97 

 

Idle speed actuator step motor 

 

 
 

 

 

98 

Maintenance precautions: 

1. Do not apply any forces axially to press down or take out the axle;   

Before idle speed governor with stepper motor is installed within throttle valve body, the axle 
must be at completely holdback position;   

3. Pay attention to cleaning of bypass air route;   

4. After removing battery cell, manually trigger self-learning function of stepper motor duly by 
using K line for malfunction diagnosis for earthing with three times, and earthing time equaling to 
and larger than 2.5s each time, or self-learning by using diagnosis instrument;   

Simple measuring method: 

1. (Remove the connector) place digital multimeter to ohm position, and two pens are 
respectively connected into AD, BC pins of regovernor, and rated resistance under 25  is 

℃

53±5.3Ω; otherwise, replace it;   

2. (Connect the connector) Start the engine, and make it rotate under idling speed; put hands 
slightly against stepper motor, and you feel slight vibration at this point;   

3. Read amount of step of idle speed stepper motor out of engine parameter with diagnosis 
instrument, and start the air conditioner, and amount of step will increase. If rotating speed of the 
engine is kept at 3000rpm for a certain time, check amount of step will continue to rise, till to 
maximum opening value, which indicates that stepper motor is working normally;   

4. If you cannot make judgment, recommend malfunction recurrence testing on malfunction-free 
vehicle;  

 
 

 

 

99 

Diagnosis flowchart of idling speed stepper motor 

 

1. Switch on diagnosis instrument, and start the engine, and observe its 
idling speed is stable? Observe stepper motor is within normal working 
range through idling speed status of diagnosis instrument? 

3. Check control lines of stepper motor are with the following conditions? 
Socket connector is tightly inserted or loosening; open circuited; shorted 
to ground or shorted to voltage source; joint of stepper motor falls out. 

2. Check bypass opening is clean and not obstructed?   

4. Check resistance of stepper motor coil is within 35-95ohm? 
Note: this value is related to temperature.   

5. Check resistance between terminal B and D, and A and C of idling 
speed stepper motor is infinitely large?   

6. Check joint terminal and earthing resistance is larger than 
10000ohm?  

7. Clean idling speed bypass opening with compressed air gun; drive 
stepper motor with idling-speed initialization function of diagnosis 
instrument, making valve stem slide to clean pollutants with compressed 
air; confirm repairs are completed.   

8. Replace idling-speed control stepper motor; confirm repairs are 
completed?  

9. Replace ECU, and confirm repairs are completed?   

Repair  

Y 

Y 

Y 

Y 

Y

Y 

Y 

N 

N 

N 

N 

N 

N

 
 

 

 

100 

 

No.057 Quick diagnosis for ignition coil   

Function: transform low-voltage direct current of the battery into high-voltage, and generate 
spark through discharging of spark plug, causing gas mixture within the cylinder.   
Principle: when earthing channel of primary winding is switched on, this winding is charged. If 
circuits of primary winding are cut off by ECU, then charging is terminated, and meanwhile, high 
voltage is inducted from secondary winding, making spark plug discharge. What is different from 
ignition coil with distributor is that, secondary winding of ignition coil ZSK2 2 has spark plug each 
connected to its two terminals, and these two plugs will ignite at the same time.

 

 

Ignition coil ZSK-ROV has two pins at its low-voltage sides:   
Pin with “+” is connected with the battery, and pin with “-” with ECU1#; High voltage side: 
connected to center of distributor   

 

Double-spark ignition coil 

Ignition switch #90 

Ignition switch #90 

ignition coil