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4th Gen Chassis Codes: EF | Model Years: 1988, 1989, 1990, and 1991
This page provides the complete 1988–1991 Honda Civic radio wiring diagram for the 4th generation Civic (chassis code EF). Use this guide when installing an aftermarket head unit or troubleshooting factory stereo issues in a 1988, 1989, 1990, or 1991 Honda Civic.
The 4th generation EF Civic is one of the most popular Honda platforms for modification and audio upgrades. Available as a hatchback, sedan, and wagon — and sharing its platform with the CRX — it used a standardized Honda radio harness. Front door speaker locations were common on Si and higher trims, while base models used dashboard-mounted speakers.
🔗 In This Guide
1988–1991 Honda Civic Stereo Wiring Diagram
Use the wiring table below for your 1988, 1989, 1990, and 1991 Honda Civic stereo wire color codes, speaker wiring, and harness pinout.
| Wire Function | Wire Color & Location |
|---|---|
| Battery Constant Power Wire (12V+) | White/Blue |
| Accessory Switched Power Wire (12V+) | Yellow/Red |
| Ground Wire | Black |
| Illumination Wire | Red/Black |
| Dimmer Wire | N/A |
| Antenna Trigger Wire | N/A |
| Amplifier Trigger Wire | N/A |
| Factory Amplifier Location | N/A |
| Rear View Camera Video Positive (+) | N/A |
| Rear View Camera Video Negative (–) | N/A |
| Dash Center Speaker Positive Wire (+) | N/A |
| Dash Center Speaker Negative Wire (–) | N/A |
| Front Left Tweeter Positive (+) | N/A |
| Front Left Tweeter Negative (–) | N/A |
| Front Right Tweeter Positive (+) | N/A |
| Front Right Tweeter Negative (–) | N/A |
| Front Left Speaker Positive (+) | Blue/Green |
| Front Left Speaker Negative (–) | Gray/Black |
| Front Right Speaker Positive (+) | Red/Green |
| Front Right Speaker Negative (–) | Brown/Black |
| Rear Left Tweeter Positive (+) | N/A |
| Rear Left Tweeter Negative (–) | N/A |
| Rear Right Tweeter Positive (+) | N/A |
| Rear Right Tweeter Negative (–) | N/A |
| Rear Left Speaker Positive (+) | Blue/Yellow |
| Rear Left Speaker Negative (–) | Gray/White |
| Rear Right Speaker Positive (+) | Red/Yellow |
| Rear Right Speaker Negative (–) | Brown/White |
| Subwoofer Positive Wire (+) | N/A |
| Subwoofer Negative Wire (–) | N/A |
1988–1991 Honda Civic Speaker Sizes and Locations
Use the speaker table below for your 1988, 1989, 1990, and 1991 Honda Civic speaker sizes and locations.
| Speakers | Speaker Size & Location |
|---|---|
| Front Tweeter Speaker Size | N/A |
| Front Tweeter Speaker Location | N/A |
| Front Speaker Size | 6 1/2″ Speakers |
| Front Speaker Location | Front Doors |
| Rear Tweeter Speaker Size | N/A |
| Rear Tweeter Speaker Location | N/A |
| Rear Speaker Size | 6 1/2″ Speakers |
| Rear Speaker Location (Coupe) | Rear Panels |
| Rear Speaker Location (Sedan) | Rear Deck |
| Subwoofer Speaker Size | N/A |
| Subwoofer Speaker Location | N/A |
Frequently Asked Questions
What harness adapter fits a 1988–1991 Honda Civic EF?
The EF Civic uses a Honda 10-pin and 6-pin radio connector. Metra 70-1721 is the most common adapter for this application and fits the vast majority of 1988–1991 EF Civic models. This adapter allows you to connect an aftermarket head unit to the factory wiring without cutting any factory connectors, which is important for maintaining wiring integrity on a vehicle this age.
What size speakers fit in the front doors of a 1988–1991 Honda Civic?
The EF Civic uses 6 1/2″ Speakers in the front door panels on Si and DX trims with door speakers. The factory mounting depth is shallow, so select aftermarket speakers with a mounting depth under 2.5 inches to avoid clearance issues with the door panel inner structure. A speaker adapter plate may also be needed depending on the aftermarket brand.
Does the 1988–1991 Honda Civic Si have a premium audio system?
No. The EF Civic Si did not include a factory premium audio system or Amplifier on any trim. However, the Si was popular as a base for aftermarket audio builds, and many EF Civics in the used market have had significant audio modifications. If purchasing an EF Civic with existing aftermarket audio, identify all installed components before planning your own upgrade.
How do I install a double-DIN radio in a 1988–1991 Honda Civic?
The EF Civic has a single-DIN factory radio opening and does not natively accept a double-DIN unit without dashboard modification. A custom Double-DIN Dash Kit or dashboard modification is required. Some owners fabricate a custom center console section to house a double-DIN unit, while others opt to keep a single-DIN head unit to maintain the original dashboard appearance.
What is the factory rear speaker size in a 1988–1991 Honda Civic hatchback?
The EF hatchback typically has a rear hatch area speaker configuration rather than a traditional rear deck. Speaker sizes in the rear vary by trim and body style — hatchback models often used 6″ x 9″ Speakers or 6 1/2″ Speakers in a parcel shelf location behind the rear seats. Confirm the exact cutout size in your specific body style before ordering replacement speakers.
Add Wiring Information
If you have verified 1988–1991 Honda Civic radio wiring data — wire colors, pin locations, harness adapter tips, or speaker sizes — please share it in the comments below. Community-submitted data is reviewed and added to the table above to help other 4th generation Civic owners. If you have a question about your 4th gen Honda Civic stereo installation, post it below and our community will work to find an answer.