OM3005.3 7/96 Operation - Section 3 Instrument Panel and Controls Page 3-19 (30) Left Turn Indicator (Red Light) Retarder Operation This light flashes to indicate that the left turn signal lights on the truck have been activated. It will also flash simultaneously with right turn signal indicator (32) when "Hazard" switch (on steering column) is On. When approaching a descending grade, the operator should slow the truck and select the proper transmis- sion gear range to maintain an engine speed of 1650 -- 2350 RPM (green area on tachometer) and the brake oil temperature below 250 o F (121 o C) during retarder operation. Refer to the Grade/Speed decal in the cab above the windshield.
When descending a grade, the operator should apply the retarder pedal and observe both the Tachometer and the Brake Oil Temperature Gauge (27). The en- gine RPM must be maintained at 1650 -- 2350 RPM (green area on tachometer) and the Brake Oil Tem- perature must be maintained below 250 o F (121 o C). (31) High Beam Indicator (Blue Light) The high beam indicator light, when lit, indicates that the truck head- lights are on "High" beam. To switch headlights to "High" or "Low" beam, pull lever-operated dimmer switch (turn signal lever) and release.
If the operator observes that either the maximum en- gine speed of 2350 RPM or the Brake Oil Temperature of 250 o F (121 o C) are about to be exceeded, the opera- tor should immediately move the transmission range selector to the next lower range and apply the service brakes until the truck is slowed to a speed which will permit the transmission to downshift to the gear range selected. Continue this procedure to downshift to the required gear range to maintain engine speed at 1650 -- 2350 RPM and brake oil temperature below 250 o F (121 o C). The service brakes should be used only long enough to slow the truck to allow the transmission to downshift.
When the proper gear range is attained, continue using the retarder to maintain a safe, produc- tive speed. (32) Right Turn Indicator (Red Light) This light flashes to indicate that the right turn signal lights on the truck have been activated. It will also flash simultaneously with left turn signal indicator (30) when "Hazard" switch is On. (33) Tachometer and Hourmeter If brake oil temperature exceeds 250 o F (121 o C), the Brake Oil Temperature Warning light (48) will turn on. As quickly as safety will permit, bring the truck to a complete stop away from traffic, move transmission range selector to "Neutral", apply the parking brake, and run engine at high idle.
Continue to run engine at high idle until Brake Oil Temperature Warning light turns off and brake oil temperature cools to below 250 o F (121 o C). If temperature does not return to this range within a few minutes, report the condition imme- diately to maintenance personnel and wait for further instructions before moving truck. This gauge includes an Hourmeter to register engine hours of operation and a Tachometer which registers engine speed in hundreds of Revolutions Per Minute (RPM). Adjusted Engine Speeds are: Low Idle -- 700 ± 25 RPM. High Idle, No load -- 2350 RPM Governed Speed -- 2100 RPM