OBD-2 universal for PWM, VPW, and ISO 9141-2 vehicles

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connector or cable wiring scheme

16 pin car OBD2 special connector layout 16 pin car OBD2 special connector at the car

This device is a CMOS microcontroller which is designed to interface a personal computer or laptop with a vehicle’s On Board Diagnostic (OBD II) interface. It is intended to function with all three of the protocols used by vehicle manufacturers to implement the OBD II system as defined by SAE and ISO specifications. The OBD II system became mandatory for 1996 and up vehicles, but some vehicles were already fully or partially compatible with OBD II requirements prior to 1996. The chip is not suitable for the earlier vehicles such as OBD I. The device is intended to function as a simple scan tool and is capable of sending and receiving any OBD II message defined in SAE J1979 for any of the three types of OBDII bus implementations (PWM, VPW, ISO 9141-2). It can also be used as an inexpensive interface for custom instrumentation monitoring various vehicle parameters such as speed, RPM, coolant or intake air temperature, engine load, intake air flow rate, etc.

OBD 2 universal cable


C5, C6  .01 UF, 25V 
C4      .1 UF, 25V  
C3      .47 UF, 50V  
C2,C1    20 pf, 50V  
R11, R12, R23, R9, R1, R3, R4, R25, R8  10 KOhm, 1/4 Watt  
R24 18 KOhm, 1/4 W  
R19, R18, R7, R20, R22, R5, R6, R13 1 KOhm, 1/4 W  
R21 5.6 KOhm, 1/4 W 
R16, R17 510 Ohm, 1/4 W 
R10 62 KOhm, 1/4 W 
R15 9.1 KOhm, 1/4 W 
R14 270 Ohm, 1/2 W 
R2   - Not used   
D2  1N4739 Zener, 9.1V, 1W  
D1, D3  1N4148 Diode 
Q3, Q4, Q5 PN2222 Transistor, NPN 
Q2 PN3904 Transistor, NPN 
Q1 PN3906 Transistor, PNP 
IC2 7805 Regulator, 5V 
IC3 LM339N Quad Comparator  
IC1 16F84-20 Microprocessor (firmware 1.07) 
XTL 1 20 MHz Crystal, 20 Mhz 

If you don’t use PWM, you can omit R4, R6, R7, R8, R9, R10, Q1, Q2, D1. If you don’t use ISO, you can omit R15, R16, R17, R18, R19, R21, Q4, Q5 If you don’t use VPW, you can omit R13, R14, R23, R24, D2, D3, Q3Don’t connect external power sources - all power direved from pin 16 of OBDIISerial port works at 19200 baud



Category:Car Connectors


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