Isuzu N-Series. Manual - part 721

6E-306 Engine Control System (4HK1)

Test the exhaust brake switch signal circuit
between the engine control module (ECM)
(pin 45 of J-191 connector) and the exhaust
brake switch (pin 2 of B-69 connector) for a
short to battery or ignition voltage.

Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 30

Go to Step 29

Turn OFF the ignition.

Inspect the Fuel Heater (10A) fuse in the
glove box fuse block.

Is the Fuel Heater (10A) fuse open?

—

Go to Step 6

Go to Step 7

Replace the Fuel Heater (10A) fuse. If the fuse
continues to open, repair the short to ground on
one of the circuits that fed by the Fuel Heater (10A)
fuse or replace the shorted attached component
fed by the Fuel Heater (10A) fuse.

Did you complete the repair?

—

Go to Step 30

—

Turn OFF the ignition.

Disconnect the exhaust brake switch B-69
harness connector (located on the steering
column support bracket).

Connect a test lamp between the voltage feed
circuit of the exhaust brake switch harness
(pin 5 of B-69 male side connector) and a
known good ground.

Start the engine.

Does the test lamp illuminate?

—

Go to Step 8

Go to Step 9

Observe the Exhaust Brake Switch parameter
with the Tech 2 while momentarily jumping 3-
amp fused jumper wire across the exhaust
brake switch harness connector between pins
2 and 5 of the B-69 connector.

Does the Tech 2 indicate ON when the circuit is
jumpered and OFF when the circuit is not
jumpered?

—

Go to Step 11

Go to Step 10

Repair the open circuit or high resistance on the
voltage feed circuit between the Fuel Heater (10A)
fuse and the exhaust brake switch (pin 5 of B-69
connector).

Did you complete the repair?

—

Go to Step 30

—

Test the exhaust brake switch signal circuit
between the ECM (pin 45 of J-191 connector)
and the exhaust brake switch (pin 2 of B-69
connector) for an open circuit or high
resistance.

Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 30

Go to Step 12

Step

Action

Value(s)

Yes

Engine Control System (4HK1) 6E-307

Turn OFF the ignition.

Inspect for an intermittent and for poor
connections at the harness connector of the
exhaust brake switch (pins 2 and 5 of B-69
connector).

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 30

Go to Step 13

Turn OFF the ignition.

Disconnect for an intermittent and for a poor
connection on the exhaust brake switch signal
circuit at the harness connector of the ECM
(pin 45 of J-191 connector).

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 30

Go to Step 29

Repair or Replace the exhaust brake switch.

Did you complete the replacement?

—

Go to Step 30

—

Turn OFF the ignition.

Inspect the Meter (10A) fuse in the glove box.

Is the Meter (10A) fuse open?

—

Go to Step 15

Go to Step 17

Replace the Meter (10A) fuse. If the fuse continues
to open, repair the short to ground on one of the
circuits that is fed by the Meter (10A) fuse or
replace the shorted attached component fed by the
Meter (10A) fuse.

Did you complete the repair?

—

Go to Step 30

—

Turn OFF the ignition.

Disconnect the ECM J-191 harness
connector.

Turn ON the ignition, with the engine OFF.

Is the exhaust brake indicator lamp OFF?

—

Go to Step 29

Go to Step 24

Turn OFF the ignition.

Remove the Meter (10A) fuse that supplies
voltage to the exhaust brake indicator lamp.

Disconnect the ECM J-191 harness
connector.

Turn ON the ignition, with the engine OFF.

Measure the voltage from the exhaust brake
indicator lamp control circuit in the ECM
harness connector (pin 7 of J-191 connector)
to a good ground.

Is the voltage less than the specified value?

1 volt

Go to Step 18

Go to Step 25

Turn OFF the ignition.

Install the Meter (10A) fuse that supplies
ignition voltage to the exhaust brake indicator
lamp.

Turn ON the ignition, with the engine OFF.

Connect a 3-amp fused jumper wire between
the exhaust brake indicator lamp control
circuit of the ECM harness connector (pin 7 of
J-191 connector) and a known good ground.

Is the exhaust brake indicator lamp illuminated?

—

Go to Step 23

Go to Step 19

Step

Action

Value(s)

Yes

6E-308 Engine Control System (4HK1)

Turn OFF the ignition.

Remove the instrument panel cluster (IPC).

Remove the exhaust brake indicator lamp
bulb from the IPC.

Is the exhaust brake indicator lamp bulb burned
out?

—

Go to Step 27

Go to Step 20

Connect a test lamp between the exhaust
brake indicator lamp ignition voltage circuit of
the IPC harness connector (pin 18 of B-51
connector) and a known good ground.

Turn ON the ignition, with the engine OFF.

Does the test lamp illuminate?

—

Go to Step 21

Go to Step 26

Test the exhaust brake indicator lamp control
circuit between the ECM (pin 7 of J-191
connector) and the IPC (pin 6 of B-51
connector) for an open circuit or high
resistance.

Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 30

Go to Step 22

Turn OFF the ignition.

Inspect for an intermittent and for poor
connections at the harness connector of the
IPC (pins 6 and 18 of B-51 connector).

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 30

Go to Step 28

Turn OFF the ignition.

Disconnect the ECM harness connector.

Inspect for an intermittent and for a poor
connection on the exhaust brake indicator
lamp control circuit at the harness connector
of the ECM (pin 7 of J-191 connector).

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 30

Go to Step 29

Repair the short to ground on the control circuit of
the exhaust brake indicator lamp between the ECM
(pin 7 of J-191 connector) and the IPC (pin 6 of B-
51 connector).

Did you complete the repair?

—

Go to Step 30

—

Repair the short to battery or ignition voltage on the
control circuit of the exhaust brake indicator lamp
between the ECM (pin 7 of J-191 connector) and
the IPC (pin 6 of B-51 connector).

Did you complete the repair?

—

Go to Step 30

—

Repair the open or high resistance on the voltage
feed circuit of the exhaust brake indicator lamp
between the Meter (10A) fuse and the IPC (pin 6 of
B-51 connector).

Did you complete the repair?

—

Go to Step 30

—

Replace the exhaust brake indicator lamp bulb.

Did you compete the replacement?

—

Go to Step 30

—

Step

Action

Value(s)

Yes

Engine Control System (4HK1) 6E-309

Repair or replace the IPC.

Did you complete the repair or replacement?

—

Go to Step 30

—

Important:
Replacement ECM must be programmed.

Replace the ECM. Refer to Engine Control Module
(ECM) Replacement / Fuel Injector ID Code Data
Programming in this section.

Did you complete the replacement?

—

Go to Step 30

—

Reconnect all previously disconnected fuse or
harness connector(s).

Is the action complete?

—

Go to Chart 1 of 2

Step 2

—

Step

Action

Value(s)

Yes

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