Lull 944E-42 Service Manual Manuel d'utilisateur télécharger pdf (Page 531)

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101

9.21

Model 644E-42/944E-42 Rev. 6/04

Electrical System

9.7 FUSES AND RELAYS

Fuses and relays help to protect the electrical system. In

general, a blown fuse is a symptom of another electrical

problem. Address the true problem, not just the symptom.

Simply replacing the fuse often will not solve the problem.

Blown fuses are usually due to simple causes, including

loose or corroded connections, or a defective relay.

There are two main causes of blown fuses; a shorted or

grounded wire in the applicable circuit, or a defective

electrical component. Visually check the condition of the

fuse, wires, connections and components in the involved

circuit before replacing a fuse. Check the circuit for

shorts, grounding, or defective electrical components.

Keep in mind that many parts in the electrical system

work with components of the hydraulic system; a careful

inspection of the related hydraulic components may help

in solving problems.

9.7.1 Circuit Protection - Fuses

a. Auto Type Fuses

The fuse is the most common method used for protecting

wiring circuits. A good fuse (1) will have the center

element connected to both sides of the fuse. Whenever

there is an excessive amount of current flowing through a

circuit the fusible element will melt (2) and create an open

or incomplete circuit.

Fuses are a one time protection device and must be

replaced each time the circuit is overloaded. To

determine if a fuse is open (2), remove the suspected

fuse and examine the element in the fuse for an open

(break). If not broken, also check for continuity using a

DMM or a continuity tester. If the element is open or

continuity is suspect, replace the fuse with one of equal

current rating.

b. Cable Type Fusible Link

(644E-42, SN 0160003690 & After Only)

There is a cable type fusible link (3) connected to the B+

terminal on the alternator and the 12V starter buss bar.

This fusible link is used for protecting the starter to

alternator circuit. A good cable will have the center fusible

link connected to both sides of the cable. Whenever there

is an excessive amount of current flowing through the

circuit, the fusible element will melt (4) and create an

open or incomplete circuit. This will not be a visible break.

To determine the status of this cable, with the ignition in

the OFF position, check for battery voltage at the

alternator connection. If there is no battery voltage the

element is open.

MT0420

Fuse Types

Current Rating Amperes Color

Auto Fuses, Mini Fuses

1Black

2Gray

3Violet

5 Tan

7.5 Brown

10 Red

15 Blue

20 Yellow

25 White

30 Green

Maxi Fuses

20 Yellow

30 Light Green

40 Orange or Amber

50 Red

60 Blue

MU6640

1 2 ... 526 527 528 529 530 531 532 533 534 535 536 ... 845 846

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Lull 944E-42 Service Manual Manuel d'utilisateur Page 531

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