Isuzu N-Series. Manual - part 898

Transmission Control System (Smoother) 7A-47

Engine Does Not Crank

Description
The Engine Does Not Crank diagnostic table is an
organized approach to identifying a condition that
causes an engine not crank. The diagnostic table directs
the service technician to the appropriate system
diagnosis. The diagnostic table assumes the following
conditions are met:

• The battery is completely charged and terminals

are cleaned and tight.

• Fuse and slow blow fuse are normal.

Diagnostic Aids

• If an intermittent condition is suspected, refer to

Intermittent Conditions in this section.

Test Description
The numbers below refers to the step number on the
diagnostic table.
7. This step checks whether the starter cut relay
command signal from TCM is canceled by the brake
pedal signal.

8. This step checks whether the starter cut relay
command signal from the TCM is canceled by the
parking brake signal from the ECM.
9. This step checks whether the starter cut relay
command signal from the TCM is canceled by the
emergency switch signal.
10. If the vehicle parked in gear, the starter cut relay
command is canceled by either of brake pedal, parking
brake or emergency switch input. This step retests with
the gear in neutral after engine is once started.

Engine Does Not Crank

Schematic Reference: Engine Controls Schematics
and Transmission Controls Schematics
Connector End View Reference: Engine Controls
Connector End Views, Engine Control Module (ECM)
Connector End Views, Transmission Controls
Connector End Views or Transmission Control Module
(TCM) Connector End Views

Chart 1 of 3

Step

Action

Value(s)

Yes

Did you perform the Diagnostic System Check -
Transmission Controls?

—

Go to Step 2

Go to Diagnostic

System Check -

Transmission

Controls

1. Install the Tech 2.
2. Turn OFF the ignition for 30 seconds.
3. Turn ON the ignition, with the engine OFF.
4. Monitor the Diagnostic Trouble Code (DTC)

Information with the Tech 2.

Is DTC P0602, P0605, P0613, P0851, P0852,
P0906, P0907 or P0914 set?

—

Go to Applicable

DTC

Go to Step 3

Operate the selector lever while observe the
Selector Position parameter with the Tech 2.

Does the Selector Position parameter indicate
correct position?

—

Go to Step 4

Refer to DTC P0906

and P0907

1. Put the vehicle with the following conditions:

• Selector lever N position
• Release the brake pedal
• Release the parking brake
• Emergency switch OFF

2. Attempt to start the engine.

Does the engine crank?

—

Go to Step 5

Go to Step 6

Does the engine start and idle?

—

System OK

Go to Engine Cranks

But Does Not Run in

Engine Control

Section

1. Turn ON the ignition, with the engine OFF.
2. Observe the Starter Cut Relay Command

parameter with the Tech 2.

Does the Starter Cut Relay Command parameter
indicate OFF?

—

Go to Chart 3 of 3

Step 1

Go to Step 7

7A-48 Transmission Control System (Smoother)

Put the vehicle with the following conditions:
• Selector lever N position
• Apply the brake pedal
• Release the parking brake
• Emergency switch OFF

Does the Starter Cut Relay Command parameter
indicate OFF?

—

Go to Step 8

Go to Chart 2 of 3

Step 1

Put the vehicle with the following conditions:
• Selector lever N position
• Release the brake pedal
• Apply the parking brake
• Emergency switch OFF

Does the Starter Cut Relay Command parameter
indicate OFF?

—

Go to Step 9

Go to Chart 2 of 3

Step 11

Put the vehicle with the following conditions:
• Selector lever N position
• Release the brake pedal
• Release the parking brake
• Emergency switch ON

Does the Starter Cut Relay Command parameter
indicate OFF?

—

Go to Step 10

Go to Chart 2 of 3

Step 16

1. Put the vehicle with the following conditions:

• Selector lever N position
• Apply the brake pedal or parking brake
• Emergency switch OFF

2. Start the engine. If the engine cranks but does

not start, go to Engine Cranks But Does Not
Run in the engine control section.

3. Set the gear position in neutral.
4. Stop the engine.
5. Put the vehicle with the following conditions:

• Selector lever N position
• Release the brake pedal
• Release the park brake
• Emergency switch OFF

6. Attempt to start the engine.

Does the engine crank?

—

Go to Step 5

Go to Step 11

Step

Action

Value(s)

Yes

Transmission Control System (Smoother) 7A-49

1. Visually inspect the gear shift position sensor

for the following conditions:

• Physical damage
• Loose or improper installation

2. Inspect the gear shift position sensor output

voltage.

Notice:
The gear shift position sensor voltage shifted to a
lower or a higher voltage will cause no engine crank
without DTC.

3. Remove the gear shift position sensor. Refer

to Gear Shift Position Sensor Replacement in
this section.

4. Visually inspect the gear shift position sensor

for the following conditions:

• Physical damage
• Loose or improper installation
• Shift lever damage that connects to the

gear shift position sensor shaft.

Did you find and correct the condition?

—

Go to Step 14

Go to Step 12

1. Turn OFF the ignition.
2. Disconnect the gear shift position sensor

harness connector.

3. Inspect for an intermittent, for poor

connections and corrosion at the harness
connector of the gear shift position sensor
(pins 1, 2 and 3 of J-142 connector).

4. Disconnect the TCM harness connector.
5. Inspect for an intermittent, for poor

connections and corrosion on each gear shift
position sensor circuit at the harness
connector of the TCM (pins 18, 19 and 20 of B-
426 connector).

6. Test for high resistance on each gearshift

position sensor circuit.

7. Repair the connection(s) or circuit(s) as

necessary.

Did you find and correct the condition?

—

Go to Step 14

Go to Step 13

Important:
Replacement gear shift position sensor must be
relearned.
Replace the gear shift position sensor. Refer to
Gear Shift Position Sensor Replacement in this
section.

Did you complete the replacement?

—

Go to Step 14

—

Step

Action

Value(s)

Yes

7A-50 Transmission Control System (Smoother)

Chart 2 of 3

1. Reconnect all previously disconnected

harness connector(s).

2. Clear the DTCs with the Tech 2 if stored.

Important:
Transmission Gear Select & Shift Position Learning
must be done if the gear shift position sensor or
transmission gearshift control box is replaced,
removed or repaired.

3. Turn OFF the ignition for 30 seconds.
4. Put the vehicle with the following conditions:

• Selector lever N position
• Release the brake pedal
• Release the parking brake
• Emergency switch OFF

5. Attempt to start the engine.

Does the engine crank?

—

Go to Step 5

Go to Step 2

Step

Action

Value(s)

Yes

Step

Action

Value(s)

Yes

1. Check to ensure the brake pedal switch is

adjusted correctly. The plunger should be all
the way in when the pedal is released, yet
should not impede with the brake pedal full
upward travel.

2. Adjust the brake pedal switch as necessary.

Did you find and correct the condition?

—

Go to Step 25

Go to Step 2

1. Turn OFF the ignition.
2. Inspect the Stop Light (10A) fuse (F-5) in the

glove box fuse block.

Is the Stop Light (10A) fuse (F-5) open?

—

Go to Step 3

Go to Step 4

Replace the Stop Light (10A) fuse (F-5). If the fuse
continues to open, repair the short to ground on one
of the circuits that is fed by the Stop Light (10A) fuse
(F-5) or replace the shorted attached component
fed by the Stop Light (10A) fuse (F-5).

Did you complete the repair?

—

Go to Step 25

—

1. Turn OFF the ignition.
2. Disconnect the brake pedal switch harness

connector.

3. Connect a test lamp between the voltage feed

circuit of the brake pedal switch harness (pin 1
of B-66 connector) and a known good ground.

Does the test lamp illuminate?

—

Go to Step 5

Go to Step 6

1. Turn ON the ignition, with the engine OFF.
2. Observe the Brake Pedal Switch parameter

with the Tech 2 while momentarily jumping 3-
amp fused jumper wire across the brake pedal
switch harness connector between pins 1 and
2 of the B-66 connector.

Does the Tech 2 indicate Applied when the circuit is
jumpered and Released when the circuit is not
jumpered?

—

Go to Step 8

Go to Step 7

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