1#：K line； 2#：K line；
3#：K line； GND：Ground wire（negative）；
7#：RSR232+, J1708+, K line；8#：K line；
9#：K line； 10#：K line；
11#：K line； 12#：K line；
13#：K line； 14#：CAN‐L；
15#：RSR232‐, K line, J1708‐, L line
VCC: power line（Positive）； POWER：Power indicator.
Remark: If lack of vehicle electrical equipment knowledge or unable to confirm electrical equipment power supply, please don’t operate jumper, for error operation of jumper may lead to malfunction of electrical failure or FCAR F3-D main unit and wire.
(Auto diagnostic socket related information reconfirmed as below)
● Digital high impedance multimeter (can not use Analog Multimeter)
● When ignition switch to ON Gear, there is supply voltage of vehicle on diagnostic socket. Voltage difference between voltage on diagnostic socket and vehicle battery side can not be above 2.5V.
In diagnosis, if the signal line used is single-line communication (K line), voltage on signal line lower than battery voltage,(if vehicle supply voltage is 12V,then voltage on signal line is 11V, + 0.25V;if 24V,signal voltage is 21V,+ 0.25V)
If double signal line adopts CAN communication, 2 diagnostic lines use multimeter to measure ground wire voltage under the condition that ignition switch open, the sum of both voltages is 5V,average 2.5V,the one voltage little higher than 2.5V is CAN-H, the one voltage lower than 2.5V is CAN-L.
After understanding of the above, then you can use auto scanner to read DTC. Now make a brief introduction of operation steps for FCAR scanner to read DTC: Confirm diagnostic socket connect properly and then turn on power switch of scanner, and select Diagnostic menu (As shown in Pic.4-39).
11、Select vehicle type to be diagnosed：
Select vehicle type and then enter into vehicle series or engine select menu (as shown in 4‐40):Then enter into engine type or electronically controlled system menu (As show in Pic. 4‐41)
After entry to engine type or electronically controlled system menu, it will shows function menu of scanner (As show in Pic. 4‐42)
Pic.4-40 model or engine menu Pic.4-41 ECU menu
If need to clear DTC saved in ECU memory, then must select “Clear DTC” menu option. At present, all Electronic Control Systems are required to use this method. Some first generation of Electronic Control System can clear saved DTCs by way of using scanner or dismantling ECU power fuse for 10s and then install. The shortcoming of this kind of system is all DTCs appeared and recorded in the process of driving will disappear once driver cleared DTCs, therefore maintenance technician and fleet maintenance manager would know nothing about the problem of engine and vehicles.
Note: Before clearing DTC, better write down DTCs, also can use printing function of Fcar scanner.
Pic.4‐42 Function select menu