How to Replace the Wiring in Your 20 Year Old Minivan

Introduction

Replacing the wiring in an older vehicle like a 20 year old minivan can be a daunting task, but with some preparation and patience, it is doable for a mechanically inclined DIYer. In this article, I will walk through the complete process of replacing the wiring step-by-step.

Reasons to Replace Minivan Wiring

There are a few common reasons you may need to replace the wiring in an aging minivan:

Electrical issues: As wiring ages, it can become brittle and corroded. This can lead to shorts, blown fuses, and electrical components failing. Replacing old wiring can resolve many gremlin electrical issues.
Adding new features: If you want to add new electronics like backup cameras, Bluetooth stereos, or other accessories, you may find the old wiring is not up to the task. New wiring makes adding electrical features easier.
Preventive maintenance: Replacing wiring before problems occur can avoid being stranded with electrical failures down the road. If your minivan is approaching 20 years old, its wiring is likely near the end of its lifespan.

Preparation

Replacing wiring is a time consuming project, so make sure to set aside a full weekend and prepare accordingly:

Get repair manuals - Obtain a service manual and wiring diagram for your specific minivan make and model. This is essential to understand routing and connector details.
Plan necessary tools - At minimum you'll need basic hand tools, a volt meter, wire crimpers, electrical tape, and wire strippers.
Have replacement wiring - Purchase new wiring harnesses designed for your minivan. Complete full harness kits are available online.
Remove accessories - Take out seats, panels, carpeting and anything else that needs to be removed to access all wiring.

Removing Old Wiring

With preparation done, it's time to remove the old wiring:

Disconnect the battery - Always disconnect the battery before working on vehicle wiring.
Remove interior panels - Take out all interior trim pieces that provide access to wiring. Label wires as you remove.
Unplug connectors - Unplug all electrical connectors in the engine bay, interior and rear of the vehicle.
Cut zip ties - Clip any zip ties bundling wires together so wiring can be fully extracted.
Pull wiring - Carefully pull wiring through conduits, grommets and holes as you extract it from the vehicle.
Coil and label - As each wiring section is removed, coil it neatly and label both ends clearly for installation.

Installing New Wiring

Here are the steps to install fresh wiring throughout the minivan:

Run new wires - Starting at one end, carefully thread each new wire through all the same passages as the old wiring.
Connect terminals - Following your diagram, splice and crimp the new wires into labeled connectors. Soldering is recommended for solid connections.
Secure wires - Bundle wires together and secure with new zip ties just like the original harness. Don't over tighten ties.
Test connections - Use your voltmeter to test and verify connectivity of all wires before connecting the battery.
Plug in connectors - With wiring fully secured and tested, plug all electrical connectors back into their respective components.
Reinstall panels - Carefully reinstall all interior panels that were removed to access wiring.
Reconnect battery - With everything reassembled, reconnect battery power. Turn ignition and test electrical systems before reassembling further.

Finishing Touches

With new wiring installed, there are a few final steps to button up the project:

Repeat steps - If any issues are found with electrical components during testing, trace wires back and repeating installation steps may be needed.
Install accessories - With a clean wiring setup, it is now easy to install any new accessories you may want.
Secure panels - Confirm all interior trim panels are securely reinstalled with fresh hardware if needed.
Confirm function - Verify full functionality of lights, engine systems, gauges, and anything else wired through the new harness.
Close up - Reinstall any remaining interior components like seats to complete the project.

Conclusion

While replacing wiring in an aging minivan is very labor intensive, the job can be completed by an experienced DIYer equipped with repair manuals, proper tools and new harness kits. Taking precautions like labeling wires and testing connections as you go makes the process less daunting. Investing a full weekend into this preventive maintenance project can restore solid electrical function and keep your minivan running smoothly for years to come.