Isuzu KB P190. Manual - part 36

1-110  HEATER AND AIR CONDITIONING 

MAGNETIC CLUTCH DOES NOT RUN (4JJ1-TC Standard Output, 4JJ1-TC 

High Output, 4JK1-TC High Output LHD MODEL) 
 

 
 

Replace 

YES 

• Are the A/C thermo (X-15), heater & A/C (X-11) and 
A/C compressor (X-14) relay OK? 

• Are the No. SBF-6 fuse (30A) and the No. EB-13 
(10A) fuses OK? 

YES 

• Is the pressure switch (C-24) OK? 

YES 

• Are the A/C switch (B-57) and the fan switch (B-13) 
OK? 

NO 

YES 

• Is there continuity between the engine harness 
connector terminal No.1 (E-3) and the engine room 
harness connector terminal No.2 (X-14)? 

• Disconnect the A/C compressor relay. 

• Turn the ignition switch "ON" (Engine is running) 

• A/C switch and fan control knob (fan switch) "ON" 

NO 

Replace 

NO 

Defective switch or insufficient 
refrigerant 

NO 

NO 

Does the magnetic clutch 
operate? 

YES

Replace 

• Disconnect the magnetic clutch connector. 

• Is there battery voltage between the engine room 
harness connector terminal No.1 (E-3) and ground? 

Defective compressor  

YES

NO 

Defective magnetic clutch  

• Is the electronic thermostat (C-55) OK? 

YES 

Replace 

NO 

 

HEATER AND AIR CONDITIONING  1-111 

 

 
 
 

Open circuit between the engine 
harness connector terminal No.1 (E-3) 
and the engine room harness 
connector terminal No.2 (X-14). 

YES 

• Is there battery voltage between the engine room 
harness connector terminal No.1 (X-14) and 
ground? 

YES 

• Disconnect the A/C thermo relay. 

YES 

• Is there continuity between the ECM harness 
connector terminal No.55 (C-58) and the engine 
room harness connector terminal No.5 (X-14)? 

NO

Open circuit between the No. EB-13 
fuse and the engine room harness 
connector terminal No.1 (X-14). 

NO

Open circuit between the engine room 
harness connector terminal No.3 (X-
14) and the engine room harness 
connector terminal No. 1 (X-15). 

NO

• Is there continuity between the engine room 
harness connector terminal No.3 (X-14) and the 
engine room harness connector terminal No.1 (X-
15)? 

YES 

• Is there continuity between the ECM harness 
connector terminal No.4 (C-58) and the engine 
room harness connector terminal No.1 (X-15)? 

Open circuit between the ECM 
harness connector terminal No.55 (X-
58) and the engine room harness 
connector terminal No. 5 (X-14). 

NO

YES 

• Is there battery voltage between the engine room 
harness connector terminal No.2 (X-15) and 
ground? 

Open circuit between the ECM 
harness connector terminal No. 4 (C-
58) and the engine room harness 
connector terminal No. 1 (X-15). 

NO

YES 

• Is there continuity between the engine room 
harness connector terminal No. 5 (X-15) and the 
engine room harness connector terminal No. 1 (C-
24)? 

Open circuit between the No. EB-13 
fuse and the engine room harness 
connector terminal No. 2 (X-15). 

NO

• Disconnect the ECM harness connector. 

• Disconnect the pressure switch. 

 

 

1-112  HEATER AND AIR CONDITIONING 

 

 
 

YES 

• Disconnect the condenser fan relay. 

YES 

• Is there battery voltage between the engine 
room harness connector terminal NO.3 (C-
24) and ground? 

Open circuit between the condenser 
fan relay No.3 (X-9) and the engine 
room harness connector terminal No. 
4 (C-24). 

NO

• Is there continuity between the relay terminal 
No. 3 (X-9) and engine room harness connector 
terminal No.4 (C-24)? 

YES 

Open circuit between the No. EB-13 
fuse and engine room harness 
connector terminal No. 3 (C-24). 

NO

YES 

• Is there battery voltage between the engine 
room harness connector terminal No.3 (C-55) 
and ground? 

Open circuit between the engine room 
harness connector terminal No. 2 (C-
24) and the engine room harness 
connector terminal No. 2 (C-55). 

NO

YES 

• Is there continuity between the engine room 
harness connector terminal No.1 (C-55) and 
ground (C-109)? 

Open circuit between the No. EB-13 
fuse and the engine room harness 
connector terminal No. 3 (C-55). 

NO

• connect the A/C thermo relay connector. 

• Disconnect the electronic thermostat. 

• Is there continuity between the engine room 
harness connector terminal No. 2 (C-55) and the 
engine room harness connector terminal No. 2 
(C-24)? 

Open circuit between the engine room 
harness connector terminal No. 5 (X-
15) and the engine room harness 
connector terminal No. 1 (C-24). 

NO

 

HEATER AND AIR CONDITIONING  1-113 

 

 

YES 

• Is the electronic thermostat OK? 

Open circuit between the engine room 
harness connector terminal No. 1 (C-55) 
and ground (C-109). 

NO 

YES 

• Disconnect the A/C switch. 

• Is there battery voltage between the chassis side 
harness connector terminal No. 6 (B-57) and ground? 

Open circuit between the No. EB-13 fuse 
and the chassis side harness connector 
No. 6 (B-57)  

NO 

YES 

• Defective ECM 

Replace electronic thermostat 

NO