Operation - Section 3 OM3006.3 04/98 Page 3-22 Instrument Panel and Indicators Keyswitch The keyswitch (1, Figure 3-6) is a three position (Off, Run, Start) switch. Starting fluid is extremely volatile and flammable! Use with extreme care. If truck is equipped with optional Engine Starting Aid and ambient temperature is below 50 o F (10 o C), turn the keyswitch to the ‘‘Start’’ position, and while crank- ing engine, move the Engine Starting Aid switch to the ‘‘On’’ position for three (3) seconds MAXIMUM ; then release Engine Starting Aid. If engine does not start, wait at least fifteen (15) seconds before repeating the procedure. Do not crank an electric starter for more than 30 seconds .
Allow two minutes for cooling before attempting to start engine again. Severe damage to starter motor can result from over- heating . Key insertion/withdrawal position -- None of the electrical circuits are en- ergized in this position. Auxiliary Brake Switch This switch (2, Figure 3-6) applies the Auxiliary Brake. Turn the switch to ‘‘OFF’’ to stop the engine. Depress the center button to apply the auxiliary brake. When the switch is ‘‘On’’, the RED lamp will illuminate. Depress the button again to release the auxiliary brake; the light will turn ‘‘Off’’. When the switch is rotated one position clock- wise, it is in the ‘‘Run’’ position.
Lamp circuits and other electrical circuits (except ‘‘Start’’) are energized in this position. With Transmission Selector Lever in the ‘‘ N eutral’’ position, rotate keyswitch fully clockwise to the ‘‘Start’’ position and hold until en- gine starts. ‘‘Start’’ position is spring loaded to return to ‘‘Run’’ when key is released. When the auxiliary brake switch is activated, full, unmodulated hydraulic brake pressure (or what- ever pressure remains, if the system is failing) is applied to all wheels. In addition, the parking brake is also applied. NOTE: The engine start circuit is equipped with the Cummins Engine Prelube System.
A noticeable time delay will occur (while engine lube oil passages are being filled) before starter engagement and engine cranking will begin. The colder the engine oil tempera- ture, the longer the time delay will be. In addition, if truck is also equipped with Engine Starting Aid for cold weather starting, the Engine Prelube System should be engaged FIRST for 5-10 seconds, or until starter is engaged, BEFORE activating the Engine Starting Aid. The operator should not apply the auxiliary brake switch when the truck is moving, except as an emergency measure. NOTE: This switch is for the manual activation of the auxiliary brake circuit by the operator.
The auxiliary brake circiut will apply automatically, if the hydraulic brake pressure decreases below a pre- set value .