Project-2: Back Door Wiring Harness Design

OBJECTIVE: To efficiently route the wiring harness for the car's back door body, adhering to industry packaging rules and best practices. This includes utilizing available connector 3D data sourced from www.te.com or other relevant sources and applying necessary protection coverings as per requirements. The project output comprises generating flattened wiring harness drawings and comprehensive reports of clearance analysis, clamping selections, harness fixing requirements and bundle continuity checks. The project aims to deliver a wiring harness system to the car's back door body that meets all functional requirements and quality standards.

GIVEN DATA: 
Back Door Surface Part:

   

MAIN PROJECT:

Introduction:
The wiring harness plays a critical role in an automobile's intricate network of electrical systems, enabling a seamless integration of various components to ensure proper functionality. In the context of the back door automotive wiring harness, plenty of essential electrical components are housed. From tail and brake lights to rearview cameras and defoggers, these components are essential to improve road safety, visibility, and communication. They are seamlessly integrated into the vehicle's main wiring harness through a diverse array of connectors, ensuring efficient and reliable electrical connectivity all over the vehicle. This project focuses meticulously on designing, implementing, and optimizing the wiring harness for the car's back door to deliver a harness that seamlessly integrates with the vehicle's overall electrical system, ensuring optimal performance and safety in every journey.

Effective Tips for Achieving Optimal Wiring Harness Routing:

1) Plan Ahead: Before beginning the routing process, carefully plan the path of wires that will follow. Consider factors such as component placement, accessibility, and potential sources of interference.
2) Follow Design Guidelines: Adhere to the design guidelines and specifications provided by the manufacturer or industry standards. These guidelines may include recommendations for wire spacing, bend radius, and clearance requirements.
3) Minimize Crossings: Minimize the number of wire crossings to reduce the risk of chafing, abrasion, and electromagnetic interference (EMI). Cross wires at right angles whenever possible to minimize contact and interference.
4) Avoid Sharp Edges and Obstacles: Route wires away from sharp edges, corners, and moving parts that could cause abrasion or damage. Use grommets, protective sleeves, or conduits to shield wires from potential hazards.
5) Secure Wires Properly: Use clips, clamps, zip ties, or adhesive mounts to secure wires along their path. Ensure that wires are adequately supported and do not hang or sag excessively, which could lead to strain and potential failure.
6) Maintain Separation: Keep high-voltage and low-voltage wires separate to prevent interference and minimize the risk of electrical faults. Use barriers or insulating materials to maintain separation between different types of wires.
7) Create Service Loops: Incorporate service loops or extra slack in the wiring harness at strategic points to allow for future adjustments, repairs, or component replacements without tension or strain on the wires.
8) Consider Environmental Factors: Consider environmental factors such as temperature variations, moisture, and chemical exposure when routing wires. Choose materials and routing methods that provide adequate protection against these conditions.
9) Label and Identify Wires: Label the wires regularly with identification markers or colour-coding to facilitate troubleshooting, maintenance, and repairs. Ensure that labels are visible and durable.
10) Test Routings: Before finalizing the routing of wires, conduct tests to verify that the proposed paths do not interfere with other components or systems. Make adjustments as necessary to optimize the routing for efficiency and reliability.

By following these tips, you can ensure proper wire routing, minimizing the risk of damage, interference, and electrical faults while maximizing the reliability and performance of the wiring harness.

List of electrical components that are housed on the back door:
Before routing the bundle, let us know the list of electrical components that are housed on the back door. This helps us to plan the types and number of connectors, as well as the respective mounting clips for connectors and clips for clamping the wire bundle.

1) Tail Lights: These are red lights placed at the vehicle's rear. They illuminate when the headlights are turned on, making the vehicle visible from the rear during low-light conditions.
2) Brake Lights: Brake lights are brighter red lights positioned near the tail lights, that activate when the driver applies the brakes. They signal to other drivers that the vehicle is slowing down or coming to a stop.
3) Turn Signal Lights: These lights, usually amber or yellow, indicate the driver's intention to turn left or right. They flash in the direction the driver intends to move.
4) Reverse Lights: The white lights at the back of the vehicle illuminate when the driver shifts into reverse. They alert other drivers and pedestrians that the vehicle is moving backwards.
5) License Plate Lights: The small lights illuminate the license plate, ensuring it is visible at night. This is a legal requirement in many regions.
6) High-Mounted Stop Lamp: Commonly known as the third brake light, this additional brake light is mounted higher than the standard brake lights. It enhances visibility, especially in situations when the vehicle in front may hide the view of the lower brake lights.
7) Reflector Units: While not lights, reflectors are often integrated into the rear section. They enhance visibility in low-light conditions by reflecting the headlights of other vehicles.
8) Rear Window Defogger: A grid of heating elements embedded in the rear window to remove condensation and frost for improved visibility.
9) Rear Window Wiper: A windshield wiper mounted on the rear window to remove rain, snow, or debris for better rearward visibility in adverse weather conditions.

The specific design and arrangement of these lights may vary between various car models and manufacturers, but these components are generally standard in most modern vehicles for safety and regulatory compliance.

Wiring Harness Routing Design for Back Door:

STEP-1:- Establishing the Electrical Definition of Components
The CAD data for the connectors and the necessary mounting components for routing the wiring harness of the back door were downloaded. Subsequently, all geometry features and electrical properties were defined.

1) C-776438-4 (Inter-Connection Connector):

2) C-1924487-2 (ICC Cavity Clip):

3) C-1563689-1:

4) C-DT06-08SA:

5) C-282080-1:

6) C-173090-2:

7) C-DT06-6S:

8) 2 Pole Connector:

9) Fir Tree Clip (Ø 15mm)

10) Fir Tree Clip (Ø 12mm)

 STEP-2:- Product Creation
A new CAT product called "Back Door Harness Context Assembly" was created, and the given Back Door Assembly was imported. Then, a new product named "Back Door Harness GB Assembly" was created under the same product to position the connectors and route the geometrical bundle to them.

 STEP-3:- Importing Connectors into the Assembly
The electrically defined connectors were imported one by one under the "Back Door Harness GB Assembly" product and positioned at respective locations on the back door by using various positioning commands like snap,  smart move, manipulation, etc., available in the assembly workbench for easy wire harness routing.

a) Inter-Connection Connector (C-776438-4):- Interconnection connectors are used in wiring harness design to facilitate connection between different segments or sections, making assembly, disassembly, and maintenance more efficient. It was positioned at the centre top of the back door.  

b) C-1563689-1:- This connector was utilized for the backlight console, which comprised a tail light, brake light, reverse light, and turn signals, and it was positioned at two points near the light console mounting area for the ease of wire routing.

c) C-DT06-08SA:- This connector was utilized for the rear side wiper motor connection and it was positioned near the wiper motor mounting area for easy wire routing.

d) C-282080-1:- This connector was utilized for the license plate spotlight connection and was positioned near the license plate area for easy wire routing.

   

e) C-173090-2:- This connector was utilized for the rearview camera connection and it was positioned near the rearview camera for easy wire routing.

f) C-DT06-6S:- This connector was utilized for the defogger connection and was positioned near the license plate area for easy wire routing.

   

g) 2 Pole Connector:- This connector was utilized for the high-mounted stop lamp connection and was positioned near that area for easy wire routing.

   

 STEP-4: Positioning of Fir Tree Clips
1) The bundle diameter, branch points, and wire routing were planned once the connectors had been positioned at the ideal locations. 
2) Following that, the positioning of the fir tree clips was temporarily locked.
3) According to the design rules, a minimum gap of 50 mm was maintained between the fir tree clips to avoid to many fir tree clips, and a maximum distance of 200 mm was not exceeded to prevent sagging between two fir tree clips.
4) If any additional fir tree clips were required for proper bundle routing and bundle safety, that was also communicated to the BIW Team.
5) After concealing and obtaining approval from the BIW Team, the fir tree clip positions were finalized and the fixation holes were created on the back door assembly by the BIW Team.

STEP-5:- Bundle Routing
1) To route the wire bundle, we switched to the Electrical Harness Assembly Workbench and defined the "Back Door Harness GB Assembly" electrically by using the command Geometrical Bundle available in the Electrical Harness Assembly Workbench.
2) Then for creating the branches, the Multi-Branchable Document command was selected and the bundle segments were created one by one.
3) Each branch segment was created by selecting the components individually as per the bundle routing plan. For example, the Inter-Connection connector was selected initially and then the fir tree clip was selected to route the wire bundle.
4) The main branch started from the Inter-Connection connector and ended at the defogger (C-DT06-6S) connector.
5) The bundle diameter for the main branch was given 10mm and the minimum bend radius ratio was set to 1.4. 

6) The branch points were created at appropriate distances to create and route the harness branch to the connectors individually from the main branch.
7) The bundle diameter for the harness branch was given 8 mm for the tail light and wiper motor connectors. Then, the minimum bend radius ratio was set to 1.4.
8) The bundle diameter for the harness branch was given 6 mm for the license plate light, rearview camera, and high-mounted stop light connectors. Then, the minimum bend radius ratio was set to 1.4.
9) A certain percentage of slack was provided for some bundle segments for proper routing and easy serviceability.

STEP-6: Bundle Continuity Check 
Bundle continuity in a wiring harness assembly is to check a seamless and unbroken electrical connection throughout the entire layout of the bundled wires. It helps to ensure that there are no interruptions or discontinuities in the electrical lines within the harness. Checking bundle continuity involves verifying that all wires within the harness are properly connected, with no breaks or disruptions, contributing to the overall functionality and reliability of the electrical system. 

The bundle connectivity was checked for the wiring harness and there were no breaks or discontinuities on it.

STEP-7:- Applying Protective Covering
Corrugated tubes were provided for all the bundle segments based on the bundle diameter as a protective covering with an end extremity at 30mm from the connector's end.

 

STEP-8:- Wiring Harness Flattening

1) A new product file was created and switched to the Electrical Harness Flattening Workbench. Then, I saved the file as Back Door Harness Flattening in the same location where all the files were stored.
2) The 'Harness Flattening Parameters' settings were defined to flatten the wiring harness assembly. 
3) The 'Extract' option was selected in the Electrical Harness Flattening Workbench, and the "Back Door Harness GB Assembly" Product was selected in the "Back Door Harness Context Assembly" product file. Subsequently, the Geometric Bundle assembly was imported into the Wire Harness Flattening product file with an 'EHF' extension.

4) Select the Flatten option, provide the active plane and define the algorithm and angle mode. Then choose the branches which are to be flattened and hit the ok button.

 STEP-5: Use 'Rotate' and other commands to align the branches and properly orient them as per the given layout.

STEP-9: Drawing View

1) A new drawing file was created and ensured to be saved in the same designated location. The title block template was inserted into the drawing sheet, and the necessary details were entered within the title block.
2) The front view of the harness assembly was inserted by selecting any flat face of the connector. The orientation of the wire harness was adjusted for better viewing.
3) The properties were accessed, and the '3D Wireframe' and 'Is always visible' options were enabled to ensure a clear visualization of wire bundles, connectors, and protective coverings.

Conclusion:
Thus, the required connectors and mounting clips are electrically defined and routed the wire harness design successfully for the car's back door body by following the industry packaging rules and best practices. On top of that, the corrugated tubes were provided as a protective covering for the geometrical bundle and validated the bundle continuity checks, clamping selections and harness fixing requirements.