit on by pressing the SELECT Button. Use the SELECT Button
to choose between Zirconia, Titania, or Crossings tests.
2. Connect the ground lead to a good engine ground.
3. Connect the test lead to the signal wire that runs from the O2 sensor to
the ECM. The indicators on the 74 will help you connect to the proper
wire. All indicators should be off. Make sure the key is on, or the engine is
running.
5. Read the Rich/Lean status or Crossings per Second on the bargrarph.
In the event that the oxygen sensor probe is exposed to static discharge or
extreme electromagnetic fi elds it may step to the next operating mode. Simply
press SELECT to return to the test you wish to perform. The readings are not
affected.
Measurements and Indicators
Rich Lean Status
A single element of the bargraph will illuminate to indicate the voltage of the O2
sensor. An active sensor will display a rapidly moving segment.
Crossings per Second
Crossings per Second is a direct measurement of the activity level of the O2
Sensor. Crossings are calculated by the number of times per second that the
O2 voltage level crosses .45 volts.
Connection Indicators
There are four indicators to help you connect to the proper wire. The indicators
are: GND, ECM, HTR, and OPEN.
GND The test lead is connected to ground.
ECM The test lead is connected to the power wire running from the ECM.
Heater The test lead is connected to an oxygen sensor heater.
Open The test lead is not connected.
Zirconia The Zirconia test method has been selected
Rich Lean Signal
When the Rich Button is pressed, all of the bargraph segments under the Rich
portion of the graph will illuminate while a rich signal is sent to the ECM. When
the Lean Button is pressed, all of the bargraph segments under the Lean portion
of the graph will illuminate while a lean signal is sent to the ECM.
Sending a Rich or Lean Signal to the ECM
When you press the Rich button a Rich signal will be sent to the ECM for 5
seconds. When you press the Lean button a Lean signal will be sent to the
ECM for 5 seconds. During the time a rich or lean signal is being sent to the
ECM, all control buttons are disabled.
CAUTION: Do not continuously send a Rich or Lean signal to the ECM without
allowing time for the engine to stabilize between signals.
Analysis of Test Results
One of the most important indicators of engine performance is a properly
functioning Oxygen Sensor. A properly functioning fuel control system will have
an oxygen sensor that is rapidly oscillating between a Rich and Lean state.
We measure this as Crossings per Second. Typical crossings per second for
warm engines running at a steady fast idle are in the 1 to 3 range. Low rates
may indicate a damaged O2 sensor. Multiports usually cross count fastest, and
carbureted engines the slowest.
Using the 74 with other Equipment
When used with a variety of additional test equipment, the 74 will greatly speed
the diagnosis of drivability problems. Here are some examples.
Scan Tool
The Rich or Lean state measured by the 74 should agree with what is displayed
by the Scan Tool. Conditions that do not match will lead you to wiring or ECM
problems. Use the RICH and LEAN buttons on the 74 to force a response
from the Scan Tool.
Fuel Injector Test
Use the RICH or LEAN button on the 74 to cause a change in the pulse width
of the injector. This confi rms the ECMʼs control of fuel delivery.
Gas Analyzer
Confi rm the Oxygen Sensor is properly measuring the exhaust by comparing
the Rich Lean status with the Gas Analyzer Readings.
Technical Support
Questions or inquiries about service can be answered by contacting GxT, Inc.,
at: Toll Free (800) 627-5655. Fax: (231) 627-2727, Toll Free (231) 782-0616, or
[email protected]. When sending an item to the factory address it to:
GxT, Inc., 520 MM Riggs Drive., Cheboygan, MI 49721-1061
Include a note describing the problem.