For automotive enthusiasts and DIY mechanics, customizing your vehicle’s electrical system can be a rewarding project. This guide will walk you through the process of building your own fuse block and integrating an OBD2 diagnostic port. Using readily available components, including the crucial 829-12110250 Obd2 port connector, you can create a robust and organized power distribution system for your car, truck, or custom project. This setup is versatile and applicable to various wiring harnesses, including LT1, LS1, and Vortec truck engines.
Parts You’ll Need: Fuse Block and OBD2 Port Essentials
Before starting, gather all the necessary parts. Having everything on hand will streamline the building process. Below is a comprehensive list of components for both the OBD2 diagnostic port and the fuse block and relay setup.
OBD2 Diagnostic Port Components
| Part Description | Vendor | Part Number | Quantity Needed |
|---|---|---|---|
| OBD2 Port Plastic Connector, 16 Pin | Mouser.com | 829-12110250 | 1 |
| Terminals – for OBD2 port | Mouser.com | 829-12129373 | 4 |
| Terminal Lock – secures terminals | Mouser.com | 829-12160437 | 2 |
| Check Engine Light (MIL) Lamp (Optional) | Allelectronics.com | Check lamps/indicators, inventory changes | 1 (Optional) |
The 829-12110250 OBD2 port connector from Mouser is the centerpiece for creating a functional diagnostic interface. Ensure you order the accompanying terminals and locks for secure and reliable connections.
Fuse Block and Relay Components
| Part Description | Vendor | Part Number | Quantity Needed |
|---|---|---|---|
| Fuse Block Housing kit (terminals incl.) | RockAuto.com / Terminalsupplyco.com | 85668 | 1 |
| Relay Socket | Allelectronics.com | SRLY-2 | 2 |
| Relay 30 Amp | Allelectronics.com | RLY-351 | 2 |
| Relay Terminal 14-18 AWG | Mouser.com | 571-42238-2 | 8 |
You may find the Dorman fuse block part #85668 at AutoZone or RockAuto.com. This kit typically includes the necessary terminals, simplifying your parts sourcing.
A collection of fuse block components, including the housing, terminals, and wiring, essential for building a custom automotive electrical system.
Fuse Block Wiring: Step-by-Step Assembly
Let’s delve into the fuse block wiring process. The relay sockets from Allelectronics often come with pre-installed short wires and terminals. It’s highly recommended to remove these and use new terminals, as the stock wiring may not be adequate for the current demands of your fuse block. The SRLY-2 relay sockets are specifically chosen because they conveniently slide onto the side of the fuse block housing.
Always order extra terminals for all components – OBD2 port, relay sockets, and fuse holder. These are inexpensive insurance against mistakes or changes during assembly. For robust and reliable connections, crimp and solder all terminals.
Close-up view of terminals and fuse block sections, showcasing the components ready for assembly and wiring in a custom automotive electrical project.
Step 1: Preparing the Fuse Terminals
The fuse block kit often includes bussed terminals. Separate a set of four bussed terminals into a group of three and a single terminal. This configuration will allow for both common and independent fused circuits.
Step 2: Connecting the Relay Output
Using terminals suitable for heavier gauge wire, crimp and solder them onto the relay OUTPUT leg as shown in the following image.
Detailed image showing the connection of a relay output terminal to a set of bussed fuse terminals within the fuse block assembly process.
Step 3: Installing Terminals into the Fuse Block
Install the prepared relay OUTPUT terminal and the three bussed fuse terminals into the fuse block housing. Push them in until they click securely into place.
Image demonstrating the relay and fuse terminals properly inserted and secured within the fuse block housing, ensuring a stable electrical connection.
Step 4: Connecting Power Input
Next, install the relay INPUT terminal. The red wire connected to this terminal will be your 12V+ battery hot feed. This wire will also supply constant power to the designated fuse on the end of the block, providing always-on power for specific circuits.
Step 5: Wiring Relays for Fuel Pump and Keyed Power
- For the fuel pump relay, connect a gray 16 AWG wire to a terminal and install it into the OUTPUT leg of the relay socket.
- For the second relay, connect a PINK wire to a terminal and install it into the relay coil location. This PINK wire will be your KEY HOT power source, which activates the relay and powers up the three bussed fuses when the ignition is turned on.
A mid-assembly view of the fuse block wiring, highlighting the progressive connections of relay and fuse terminals for a functional automotive circuit.
Step 6: Distributing Keyed Hot Fuses
With the remaining fuse and relay terminals, begin grouping your PINK (keyed hot) wires for the three key hot fuses. Carefully plan your circuits and document your layout for future reference. Consider including a dedicated fuse for the check engine light (MIL) circuit.
Step 7: Constant Power and Fuel Pump Relay Input
Connect the ORANGE wire (battery constant power) to the PCM (Powertrain Control Module) and create a jumper wire to the fuel pump relay INPUT terminal. This ensures constant power to the PCM and provides the necessary input for the fuel pump relay.
Image focusing on the addition of constant power and fuel pump relay input wires to the fuse block, crucial for PCM operation and fuel delivery system control.
Step 8: Grounding Relay Coils and Fuel Pump Relay Control
Install the GROUND wire for each relay coil, using a jumper from the first relay to the second for convenience. The PCM will supply a 12V+ signal to trigger the fuel pump relay. Connect the Fuel Pump Relay control wire from the PCM to the appropriate relay coil terminal.
Step 9: Preparing Wires for OBD2 Port and Check Engine Light
Prepare the coiled wires – pink, orange, and black – for the diagnostic port and check engine light. Making these wires approximately 6 feet long provides ample length to reach inside the vehicle’s cabin for convenient OBD2 port access and check engine light visibility.
Parts for the OBD2 port assembly are displayed, including the connector housing 829-12110250, terminals, and wires prepared for integration into the vehicle’s electrical system.
OBD2 Diagnostic Port Wiring
All OBD2 ports for LS1 and Vortec Truck applications share a common wiring configuration. Here’s the standard OBD2 port wiring guide:
- Pin 2: Serial Data – Connects to the PCM (data output).
- Pin 4 & 5: GROUND – Connect to chassis ground. Pin 5 is typically sufficient, but some scan tools may require ground on Pin 4 as well.
- Pin 16: 12V+ BATTERY – Connect to a constant 12V+ battery source.
OBD2 LT1 (96-97 ONLY) Wiring Additions:
For 1996-1997 LT1 vehicles, additional wiring to the OBD2 port is required:
- Pin 6: Diagnostic Request/Field Output Enable
- Pin 9: UART Serial Data
Note that 1995 LT1 vehicles used an OBD2 port connector but were not fully OBD2 compliant. These earlier systems used Pin 9 for serial data instead of Pin 2.
By following these steps, you can successfully build a custom fuse block and integrate an OBD2 diagnostic port using the 829-12110250 OBD2 connector, enhancing your vehicle’s electrical system and diagnostic capabilities. Remember to always double-check your wiring and connections for safety and optimal performance.
