Isuzu N-Series. Service manual - part 451

6E-140 EMISSION AND ELECTRICAL DIAGNOSIS

Quick Warm System (QWS) Malfunction

N6A1676E

EMISSION AND ELECTRICAL DIAGNOSIS 6E-141

N6A1276E

6E-142 EMISSION AND ELECTRICAL DIAGNOSIS

Inspection

1. Exhaust Throttle Valve

Working Check

Actuate the exhaust brake with the engine idling
and make sure that you hear the valve strike on the
stopper.

Airtight Check

Apply a negative pressure of -53.3 — -93.3 kPa (-
400 — -700 mmHg/-7.73 — -13.54 psi) to the pow-
er chamber by means of a vacuum pump and
make sure of the smooth opening/closing of the ex-
haust brake valve.

Apply a negative pressure of -86.7 — -93.3 kPa (-
650 — -700 mmHg/-12.57 — -13.54 psi) to the
power chamber using a vacuum pump and make
sure the average of measurements at Point A and
Point B of the clearance between valve and body is
as follows:
0.4 — 0.6 mm (0.016 — 0.024 in) (Minimum: 0.4
mm/0.016 in)
If the clearance is out of this range adjust with the
adjusting bolt.

2. Intake Throttle Valve

Working Check

Disconnect the vacuum hose from the actuator and
try to move the rod by hand, making sure of the
smooth move of the rod.

3. Exhaust Brake Magnetic Valve

Inspection

Connect the magnetic valve connector terminal
No.1 and No.2 to (+) terminal and (-) terminal of
battery respectively, and check the continuity be-
tween the ports.

N6A1248E

Legend

1. Power chamber
2. Adjust bolt
3. Valve
4. Close

Legend

1. Vacuum hose

N6A1249E

N6A1250E

EMISSION AND ELECTRICAL DIAGNOSIS 6E-143

4. Accelerator Switch (2-pole connector type)

Inspection

1) Check the continuity between the switch con-

nector terminals.

2) Check the smooth move of the pushrod. If the

check result is abnormal, repair or replace the
pushrod.

Caution:
When measuring resistance with a circuit tester, be
careful not to damage or deform the terminals.

Removal

1) Accelerator Switch 

Disconnect the connector. 
Loosen the lock nut. 
Turn the switch to remove.

Reinstallation
To install, follow the removal procedure in reverse order:

1) Drive the threaded part of the switch until its

end surface becomes flush with that of the
bracket side of nut.

2) Tighten the lock nut.

Tightening torque: 1.3 N

⋅m (0.13 kg⋅m/11.5

lb

⋅in)

5. Thermosensor (Engine coolant temperature)

Soak the temperature sensitive part of a ther-
mosensor in the water, and while changing the wa-
ter temperature, make sure the resistance is
changed as the following graph shows:

Legend

A. Inlet (vacuum pump)
B. Outlet (unit)

C. EXH (air filter)

N6A1247E

N6A1252E