Stereo – Head Unit and Speaker Replacement Guide – 2.5L NA

Overview

This guide covers the replacement of the stereo head unit and speakers in all Porsche 944 variants with an 8-valve engine configuration, for both pre-1985.5 (83-85.5) and 1985.5 onwards (86-88) models. Replacing the head unit and speakers enhances audio quality and allows for modern features like subwoofer outputs. The process involves installing a new DIN head unit and replacing the four 4×6 Euro-cut speakers, addressing fitment challenges, especially for front speakers due to door panel constraints. This guide ensures a seamless upgrade while maintaining factory aesthetics where possible.

Pink and blue text represent links to additional resources, tools, parts, and partner websites.

Tools Required

• Phillips screwdriver
• 10mm (3/8 inch) wrench
• Small hammer
• Wire cutters/strippers
• Electrical tape
• Multimeter (optional, for testing antenna amplifier power lead)

Parts Required

• DIN head unit with mounting frame (check for subwoofer out/rear speaker out if planning subwoofers)
• Four 4×6 Euro-cut or American-cut speakers (e.g., Alpine SXE-4625S for front/rear or Rockford Fosgate HPC1246 for rear)
• Antenna amplifier power lead (if not included with head unit)
• Blank switch cover (optional, for 1985.5 onwards models bypassing fader, 944 552 139 00)
• 1/4 inch (6mm) speaker spacers (for front speakers, reuse factory spacers if possible)
• Aftermarket 4×6 speaker grills (optional, e.g., American International 4×6 grills, AI 4×6 Grill)

Step-by-Step Procedure

Step 1: Prepare for Head Unit Replacement

1. Disconnect the negative battery terminal using a 10mm (3/8 inch) wrench to ensure safety during electrical work.
2. Remove the factory head unit by gently prying it out of the dashboard, using a Phillips screwdriver to remove any retaining screws if present.
3. Identify the antenna amplifier power lead: locate the black lead tied to the antenna or the two red wires with white stripes feeding into it. Use a multimeter to confirm which wire supplies power if needed.

Step 2: Install the New Head Unit

4. Attach the mounting frame (included with the new head unit) to the DIN head unit, following the manufacturer’s instructions.
5. Connect the head unit’s wiring harness to the vehicle’s wiring. Ensure the antenna amplifier power lead (black or red with white stripes) is connected to the head unit’s power output for the antenna amplifier.
6. (Pre-85.5) Connect the head unit’s left and right channel outputs directly to the vehicle’s speaker wires, as these models lack a factory fader.
7. (85.5 Onwards) If using a two-channel head unit, connect the left and right channel outputs to the fader input wires on the center console. If using a four-channel head unit, bypass the fader by connecting directly to the four speaker leads coming out of the fader for full head unit fader control.
8. (85.5 Onwards, Optional) If bypassing the fader, remove the fader switch from the center console using a Phillips screwdriver and install a blank switch cover (944 552 139 00).
9. Slide the head unit into the dashboard and secure it with the mounting frame’s screws or clips. Test the head unit to ensure it powers on and the antenna amplifier works (radio reception is clear).

Step 3: Remove Front Speakers

10. Remove the door panel by unscrewing the Phillips screws along the bottom and sides, then gently pry the panel off its clips.
11. Unscrew the factory 4×6 speaker from the door panel using a Phillips screwdriver, noting the 1/4 inch (6mm) spacer behind it. Retain the spacer for reuse.
12. Disconnect the speaker wires, labeling them if necessary to track polarity (positive/negative).

Step 4: Install New Front Speakers

13. Select 4×6 Euro-cut or American-cut speakers (e.g., Alpine SXE-4625S). If using American-cut speakers, loosen the bottom of the door panel to slide the mounting plate edges underneath or trim the plate with wire cutters for fitment.
14. Check speaker depth: ensure the speaker, including the magnet, is no deeper than 1-3/4 inches (44mm) with the factory 1/4 inch (6mm) spacer to avoid the door window channel. Use a thicker spacer if needed, but note that factory grills may not sit flush.
15. If the speaker frame is slightly larger than the door panel’s oval cutout, use a small hammer to gently tap and flatten the lip of the cutout for a flush fit.
16. Connect the new speaker wires, ensuring correct polarity, and secure the speaker to the door with the factory spacer and screws.
17. Test the speaker by powering on the head unit. If using factory grills, ensure they sit flush (no parts protrude more than 1/4 inch or 6mm above the speaker surface). If not, install aftermarket grills (AI 4×6 Grill) that protrude no more than 1/2 inch (13mm).
18. Reattach the door panel, ensuring it sits flush with the dash when the door is closed.

Step 5: Remove Rear Speakers

19. Access the rear speakers by removing the rear side panels or hatch area trim, depending on the model, using a Phillips screwdriver to remove screws and clips.
20. Unscrew the factory 4×6 speakers and disconnect the speaker wires, noting polarity.

Step 6: Install New Rear Speakers

21. Select 4×6 Euro-cut or American-cut speakers suitable for the rear (e.g., Rockford Fosgate HPC1246). Ensure the magnet depth fits the rear mounting area.
22. Connect the new speaker wires, ensuring correct polarity, and secure the speaker with screws.
23. Test the speaker by powering on the head unit, then reattach the rear side panels or trim.

Post Procedure Checklist

• Verify the head unit powers on and all controls (volume, fader, balance) function correctly.
• Check radio reception to ensure the antenna amplifier is powered.
• Confirm all four speakers produce clear sound with no distortion or rattling.
• Ensure front speaker grills (factory or aftermarket) sit flush and do not contact the dash when doors are closed.
• Inspect door panels and rear trim for secure fitment with no loose screws or clips.

Sources

• Clark’s Garage
• Pelican Parts
• Porsche 944 Workshop Manual, Volume 1
• YouTube