OBD-II Connector Pinout
Complete reference for the SAE J1962 16-pin OBD-II diagnostic connector. Mandatory in all road-registered vehicles sold in the US since 1996 and in the EU since 2001 (gasoline) / 2003 (diesel). Pin assignment is fixed; protocol on each pin depends on the manufacturer.
The 16-pin layout
Viewed looking into the female connector on the vehicle side (the side you plug your scanner into). Pin 1 is top-left.
Pin-by-pin reference
| Pin | Function | Notes |
|---|---|---|
| 1 | Manufacturer discretion | Often used for proprietary diagnostics (e.g. GM analog inputs). |
| 2 | SAE J1850 Bus+ (VPW or PWM) | Used on legacy GM (VPW) and Ford (PWM) vehicles. Phased out by ~2007. |
| 3 | Manufacturer discretion | Some Ford models use this for SCP (Standard Corporate Protocol). |
| 4 | Chassis Ground | Connected to the vehicle chassis. |
| 5 | Signal Ground | Reference for signaling, isolated from chassis ground. |
| 6 | CAN High (ISO 15765-4) | Mandatory CAN bus, 500 kbps for OBD-II. Most modern vehicles. |
| 7 | K-Line (ISO 9141-2 / ISO 14230) | Used by European/Asian manufacturers pre-CAN era. Half-duplex serial. |
| 8 | Manufacturer discretion | Some VAG vehicles use this for proprietary KW1281. |
| 9 | Manufacturer discretion | Rarely used. Some Japanese OEMs. |
| 10 | SAE J1850 Bus− (PWM only) | Used only with Ford PWM. Empty on GM VPW. |
| 11 | Manufacturer discretion | Various OEM-specific uses. |
| 12 | Manufacturer discretion | Some Honda models for K-Line variants. |
| 13 | Manufacturer discretion | Various. |
| 14 | CAN Low (ISO 15765-4) | Paired with pin 6 for CAN bus. |
| 15 | L-Line (ISO 9141-2) | K-Line companion; used for wake-up signal on some vehicles. |
| 16 | Battery +12V (unswitched) | Always live, even with ignition off. ~20 mA load typical scanners. |
Protocols and pin usage
ISO 15765-4 (CAN)
The standard OBD-II protocol on every vehicle since 2008 (US) / 2003 (EU CAN-mandated). Runs at 500 kbps.
Pins used: 6 (CAN-H), 14 (CAN-L), 16 (+12V), 4 or 5 (GND)
ISO 9141-2 / ISO 14230 (KWP2000)
K-Line protocol used on European and Asian vehicles, late 1990s through mid-2000s. Half-duplex single-wire serial.
Pins used: 7 (K-Line), 15 (L-Line, optional), 16 (+12V), 4 (GND)
SAE J1850 VPW
Variable Pulse Width — used on most GM vehicles 1995–2007. Single-wire 10.4 kbps.
Pins used: 2 (Bus+), 4 (CGND), 5 (SGND), 16 (+12V)
SAE J1850 PWM
Pulse Width Modulation — used on Ford vehicles 1996–2007. Two-wire 41.6 kbps.
Pins used: 2 (Bus+), 10 (Bus−), 4 (CGND), 5 (SGND), 16 (+12V)
SAE J2284 / CAN-FD
Newer extension to CAN, up to 5 Mbps. Used on premium vehicles 2018+ for higher-bandwidth diagnostics.
Pins used: same as standard CAN (6, 14) — protocol negotiated.
DoIP (ISO 13400)
Diagnostics over IP — fully Ethernet-based diagnostics. Used on Mercedes / BMW newer models alongside CAN for high-bandwidth ECU access.
Pins used: 3, 11 (Ethernet pairs) on some implementations. Often via separate connector.
Common gotchas
A few things that catch out new techs:
- Pin 16 is always live. Don't short it to ground. A blown OBD-II fuse leaves you with no scanner power and is annoying to find (usually in the interior fuse box, labeled "DLC" or "OBD").
- CAN termination is in the ECU, not the connector. If you tap into a CAN bus at the OBD connector you'll see proper termination resistance (60Ω across pins 6 and 14) only when the network is intact.
- K-Line idles HIGH. If you scope pin 7 and see ~12V resting, that's correct. The protocol pulls it low to send.
- Manufacturer pins vary widely. Don't assume — check the OEM service manual for non-standard pin assignments before probing.