If you own a 1968 Mustang, you know that it’s a classic car that has a lot of charm and appeal. However, like any older car, it can have its share of problems. One problem that many Mustang owners face is a malfunctioning rear window defrost system. If this is something that you’re dealing with, then you’re in luck! In this article, we’ll provide you with a wiring diagram for the rear window defrost system and answer some frequently asked questions about it.
What is the Rear Window Defrost System on a 1968 Mustang?
The rear window defrost system on a 1968 Mustang is designed to clear the rear window of any condensation, frost, or ice that may accumulate on it. The system uses a series of wires and relays to heat up the rear window and remove any moisture or ice from it.
If your rear window defrost system is not functioning properly, you may notice that your rear window is foggy or has a buildup of frost or ice on it. This can make it difficult to see out of the rear window, which can be a safety hazard while driving.
Wiring Diagram for the Rear Window Defrost System
To fix your rear window defrost system, you’ll need to refer to a wiring diagram. Below is a wiring diagram for the rear window defrost system on a 1968 Mustang:
| Wire Color | Function |
|---|---|
| Black | Ground |
| Red/Blue | Power from the ignition switch (only active when the ignition is on) |
| Light Green | Rear window defrost switch – power to relay |
| Dark Green/Yellow | Rear window defrost switch – power to rear window element |
| Orange | Rear window defrost relay control |
This wiring diagram shows the different wire colors and functions for the rear window defrost system. By referring to this diagram, you can identify which wires may be causing your rear window defrost system to malfunction.
Black Wire – Ground
The black wire in the rear window defrost system is the ground wire. It provides a secure ground connection for the system, which is essential for it to function properly. If this wire is not properly grounded, the rear window defrost system may not work.
If you’re having issues with your rear window defrost system, you’ll want to check the ground wire and make sure it’s properly connected. You can use a multimeter to check the continuity of the ground wire and make sure it’s properly grounded.
Red/Blue Wire – Power from the Ignition Switch
The red/blue wire in the rear window defrost system provides power to the system from the ignition switch. This wire is only active when the ignition is on, which helps to conserve battery power when the car is not running.
If you’re not getting power to your rear window defrost system, you’ll want to check the red/blue wire and make sure it’s properly connected and receiving power from the ignition switch.
Light Green Wire – Rear Window Defrost Switch – Power to Relay
The light green wire in the rear window defrost system is connected to the rear window defrost switch and provides power to the relay. The switch is located on the dashboard and is used to turn on the rear window defrost system.
If you’re having issues with your rear window defrost system, you’ll want to check the light green wire and make sure it’s properly connected to the switch and the relay.
Dark Green/Yellow Wire – Rear Window Defrost Switch – Power to Rear Window Element
The dark green/yellow wire in the rear window defrost system is also connected to the rear window defrost switch. This wire provides power to the rear window element, which is responsible for heating up the rear window and removing any moisture or ice from it.
If you’re having issues with your rear window defrost system, you’ll want to check the dark green/yellow wire and make sure it’s properly connected to the switch and the rear window element.
Orange Wire – Rear Window Defrost Relay Control
The orange wire in the rear window defrost system controls the rear window defrost relay. This wire is used to turn on and off the relay, which is responsible for sending power to the rear window element.
If you’re having issues with your rear window defrost system, you’ll want to check the orange wire and make sure it’s properly connected to the relay and receiving power.
FAQs About the Rear Window Defrost System on a 1968 Mustang
How do I know if my rear window defrost system is not working?
If your rear window defrost system is not working, you may notice that your rear window is foggy, has a buildup of frost or ice on it, or is not heating up when you turn on the defrost switch. You may also notice that the defrost switch itself is not functioning properly.
How do I fix my rear window defrost system?
To fix your rear window defrost system, you’ll need to identify which wires or components are causing the issue. You can refer to the wiring diagram above to help you troubleshoot the system.
Once you’ve identified the issue, you can replace any faulty wires or components and test the system to make sure it’s working properly.
Can I install a rear window defrost system on my 1968 Mustang if it doesn’t have one?
Yes, you can install a rear window defrost system on your 1968 Mustang if it doesn’t have one. You’ll need to purchase a defrost switch, relay, and rear window element, as well as any necessary wiring and connectors.
It’s important to note that installing a rear window defrost system requires some electrical knowledge and experience. If you’re not familiar with automotive electrical systems, it’s best to have a professional install the system for you.
Is it safe to use my rear window defrost system?
Yes, it’s safe to use your rear window defrost system. However, it’s important to remember that the rear window element can get very hot, so you should avoid touching it while it’s in use.
You should also make sure that your rear window is free of any obstructions before using the defrost system. This will ensure that the system is effective and won’t cause any damage to your rear window or the defrost element.
