Isuzu KB P190. Manual - part 903

Starting System – V6 

Page 6D1-2–4 

 

• 

Clarify a procedure, 

• 

Present additional information for accomplishing a procedure, 

• 

Give insight into the reasons for performing a procedure in the recommended manner, and / or 

Present information that gives the technician the benefit of past experience in accomplishing a procedure with greater 
ease. 

1.2  

Components 

Starting System Components 

The main components of the starting system are: 

• 

battery, 

• 

wiring, 

• 

ignition switch, 

• 

theft deterrent engine crank inhibitor (a function of the theft deterrent system), 

• 

park / neutral and back-up switch (on vehicles with 4 speed automatic transmission), 

• 

engine control module (ECM), 

• 

start relay, 

• 

solenoid switch, and 

• 

starter motor. 

Starter Motor and Solenoid Switch Components 

Solenoid Switch 

The solenoid switch is used to activate the DC motor and has two windings; the pull-in winding and the hold-in winding. 
The pull-in winding has heavier wire and is grounded through the DC motor winding and brushes. The hold-in winding is 
grounded through the solenoid casing. 

Planetary Drive Train 

The planetary drive train consists of an internally toothed ring gear and three planetary gear wheels, which rotate on 
sleeve bearings on the planetary drive shaft. The ring gear is keyed into the drive-end housing and is made from 
high-grade polyamide with mineral additives. 

When the starter motor operates, the armature turns the planetary gears inside the fixed planetary ring gear. This drives 
the planetary shaft at a reduced speed ratio which turns the drive assembly. A fork lever in the drive-end housing forces 
the drive assembly forward to engage with the flexplate / flywheel ring gear on the engine and transmit cranking torque. 

An internal clutch allows the drive assembly pinion gear to rotate freely when the engine starts. This prevents the 
armature from being driven at excessive speed by the engine. 

Armature 

The armature shaft is supported at each end by oil absorbent, sintered metal bushes; one in the commutator end shield 
and one in the planetary drive shaft. The front end of the armature has a gear profile. This meshes with the three 
planetary gear wheels. These in turn, mesh with the internal teeth of the ring gear. 

Brushes 

A brush plate supports four commutator brushes. This plate is fixed to the commutator end shield with two retaining 
screws. Two negative brushes are grounded to the pole housing. The two positive brushes are insulated from the pole 
housing and connected to the solenoid switch M terminal, refer to Figure 6D1-2 –  1. 

Starting System – V6 

Page 6D1-2–5 

 

 

Figure 6D1-2 –  1 

Legend 

1 Solenoid 

Switch 

1 Starter 

Motor 

3 

Starter Motor terminal M 

4 Connector 

P-4 

5 

Connector P-3 –  pin 1 

1.3 System 

Operation 

Operation 

The ECM controls the activation of the start relay in response to inputs from: 

• 

ignition switch, 

• 

battery, 

• 

theft deterrent engine crank inhibitor (a function of the theft deterrent system), 

• 

park / neutral and back-up switch (on vehicles with 4 speed automatic transmission), 

The start relay controls the operation of the start solenoid. 

The start solenoid controls operation of the starter motor and the drive assembly. 

Starting System – V6 

Page 6D1-2–6 

 

Sequence of Operation 

1 

When the ignition switch is turned to the START position, a signal is also sent to the ECM to request the engine to 
crank. 

• 

For automatic vehicles the transmission must be in either park (P) or neutral (N) for the ECM to allow 
cranking to commence. 

• 

The ECM will only allow cranking if the battery voltage is above the minimum battery voltage threshold value, 
refer to 6C1-1 Engine Management – V6 – General Information for further information. 

2 

The ECM operates the start relay which provides power to the pull-in winding of the start solenoid. 

3 

Current flow to the pull-in winding develops powerful magnetism which pulls in the solenoid switch plunger. 

4 

The plunger closes the switch contacts connecting battery voltage to the DC motor and pivots the fork lever to 
engage the drive assembly to the flexplate / flywheel ring gear. Closing the solenoid switch contacts deactivates the 
pull-in winding, the hold-in winding remains active. 

5 

With the solenoid switch contacts closed, current flows from the battery through the DC motor, which rotates the 
armature at high speed and provides cranking torque. 

 

 

 

 

 

 

 

 

  

 

 

Starting System – V6 

Page 6D1-2–7 

 

2 Diagnostics 

2.1 

Diagnostic General Information 

N O T E  

There is a minimum battery voltage threshold 
value. If the battery voltage is below the set value, 
the ECU will inhibit cranking. Refer to 6C1-1 
Engine Management – V6 – General Information 
for further information. 

Basic Diagnostic Tools Required 

 

Use of incorrect electrical circuit diagnostic 
tools when performing the cruise control 
diagnostic procedures could result in 
incorrect diagnostic results or damage to 
components. 

The following electrical circuit testing tools are required to perform the diagnostic procedures detailed in this Section:  

• 

digital multimeter with 10 meg ohms impedance, and 

• 

connector test adapter kit Tool No. KM609. 

For further information on the use of these tools, refer to 8A Electrical Body and Chassis. 

2.2 

Tech 2 Data List 

The Tech 2 displays the status of certain starting system parameters. 

To view the data list: 

1 

Connect Tech 2 to the DLC. 

2 

On Tech 2 select: 
Engine / V6 Engine / Data Display / Data List / Electrical / Theft Data. 

Tech 2 Parameter 

Units Displayed 

Typical Display Values

Crank Request 

Inactive / Active 

Inactive 

Starter Relay 

Off / On 

Off 

2.3 

Diagnostic Systems Check 

Step Action 

Yes 

No 

1 

Is the fault specifically isolated to this system / module? 

Go to Step 2 

Go to 0D Vehicle 

Diagnostics 

2 

1 

Connect Tech 2 to the DLC. 

2 

Ignition ON, engine OFF. 

3 

On Tech 2 select: 
Engine / V6 Engine / Diagnostic Trouble codes / Read 
DTC’s. 

Are there any set DTC’s? 

Go to the 

appropriate DTC 

table in 6C1-2 

Engine 

Management – V6 – 

Diagnostics. 

Refer to 2.5

 Starting 

System Inoperative / 

Malfunctioning