LAUNCH                                                    X-431 PAD III User Manual 
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converting cable. 
*Note: Choose corresponding cables and test probes according to different terminals. 
9.3.2 Simulation test 
Simulation  test  enables  users  to  exactly  judge  if the  sensor  is  good  or  not  to 
avoid replacing components blindly. For example, the trouble code indicates the 
fault is in water temperature sensor itself. But we need to confirm whether the 
fault  results  from  water  temperature  sensor  or  the  connections  between  ECU 
and sensors, or ECU itself. In this case, we can make full use of simulation test 
to  input  the  signal  of  simulating  water  temperature  sensor,  instead  of  water 
temperature  sensor,  to  the microcomputer.  If the engine  works  better  and  the 
fault vanishes, the fault is in the water temperature sensor. If the fault still occurs, 
input the signal to the corresponding terminals of ECU. Consequently, if the fault 
disappears,  the fault lies in the connection between water temperature sensor 
and ECU, otherwise, the fault exists in ECU. 
After all connections are properly made (refer to Chapter 9.3.1 for details), turn 
the tablet on and enter the Home screen, then tap “Toolbox” -> “Sensor” to enter 
the test selection screen. See Fig. 9-2. 
   
Fig. 9-2 
1. DC voltage simulation 
In Fig. 9-2, tap [Current voltage], then tap “+” or “-” to adjust the output voltage 
value. Alternatively, user can also tap edit box, then use the on-screen keyboard 
to input the desired value directly. After selecting or inputting the desired voltage 
based  on  the  working  characteristics  of  sensor,  tap  the    button,  then  the 
X-431 PAD III will begin to output the simulation voltages. Please note the red