How to Replace the Wiring Harness in a 1991 Ford Festiva

Introduction

Replacing the wiring harness in your 1991 Ford Festiva can be an intimidating task, but with the right tools and knowledge, it is very doable for the home mechanic. In this comprehensive guide, I will walk you through the complete process of removing the old wiring harness and installing a new one.

Reasons for Replacement

There are several reasons why you may need to replace the wiring harness in your Festiva:

• Electrical issues: If you are experiencing strange electrical gremlins like lights flickering, radio cutting out, or gauges acting erratically, there may be broken wires or loose connections in the harness. Replacing it can resolve these problems.

• Accident damage: If your Festiva has been in an accident, the wiring harness may have been damaged. Replacing it ensures all the wires are in good condition.

• Preventative maintenance: The wiring harness deteriorates over time. Replacing it ahead of any issues ensures the electrical system functions properly.

Preparation

Replacing the wiring harness is an extensive job, so make sure you have all the necessary tools, parts, and time set aside before getting started:

• New wiring harness: Purchase a complete new harness specifically for a 1991 Festiva. Do not try to splice in a universal harness.

• Basic hand tools: You will need wrenches, screwdrivers, pliers, wire cutters/strippers.

• Electrical tape and wire connectors: For splicing wires together.

• Zip ties: To secure the new harness in place.

• 4-6 hours: Plan to spend a full afternoon on this job. Rushing increases the chance of mistakes.

Removing the Old Harness

With your tools gathered, now we can get started:

1. Disconnect the Battery

Always disconnect the negative terminal on the battery before working on the electrical system. This prevents short circuits or shocks.

2. Remove Interior Trim

• Remove the sill plates, kick panels, and middle console. This allows access to wiring behind the panels.

• Unbolt the dashboard and pull it back. But do not disconnect the harness yet.

3. Detach Accessory Connections

• Unplug headlights, taillights, computer sensors - anything connected to the old harness. Label wires as you go.

• Cut any zip ties bundling wires together. The harness needs to be totally free.

4. Remove the Main Harness

• With all connections detached, you can now work the harness free from the car. Pull it through grommets or cut them away if needed.

• Unbolt the harness from any mounting brackets.

• The old harness is now fully removed!

Installing the New Harness

Installation is essentially the reverse of removal:

1. Feed the New Harness In

• Start by feeding the new harness through the same path as the old one.

• Pull it through grommets and clip it back into mounting brackets.

2. Reconnect Accessories

• Refer to your labels and plug all accessories back into the matching connectors on the new harness.

• Use zip ties to bundle loose wires back together.

3. Secure the Harness

• Make sure the harness is routed properly and away from hot or moving parts.

• Use zip ties and mounting clips to secure it in place.

4. Reinstall Trim and Battery

• Bolt the dashboard back in place and reinstall kick panels and other trim.

• Reconnect the battery when everything is back together.

Starting the Car

With the new harness fully installed:

• Turn the key to accessories mode and check gauge operation.

• Start the car and verify all lights and accessories function properly.

• Let the car run and watch for any shorts or issues with the new harness.

• If it checks out, you're good to go!

Conclusion

While replacing the wiring harness is labor intensive, it can restore your Festiva's electrical system and fix issues caused by damaged wires. Just take your time, label everything, and use the proper tools. Follow these steps and you can successfully complete this repair yourself and get your Festiva back on the road!