JLG 15VPSP Service Manual - Manual (Page 55)

SECTION 3 - TROUBLESHOOTING
3120728 – JLG Lift – 3-1
SECTION 3. TROUBLESHOOTING
3.1 GENERAL
This section contains troubleshooting information to be used for locating and correcting most operating problems. If a prob-
lem should develop which is not presented in this section or which is not corrected by listed corrective actions, technically
qualified guidance should be obtained before proceeding with any maintenance.
3.2 TROUBLESHOOTING INFORMATION
Troubleshooting procedures applicable to this machine are listed and defined starting with Section 3.5, TROUBLESHOOT-
ING SECTION - TABLE OF CONTENTS in this section of the manual.
Each malfunction within an individual group or system is followed by a listing of probable causes which will enable determi-
nation of the applicable remedial action. The probable causes and the remedial action should, where possible, be checked
in the order listed in the tables.
It should be noted that there is no substitute for a thorough knowledge of the equipment and related systems.
It should be recognized that the majority of the problems arising in the machine will be centered in the hydraulic and electri-
cal systems. For this reason, every effort has been made to ensure that all likely problems in these areas are given the fullest
possible treatment. In the remaining machine groups, only those problems which are symptomatic of greater problems
which have more than one probable cause and remedy are included. This means that problems for which the probable
cause and remedy may be immediately obvious are not listed in this section.
The first rule for troubleshooting any circuit that is hydraulically operated and electrically controlled is to determine if the cir-
cuit is lacking hydraulic oil and electrical control power. This can be ascertained by overriding the bypass valve (mechani-
cally or electrically) so that oil is available to the function valve, then overriding the function valve mechanically. If the function
performs satisfactorily, the problem exists with the control circuit.
3.3 HYDRAULIC CIRCUIT CHECKS
(See Figure 3-4.)
The first reference for improper function of a hydraulic system, where the cause is not immediately apparent, should be the
Hydraulic Diagram Circuit. The best place to begin the problem analysis is at the power source (pump). Once it is deter-
mined that the pump is serviceable, then a systematic check of the circuit components, would follow.
NOTE: For aid in troubleshooting, refer to Figure 3-4. for HYDRAULIC DIAGRAM circuit.
3.4 ELECTRICAL CIRCUIT CHECKS
General
The drive system on the VP series machine requires a microprocessor controlled electrical circuit to operate smoothly and
accurately. All platform control functions are relayed to various machine components (i.e. platform up/down, drive functions,
etc.) through the (MC-1) microprocessor box (mounted under the battery charger support bracket).
To help diagnose any problems with the components associated with the microprocessor, the MC-1 is designed with an
internal fault messaging system which is displayed by LED flash sequences on the platform controller. When operating nor-
mally the LED panel on the platform controller (center LED strip) indicates the battery voltage status using ten (10) green
LEDs. If a malfunction occurs to any of the drive components, the platform controller, or the MC-1 unit itself, these LEDs will
flash a fault code (Warning or Error type) to help locate the problem area. The possible causes of fault codes are outlined in
the following sub-sections of this chapter, see Table 3-1 and Table 3-2.
NOTE: For aid in troubleshooting electrical problem, refer to Figure 3-3. for an ELECTRICAL DIAGRAM of the various circuits.
Also a pictorial overview of the Section, see Figure 3-2. “Pictorial Overview of VP Electrical System”.