* * CONFIDENTIAL * *
Technical Service Bulletin 2017-0938

DATE:

March 1, 2017

TO:

E-ONE Dealers and Customers

FROM:

Kevin Kearns, Customer Support Manager

SUBJECT: 300 amp Pump Primer Motor Fuse
E-ONE vehicles are designed with electrical circuit protection (e.g. fuses), to provide overcurrent
protection during short-circuit conditions or malfunction of components. Fuses are sometimes
shared amongst different circuits. For example, the circuits for the pump primer motor and chassis
power share a common 300Amp fuse. If either of these circuits experiences an electrical
overload, the fuse will act as designed to protect the users and the vehicle from further damage.
As such, an overcurrent condition in the pump primer circuit will also disconnect main power from
the cab and chassis and cause the engine to shut down. Take note that the pump primer is
interlocked with the parking brake, so this condition can only exist while the vehicle is stationary
and the pump primer motor switch is being activated.
E-ONE recommends that personnel be made aware of this condition, and trained to replace the
300Amp fuse to restore chassis power, in the unlikely event that an overcurrent condition in the
pump primer circuit results in a blown 300Amp fuse. Please find attached work instruction: “Main
Fuse Replacement Instructions”, which details the procedure to replace the 300Amp Main fuse.
Alternatively or in addition to the above training, the pump primer motor circuit can be isolated
from the main chassis circuit, to prevent loss of chassis power if the 300Amp fuse blows during a
pump primer motor circuit overcurrent condition. Attached is a work instruction: “Pump Primer
Motor Dedicated Fuse Installation”, which details how to effectively separate the two circuits
and add a dedicated and protected circuit for the pump primer motor. It also includes a list of
recommended parts.
This is considered a product improvement, and will be a running change on newly built E-ONE
apparatus. This is not considered a warrantable issue.
If you have questions concerning this bulletin, please contact the E-ONE Customer Support
Department at (352) 861-3612.

Kevin Kearns
Customer Support Manager

Main Fuse Replacement Instructions
Summary:
This document will serve as instructions on replacing a main 300 amp fuse. This instruction can
be used on both custom and commercial trucks.
Parts Required:
Bussman ANN-300 amp Fuse-672721
IMPORTANT: Before starting any of the instructions below. Turn off main power to the
truck. 12vdc will be present on the battery side stud, so use care when loosening the nuts.
Instructions:
1. Locate the main 300 amp fuse for the truck.

Example of 300 Amp Fuse

a. Commercial chassis will be in the located close to the master battery switch
beneath the cab.

2. Loosen both brass nuts on the two j-blocks. It should not be necessary to remove them
completely as the fuse is slotted.

3. Remove old fuse and reinstall new fuse.

4. Retighten the two nuts.

Pump Primer Motor Dedicated Fuse
Installation Instructions
Summary:
This document will serve as instructions on installing a dedicated fuse for the pump primer
motor. This installation instruction can be used on both custom and commercial trucks.
Parts Required:

KIT 300A PUMP PRIMER MOTOR FUSE – 1061857
Note: The kit above contains all of the parts below.
Bussman Single Stud Buss Bar-692050
Bussman Insulated Nut-692049
Bussman MRBF 300 amp fuse-692067
IMPORTANT: Before starting any of the instructions below. Disconnect all batteries both
positive and negative terminals.
Instructions:
1. Locate the main 300 amp fuse for the truck.

Example of 300 Amp Fuse

a. Commercial chassis will be in the located close to the master battery switch beneath
the cab.

2. Locate the pump primer motor power cable at the fuse.
a. The cable will be a 2ga cable located on the load side of the fuse.
b. Cable will be marked “Primer”. If marking is not visible, then a continuity
check or tracing the cable can be done to verify the right one.
3. Remove cable from the load side of the fuse.
4. Install the buss bar (692050) onto the battery side of the 300 amp fuse (See example
below).
5. Install the MRBF fuse (692067) onto the buss bar (See Example Below).
6. Install the primer motor cable onto the fuse and secure with the insulated nut (692049)
(See example below).
a. Installing the cable may require the removal of tie wraps to pull extra length to
install on the new fuse.

Example of Typical Fuse Installation

7. Reinstall battery cables.
8. Test functionality of pump primer motor.