1. Example DB9 to OBD2 Pinout
The table below is an example only. DB9-to-OBD2 wiring is not standardized across all devices. Some devices use DB9 pins for RS232 TX/RX, while others reuse DB9 pins for CAN High, CAN Low, power, ignition, or custom signals.
For the complete pinout mapping table (including OBD2 16-pin reference), see OBD2 to DB9 Diagnostic Cable: Pinout Mapping.
DB9 9-Pin Reference
| Pin | Standard RS232 Signal | Example Use in OBD2 Cable |
|---|---|---|
| 1 | DCD | Not used |
| 2 | RXD | K-Line data (example) |
| 3 | TXD | L-Line data (example, optional) |
| 4 | DTR | Not used |
| 5 | GND | Ground reference |
| 6 | DSR | Not used |
| 7 | RTS | CAN High (example, non-RS232) |
| 8 | CTS | CAN Low (example, non-RS232) |
| 9 | RI | +12V power (example, non-RS232) |
2. DB9 Male vs Female
A common point of confusion is connector gender:
- OBD2 end: Usually an OBD2 male J1962 plug — it plugs into the vehicle's female OBD-II port.
- DB9 end: Often DB9 female socket, but this depends on the GPS tracker, scan tool, or telematics device. Some devices use DB9 male; others use DB9 female.
Always check the mating connector on your device before ordering or building a cable.
3. Wire Color Conventions
Wire colors are not standardized for OBD2-to-DB9 cables. They vary by cable manufacturer, device brand, and customer drawing. Never rely on wire color alone. Always verify pin-to-pin continuity before connecting the cable.
| Signal | Common Color (Aftermarket) | Alternative |
|---|---|---|
| K-Line (OBD2 Pin 7) | Blue | White, Yellow |
| L-Line (OBD2 Pin 15) | Green | Orange |
| Ground (OBD2 Pin 4/5) | Black | Brown |
| +12V (OBD2 Pin 16) | Red | Orange, Pink |
| CAN High (OBD2 Pin 6) | Yellow | White, Blue |
| CAN Low (OBD2 Pin 14) | Green/White | White/Black |
4. How to Verify Your Cable Wiring
- Set your multimeter to continuity (beep) mode
- Probe from DB9 Pin 2 to OBD2 Pin 7 → should beep (K-Line, if this pinout applies)
- Probe from DB9 Pin 5 to OBD2 Pin 4 → should beep (Ground)
- Probe from DB9 Pin 5 to OBD2 Pin 5 → may beep (both grounds often tied)
- Check that DB9 Pin 2 has NO continuity to DB9 Pin 5 (no short to ground)
- If CAN is wired: verify OBD2 Pin 6 and Pin 14 map to the expected DB9 pins per your device manual
- If +12V is wired: verify OBD2 Pin 16 maps to the expected DB9 pin
- Verify NO shorts between any two signal pins
5. Request Pinout PDF
If you need a printable pinout reference for your specific device or application, send us the device model or customer drawing. We can provide a pinout diagram matched to your actual wiring requirements.
Frequently Asked Questions
Q: What is the standard wire color for OBD2 K-Line?
A: There is no universal wire color standard for OBD2-to-DB9 cables. Wire colors vary by cable manufacturer, device brand, and customer drawing. Never rely on wire color alone. Always verify pin-to-pin continuity before connecting the cable.
Q: How do I identify DB9 male vs female?
A: DB9 Male has 9 protruding pins; DB9 Female has 9 sockets. The OBD2 end is usually a J1962 male plug that connects to the vehicle's female OBD-II port. The DB9 end is often a DB9 female socket, but this depends on the GPS tracker, scan tool, or telematics device.
Q: Can I use this cable with a USB-to-serial adapter?
A: Only if the connected diagnostic interface is designed for RS232 communication and the cable pinout matches that device. A generic USB-to-RS232 adapter cannot decode OBD-II, CAN, or K-Line data by itself. For direct vehicle diagnostics, use a proper OBD-II interface that supports the required protocol.
Q: How do I test if my cable is wired correctly?
A: Use a multimeter in continuity mode. Test each expected pin-to-pin connection. Verify there are no shorts between signal pins. If CAN is wired, verify OBD2 Pin 6 and Pin 14 map to the expected DB9 pins. Always follow the device manual or customer drawing for the correct pinout.
Q: Where can I find a DB9 to OBD2 wiring diagram?
A: This article provides an example DB9 to OBD-II pinout diagram for reference. However, there is no universal standard pinout. Always verify the wiring against your device manual, customer drawing, or sample cable before use.
Need This DB9 to OBD2 Pinout Made as a Cable?
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