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School Bus Tech Tip of the Month:


Follow these guidelines for engines that comply with EPA10 or newer regulations, or damage may occur to the ATD and the warranty may be compromised.

  • Use ultralow-sulfur diesel with 15 ppm sulfur content or less.
  • Do not use fuel blended with used engine lube oil or kerosene.
  • Engine lube oil must have a sulfated ash level less than 1.0 wt %; currently referred to as CJ-4 oil.
  • Use only certified diesel exhaust fluid (DEF) in the DEF tank.

IMPORTANT: Using non-specification fuels or oils can lead to shortened diesel particulate filter (DPF) cleaning or replacement intervals. For example, using CJ-4+ oil with 1.3% sulfated ash (30% more ash content) may result in the need for DPF cleaning or replacement 20 to 30% sooner than would normally be required.


Fuse identification

CAV Description Fuse
F1 VCU (spare) 10A (—)
F2 Blower Motor 30A
F3 Engine ECU 20A
F5 Ignition Switch 10A
F6 Hydromax RLY (spare) 30A (—)
F7 Stepwell HTR RLY LO/HI 30A
F8 ICU3-M2 10A
F9 Transmission ECU 10A
F10 Expansion Module 1 30A
F11 Expansion Module 1 30A
F12 Radio/Diagnostic 20A
F13 Expansion Module 1 30A
F14 Expansion Module 2 30A
F15 Bulkhead Module 30A
F17 Chassis Module 30A
F18 Bulkhead Module 30A
F19 Chassis Module 30A
F20 Bulkhead Module 30A
F21 Expansion Module 2 30A
F22 Bulkhead Module 30A
F23 Expansion Module 2 30A
F24 Hydraulic Pump and RLY (spare) 25A (—)
F25 Adjustable Pedals 10A
F26 Chassis Module 30A
F27 Heater Booster Pump 20A
F28 Bulkhead Module 30A
F29 Crossing Arm RLY 10A

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