Star Headlight & Lantern Optimax-DH RP242 - Manual (Page 11)

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5. Check each head. If the leads in one of the heads have shorted out, the
output voltage of the other heads may be held down as well. To test for this,
unplug all of the heads and plug them in individually (one at a time). If your
problem is a result of a shorted head, then each good head should function
properly when connected by itself. Note: A burned out strobe tube does not
cause a short and will not affect the operation of the remaining heads. If the
problem is not with a shorted head and if proper voltage is reaching the
pack, the problem is most likely internal to the pack. Call Star to obtain an
R.G.A. number to return the pack for service.
Checking a Bad Power or Ground Connection
If sufficient voltage is not reaching the pack perform the following tests:
1. Test the Power at the Battery: With the vehicle turned off and while the
pack is running, measure the battery voltage at the battery. A nominal 12.5
volts should exist. If this voltage is below 9.5 volts the pack will not function
properly and the problem is with the battery. This reading should not be
more than 1-1.25 volts higher than the reading at the strobe pack itself.
2. Test the Power Wire Between the Battery and the Switch: Move to the
ON/OFF switch in the cab and gain access to the rear of the switch panel.
With the vehicle not running and the pack on at the high power setting,
measure the voltage drop in the red wire by taking a reading with one probe
on the positive side of the battery and the other probe in pin 1 of your switch.
If this reading exceeds 0.25 volts then there is a poor connection between
the switch and the battery in the red wire and it should be checked. NOTE:
Excessive voltage drop may be occurring in the connections on the switch
panel. If you have one of our switches you can increase the contact
pressure by removing the FASTON terminal from the tab on the switch.
Using long nose pliers, gently squeeze the FASTON terminal together in the
area that slides on to the tab of the switch. This will increase the pressure
applied between the tabs and the connector and reduce voltage drop.
3. Test the Power Wire Between the Strobe Pack and the Switch: This
same procedure can be used to check the wires between the switch panel
and the pack. Place one probe on the terminal at the switch and the other
probe into the terminal with the corresponding wire color in the PWR
connector on the pack. Once again if any of the readings exceed 0.25 volts
then you should check those wires and their connections.
4. Test your Ground Wire: If you still have not located the problem,
troubleshoot the connections between the good chassis ground and pin 2
(black wire) of the PWR connector on the power pack. With the vehicle not
running and the pack on at the high power setting, measure the voltage drop
in the Black (Ground) wire by taking a reading with one probe on the
negative side of the battery and the other probe in pin 2 of your PWR
connector. If this reading exceeds 0.25 volts then you have a bad ground.