Isuzu N-Series. Manual - part 432

6E-64 EMISSION AND ELECTRICAL DIAGNOSIS

DTC-P24 Solenoid Switch Control Circuit High Voltage

N6A1173E

EMISSION AND ELECTRICAL DIAGNOSIS 6E-65

Location of Relay

Inspection for Timing Advance Solenoid Switch cut
relay

Legend

1. Relay box (Installed on the instrument panel)

N6A1174E

NO

RELAY NAME

X-5

ABS IND.

X-6

Dimmer

X-7

Power window

X-8

Exh. brake

X-9

Cornering lamp

X-10

Thermo A/C

X-11

Exh. Brake, Charge warning, Key ON

X-12

Heater & A/C

X-13

Buzzer cancel, Heater

X-14

ECU, PTO main, Timing

X-15

Tail, PTO solenoid, M/T

X-16

PTO cut

Legend

A. Timing advance solenoid

N6A1175E

6E-66 EMISSION AND ELECTRICAL DIAGNOSIS

Resistance value

N6A1176E

N6A1177E

Inspection Point

Resistance

Reference

Inspection 
relay unit

2 

←→ 4

240 to 290 (

Ω) (for 12 volt)

256 to 276 (

Ω) (for 24 volt)

1 

←→ 5

∞

Not be supplied electricity

Below 0.5 (

Ω)

Be supplied electricity

3 

←→ 5

Below 0.5 (

Ω)

Be supplied electricity

∞

Not be supplied electricity

EMISSION AND ELECTRICAL DIAGNOSIS 6E-67

Step

Action

Value

YES

NO

1

Was the “on-board diagnostic (OBD) system
check” performed?

—

Go to Step 2

Go to self diag 

system check

2

1. Ignition “OFF”, with scan tool disconnect-

ed.

2. Disconnect the Relay solenoid switch

from the Relay box.

3. Apply a circuit tester with the voltage

range or a test light to the output circuit for
the Relay.

4. Ignition “ON”, Engine “OFF”.

Is voltage as prescribed, or is test Light lit until
18 seconds?

≥8V or light 

“ON” (for 12 

Volt)

≥16V or light 

“ON” (for 24 

Volt)

Go to Step 6

Go to Step 3

3

1. Ignition “OFF”.
2. Check if there is no short between Relay

Box Terminals.

3. Repair if necessary.

Was the circuit shorted between Relay Box
Terminals?

—

Go to Step 8

Go to Step 4

4

1. Disconnect the ECM.
2. Check if Relay Sig Circuit for a short to

Chassis/GND or short to voltage.

3. Repair if necessary.

Was Relay signal circuit shorted?

—

Go to Step 8

Go to Step 5

5

1. Disconnect the Relay.
2. Measure the resistance between the coil

circuit terminal of the Relay.

Is the resistance with in specific valve?

240 — 290

Ω 

(for 12 Volt)

256 — 276

Ω 

(for 24 Volt)

Go to Step 8

Go to Step 6

6

1. Ignition “OFF”.
2. Replace the Relay.

Is the action complete?

—

Go to Step 8

—

7

1. Ignition “ON”.
2. Replace the ECM.

Is the action complete?

—

Go to Step 8

—

8

1. Reconnect all the connectors removed.
2. Ignition “ON”, Engine OFF, and Ignition

off after 30sec.

3. Install Scan tool.
4. Ignition “ON”, Engine “OFF”.

Is DTC 24 all right under Scan Tool Check?

—

Go to Step 9

Go to Step 2

9

Is any current trouble other than DTC 24 dis-
played by scan tool?

—

Go to trouble code 

section

Trouble code clear