Operation - Section 3 10/00 OM3023 Page 3-6 Operating Instructions STARTING THE ENGINE Rotate key switch fully clockwise to "start" position (with Transmission Range Selector in "Neutral") and HOLD this position until engine starts (see NOTE below). "Start" position is spring loaded to return to "On" when key is released. Electric starters and engine grid heaters can be a significant electrical drain on vehicle batteries. The vehicle battery charging system should be monitored and maintained at all times, especially during cold weather operation. When temperature is below 3°C (38°F), do not leave key switch "ON" (engine not operating) for extended periods of time (i.e. troubleshooting).
NOTE: This truck is equipped with an engine prelube system. With this feature, a noticeable time delay may occur (while engine lube oil passages are being filled and pressurized) before engine cranking will begin. The truck cannot be push started. Transmission lube and control systems are not operational when engine is not running. STARTING THE ENGINE IN COLD WEATHER The truck is equipped with an Automatic Cold Start Aid which senses intake manifold temperature and automatically turns electric grid heaters in the engine intake manifold "On/OFF".
When getting a battery assist from one truck to another, use the following procedure to avoid the possibility of causing sparks near the battery where explosive gases may be present. a. All switches must be "Off" prior to making any connections. When the key switch is turned "ON" and the manifold temperature is below 3°C (38°F), the Automatic Cold Start system will energize the engine intake manifold grid heaters. Auto grid heater activation time (t) is: b. Be certain to maintain correct polarity. NOTE: HD785 trucks are equipped with four 12 volt batteries connected in series and parallel to provide 24 volt output.
Be certain to maintain correct voltage and polarity when connecting booster cables. Damage to electrical components may result if voltage and polarity are not correct. t1 = 15 sec @ 3°C (38°F) t2 = 30 sec @ -12°C (10°F) The heater pilot lamp (instrument panel, to right of steering column) will illuminate during heating cycle. c. Connect one lead of booster cable to 24V positive (+) post of battery needing assist, and other lead of the booster cable to the 24V positive (+) post of auxiliary battery (power source). When the light goes "out", turn the key switch to the "Start" position and hold this position until engine starts. (See prelube NOTE above.) d.
Connect one lead of second booster cable to 24V negative (-) post of auxiliary battery (power source) and then connect other lead of the booster cable to a good frame ground on the disabled truck away from the battery needing assist. CAUTION: Do not crank engine with an electric starter for more than 30 seconds. Severe damage to starter motor can result from overheating. Allow two minutes for starter motor cooling before attempting to start engine again. If engine does not start, turn key switch "Off", wait for at least two minutes, and repeat the above procedure. Under normal conditions, there is no need to use the Manual Cold Start Switch.
(Refer to "Instrument Panel and Indicators", this Section.) If it is very cold, and the prelube runs a long time, the manual switch can be used to maintain pre- heating.