OBD2 Splitter Switch: A DIY Solution for Multiple Devices

Connecting multiple devices to your car’s OBD2 port can be a challenge. A radar detector with a SAVVY module for auto-muting, a WiFi OBD2 reader for performance data logging with apps like TrackAddict, and a coding dongle like E-SYS all require access to this crucial port. Using an Obd2 Splitter Switch offers a clean and efficient solution for managing these competing demands. This article details a DIY approach to installing an OBD2 splitter switch, allowing seamless switching between different OBD2 devices.

Why Use an OBD2 Splitter Switch?

An OBD2 splitter, essentially a Y-cable with one male and two female connectors, allows connection of multiple devices. However, devices often compete for connection, leading to intermittent data flow. A simple splitter doesn’t prioritize which device gets access. This is where an OBD2 splitter switch comes in. By controlling power to pin 16 of the OBD2 connector, a switch enables the user to manually select which device receives power and connects to the vehicle’s computer. This eliminates the connection conflicts inherent in a basic splitter.

Building Your OBD2 Splitter Switch

This DIY project involves modifying a standard OBD2 splitter cable with a single-pole-double-throw (SPDT) switch.

Identifying Pin 16

1. Dissect the Splitter: Carefully cut open one side of the OBD2 splitter cable, exposing the internal wiring.

2. Locate Pin 16: Use a voltmeter to identify the wire connected to pin 16 on the male end of the splitter. A thin needle can help pierce the wires inside the cable. In this specific project, pin 16 was a green wire with a white stripe. The following wire color map was observed in the purchased splitter:

   • Red: 3
   • Black: 13
   • Grey: 9
   • Purple: 8
   • Red/Pink: 15
   • Orange: 4
   • White: 10
   • Pink: 11
   • Light Green: 12
   • Yellow: 5
   • Blue: 7
   • Green/White: 16

3. Verify and Cut: Confirm the identified wire is indeed pin 16 on both sides of the splitter. Cut both pin 16 wires and prepare them for soldering.

Wiring the Switch

1. Solder and Connect: Solder heavier gauge solid core wire to the cut ends of the green/white wires.
2. Attach to Switch: Connect these wires to the corresponding terminals on the SPDT switch.

Installing the Switch and Splitter

This project utilizes the small storage cubby to the left of the steering wheel for a concealed installation.

1. Prepare the Cubby: Remove the cubby and cut a hole large enough to pass the OBD2 connector through. A slot behind the hole accommodates the cable. Cover the hole with the cubby’s rubber mat for a clean finish.

2. Mount the Switch: Drill a hole for the SPDT switch inside the cubby and mount it securely.

3. Connect and Conceal: Route the splitter cable through the hole and connect the modified splitter to the switch. An OBD2 extension cable with a 90-degree angle can provide extra slack.

Final Result

The finished product offers a hidden, easily accessible solution for switching between OBD2 devices. A simple flick of the switch toggles between the connected devices, enabling seamless transitions between using a radar detector, data logging with a WiFi OBD2 reader, or using a coding dongle.