Purpose:
This test verifies that the components of the test system (air supply, hoses, fittings, glad-
hands, etc.) combined with the tester's inherent
set
and
release
times complies with the maxi-
mum permissible times specified in Figure 2 of FMVSS-121, S6.1.13 as amended (Set > 0.350 sec.
(+ .005 seconds) and Release > 0.700 sec. (+ .005 seconds)).
Do not attempt vehicle brake timing
or differential tests if either of the composite times for the test system do not pass. Otherwise
you run the risk of failing otherwise 'good' vehicles.
If you are failing vehicles for apply and release
timing, re-run this test to verify the test system's performance.
1. The hardware setup needed for the 121 Timing Self–Test is the same as was just used for the
Internal Air Leak Test, which should have just completed.
2. Verify the following LED’s status on the hub:
►
The green LED should be lit indicating a good state.
►
The red LED will be lit if the hub encountered an error condition. (Likely the sensor attached
to the hub did not self-calibrate and may be defective. Or, there may be air pressure in the line,
or, there may be a low battery condition in the hub.)
►
To adjust the brightness of the display on the hub, you can adjust the small screw near the
lower right corner of the hub display.
3. The “Setup HUB Sensors” dialog should be displayed. In this dialog, identify the appropriate hub
port which has the sensor cable (coming from the 50 CI reservoir) attached to it. On that sensor
in the GUI, change “Unused” to “Curbside” to select it for use.
4. Now select “Done” in the lower right hand corner of the “Setup HUB Sensors” dialog popup.
The 121 Timing test should immediately start as a result of this action.
5. If the test is successful, the 1200 Certifier GUI
will either:
- Advance to the start of the next test,
which is the Differential Test (if it was selected to run) and
a dialog popup should be displayed telling you to connect the Diff Kit.
- OR the GUI will indicate the test passes and if you hit ‘Continue’ a “Certifier Report” will
display.
Lite-Check CERTIFIER 1200 Operations Manual
11
121 Timing Self-Test, without a trailer or dolly:
6.
But if the 121 Timing test fails,
the error will be shown which will identify the failure. The
reason for the failure will be given, such as the speed at which portions of the test were
completed, or for not selecting a valid sensor, etc.
►
If the failure is due to a sensor issue, fix the issue and then click on “Retry”.
►
If the failure is due to timing, you may have to adjust one or both of the valves on the
Air Manifold, and then click “Retry”. See the next page for how to adjust the two valves.
Please see the picture on the next page to identify the locations of the two valves.
