Isuzu N-Series. Service manual - part 431

6E-60 EMISSION AND ELECTRICAL DIAGNOSIS

DTC-P23 Solenoid Switch Control Circuit Low Voltage

N6A1173E

EMISSION AND ELECTRICAL DIAGNOSIS 6E-61

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-62 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

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”, Engine “ON”.
2. Jumper the magnetic switch Relay ground

circuit at the Relay connector to chassis
ground.

3. Observe the “Relay; solenoid switch” cir-

cuit open status on the scan tool.

Has DTC23 been corrected?

—

Go to Step 4

Go to Step 3

3

1. Check for poor connector at the Relay

connector and replace the terminals if
necessary.

Did any terminals require replacement?

—

Go to Step 11

Go to Step 5

4

1. Check the Relay ground circuit for an

open.

2. If the Relay ground circuit is open, repair

it as necessary.

Was the Relay ground circuit open?

—

Go to Step 11

Go to Step 2

EMISSION AND ELECTRICAL DIAGNOSIS 6E-63

5

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

ed.

2. Disconnect the Solenoid switch Relay

connector.

3. Apply a circuit tester with voltage range or

a test light to the output line for the Relay.

4. Ignition “ON”, Measure the voltage or

check the test light “ON”. Ignition “OFF”

≥8V or light 

“ON” (for 12 

Volt)

≥16V or light 

“ON” (for 24 

Volt)

Go to Step 8

Go to Step 6

6

1. Ignition “ON”.
2. Disconnect ECM, and check for the Relay

signal circuit terminal connector at the
ECM and clean or replace terminal if nec-
essary.

Did any terminals need to be repaired?

—

Go to Step 11

Go to Step 7

7

1. Check the Relay signal circuit for an open.
2. If the Relay signal circuit is open, repair it

as necessary.

Was the Relay signal circuit open?

—

Go to Step 11

Go to Step 8

8

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

circuit terminals of the Relay.

Is the resistance within specific value?

240 — 290

Ω 

(for 12 Volt)

256 — 276

Ω 

(for 24 Volt)

Go to Step 10

Go to Step 9

9

1. Replace the Relay.

Is the action complete?

—

Go to Step 11

—

10

1. Replace the ECM

Is the action complete?

—

Go to Step 11

—

11

1. Reconnect all the connectors removed.
2. Ignition “ON”, Engine “OFF”.
3. Ignition “OFF” after 30 seconds.
4. Install Scan tool.

Is DTC 23 all right under Scan Tool Check?

—

Go to Step 12

Go to Step 2

12

Is any current trouble other than DTC 23 dis-
played by scan tool?

—

Go to trouble code 

section

Trouble code clear

Step

Action

Value

YES

NO