1995 ISUZU TROOPER Workshop Manual

2-2 TACHOMETER NEEDLE FLUCTUATES
(MAY
BE WIDE FLUCTUATION)
I· IS THE PULSE INPUT NORMAL? I
I
I
f YES l
I
I REPLACE THE TACHOMETER I
CHASSIS ELECTRICAL 8-299
I
NO j
l
THE WAVEFORM BY OSCILLOSCOPE IS DEFORMED. (ABNORMAL INPUT)
I
REPLACE THE DIS CONTROLLER, OR REPAIR A POOR
CONNECTION OF THE CONNECTORS IN THE CIRCUIT OR A FAILURE IN THE CABLE HARNESS
2-3 TACHOMETER NEEDLE JUMPS ERRATICALLY
I· IS THE PULSE INPUT NORMAL? I
I
I
I
I YES I NO j
I I
I REPLACE THE TACHOMETER I AN ABNORMAL PERIODIC WAVEFORM IS OUTPUT BY OSCILLOSCOPE
I
REPLACE THE IGNITON CONTROL MODULE, OR REPAIR A POOR CONNECTION OF THE CONNECTORS IN THE CIRCUIT OR A FAILURE IN THE HARNESS

8-300 CHASSIS ELECTRICAL
Inspection of a waveform by oscilloscope
1. Check the waveform of the meter assembly connector 3 ~ (Tachometer pulse).
I Normal waveform I
....---r---
MAX. 4.3V
~ -
MIN. 0.4V Engine revolution: 3000 rpm
I
6.7m sec.
'
ov
Fig. 8-341
..

CHASSIS ELECTRICAL 8-301
3. VOLTMETER
3-1 VOLTMETER NEEDLE DOES NOT MOVE ._..,
3-2 VOLTAGE READING IS TOO LOW {OR HIGH)
• IS THE METER ASSEMBLY CONNECTOR~ SECURELY CONNECTED?
I
YES I NO I
I
• DISCONNECT THE METER ASSEMBLY CONNECTORS~ AND(IiQJ
CONNECT THE CONNECTOR SECURELy I
• TURN ON THE STARTER SWITCH
• IS THE BATTERY VOLTAGE APPLIED BETWEEN THE HARNESS
SIDE CONNECTORS 14(m AND 4 ~ OF THE METER
ASSEMBLY?
I
YES I NO l
I
• IS THERE A OPEN CIRCUIT IN THE PRINTED CIRCUIT OF THE REPAIR A POOR CONNECTION OF THE CONNECTORS METER ASSEMBLY? OR A OPEN CIRCUIT IN T~IRCUIT BETWEEN THE
FUSE C-10 (10A) AND 14 1-9 I' OR THE CONNECTORS 4 [@] AND 4 C-39
I
YES ] NO I
I
REPLACE THE PRINTED CIRCUIT BOARD I CHECK THE VOLTMETER AND REPLACE IT A IF
NECESSARY (REFER TO THE CHECKING OF THE
VOLTMETER
IN THIS SECTION)

8-302 CHASSIS ELECTRICAL
4. ENGINE COOLANT TEMPERATURE (ECT) GAUGE
4-1 NEEDLE DOES NOT MOVE
• IS THE CONNECTOR OF THE THERMO UNIT CONNECTED SECURELY?
I
YES I
I NO l
I
• DISCONNECT THE CONNECTOR OF THE THEMO UNIT. I CONNECT THE CONNECTOR SECURELY I
• CONNECT A 3.4~B BETWEEN THE HARNESS SIDE CONNECTOR 1 E-19 AND THE GROUND OF THE THERMO
UNIT
• WHEN THE STARTER SW IS TURNED ON, DOES THE
ECT GAUGE POINTER MOVE ABOUT 10 SECONDS AFTER THAT?
I
YES I NO I
1
• IS THE THERMO UNIT NORMAL? I • IS THE CIRCUIT BETWEEN THE ECT GAUGE AND THE
THERMO UNIT NORMAL?
I I
YES I
I NO I I I
YES I l I NO
REPAIR A POOR CONNEC-I REPLACE THE THERMO UNIT I T T
TION AT THE CONNECTOR • IS THERE A BROKEN WIRE REPAIR A POOR CONNECTION
IN THE PRINTED CIRCUIT OF THE CONNECTORS OR A
OF THE METER ASSEMBLY? OPEN CIRCUIT IN THE CIRCUIT
I
I l
YES I NO I
I l
REPLACE THE PRINTED CHECK THE ECT GAUGE AND
CIRCUIT BOARD REPLACE IT WITH A CORRECT
ONE IF NECESSARY
•

CHASSIS ELECTRICAL 8-303
4-2 GAUGE READING ISTOO LOW (OR HIGH)
• DOES THE THERMOSTAT OPERATE NORMALLY? I
I
I
YES I NO I
I
• TURN THE STARTER SWITCH ON REPLACE THE THERMOSTAT I • WHEN INSERTING AND PULLING OUT THE THERMOSTAT
CONNECTOR 1 I E-191 SEVERAL TIMES, DOES THE INDICATION OF THE ECT GAUGE VARY?
I
I I
YES I NO I
I
REPAIR A POOR CONNECTION AT THE CONNECTOR • IS THE THERMO UNIT NORMAL? I OF THE THERMO UNIT
I
YES I NO I
I
• IS THERE A OPEN CIRCUIT IN REPLACE THE THERMO
THE METER ASSEMBLY UNIT
PRINTED CIRCUIT BOARD?
J
YES I NO I
I
REPLACE THE PRINTED CHECK THE ECT GAUGE,
CIRCUIT BOARD AND REPLACE IT IF
NECESSARY

8-304 CHASSIS ELECTRICAL
4-3 NEEDLE OVERSHOOTS (GOES UP TO THE 11H" RANGE)
• DISCONNECT THE CONNECTOR OF THE THERMO UNIT • WHEN THE STARTER SW IS TURNED ON, DOES THE
POINTER REACH TO THE "H" RANGE?
I
I I
YES I NO I
I I
• IS THERE
A SHORT CIRCUIT BETWEEN THE REPLACE
THE THERMO UNIT THERMO UNIT AND THE ENGINE COOLANT TEMPERATURE (ECT) GAUGE?
I
I
I
YES I NO I
I I
REPAIR THE SHORT CIRCUIT I • IS THE PRINTED CIRCUIT OF THE METER
ASSEMBLY GROUNDED SECURELY?
I
I l
YES I NO I
I I
CHECK
THE ECT GAUGE, REPAIR OR REPLACE THE PRINTED
AND REPLACE IT IF CIRCUIT BOARD
NECESSARY

5. OIL PRESSURE GAUGE
5-1 NEEDLE DOES NOT MOVE
• DISCONNECT THE CONNECTOR OF THE OIL PRESSURE UNIT
•
WHEN THE STARTER SW IS TURNED ON, DOES THE NEEDLE REMAIN STILL?
l
J I
YES I NO I
I I
CHASSIS ElECTRICAL 8-305
• IS THERE A SHORT CIRCUIT BETWEEN THE OIL REPLACE THE OIL PRESSURE UNIT I PRESSURE UNIT AND THE OIL PRESSURE GAUGE?
I
I I
YES I NO I
I l
REPAIR THE SHORT CIRCUIT I • IS THE PRINTED CIRCUIT OF THE METER ASSEMBLY GROUNDED SECURELY?
I
I I
YES I NO I
I I
CHECK THE OIL PRESSURE REPAIR OR REPLACE THE
GAUGE, AND REPLACE IT IF PRINTED CIRCUIT BOARD
NECESSARY

8-306 CHASSIS ELECTRICAL
5-2 OIL PRESSURE GAUGE READING IS TOO LOW (OR HIGH)
• (WHEN THE OIL PRESSURE IS MEASURED WITH THE MASTER METER)
DOES THE OIL PRESSURE GAUGE SHOWS THE CORRECT READING?
I
I
YES I NO I
I
• WHEN INSERTING AND PULLING OUT THE OIL CHECK FOR POSSIBLE ENGINE PROBLEM PRESSURE UNIT CONNECTOR 1 [IDSEVERAL TIMES, (REFER TO ENGINE SECTION) DOES THE INDICATION OF THE OIL PRESSURE GAUGE CHANGE?
I
I
YES I NO I
I
REPAIR A POOR CONNECTION AT THE CONNECTOR • IS THE OIL PRESSURE UNIT NORMAL? I OF THE OIL PRESSURE UNIT
I
YES J NO I
I
• IS THERE A OPEN CIRCUIT IN REPLACE THE OIL
THE PRINTED CIRCUIT BOARD PRESSURE UNIT
OF THE METER ASSEMBLY?
I
YES I NO I
I
REPLACE THE PRINTED CHECK THE OIL PRESSURE
CIRCUIT BOARD GAUGE, AND REPLACE IT
IF NECESSARY