Tig: Add Radio wiring FAQ discussion tips (fader shortcut, fuse panel, swapped power)

2026-08-13T22:06:00Z

Add Radio wiring FAQ discussion tips (fader shortcut, fuse panel, swapped power)

← Older revision		Revision as of 22:06, 13 August 2026
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	An '88 ran this layout for two years with no failures.		An '88 ran this layout for two years with no failures.

			== From the discussion ==
			Discussion thread: [https://forums.mye28.com/viewtopic.php?t=105944 Radio wiring FAQ discussion]. Shagrath later confirmed the write-up above is correct as posted. A promised photo set and a non-premium-sound follow-up were never added.

			Useful additions from that thread:

			* The factory radio power harness is already fused. You do not have to move the head unit onto the auxiliary fuse panel. If you want to anyway, see [https://forums.mye28.com/viewtopic.php?t=53571 t=53571].
			* Swapping memory (constant) and switched power is the most common install mistake — the radio turns on but loses presets, or will not turn on at all.
			* Factory wire colors in the car can disagree with the ETM if a previous owner has been in there. Confirm with a meter, not just the color.
			* Cars without premium sound are a simpler rewire; this page is the premium-sound / factory-amp case.

			'''Keep-the-amp shortcut''' ([[lmc337]]): unplug the fader wheel, connect the aftermarket head-unit speaker '''positives''' to the matching fader-output pins (Chip Baines's old stereo-upgrade page had the colors; the site is gone), and leave the head-unit negatives disconnected / tied off. The factory amp stays in the circuit, no speaker wires are cut, and a stock head unit can go back in in minutes. Two-plus years with no speaker issues. Caveats: the radio can cut out on the brakes, especially with an extra brake light and on wet days, and an old fuse has been known to pop.

			Chip Baines's stereo-upgrade notes used to live at eabjr.com (dead, same as the OBC page).
	[[Category:Tech FAQ]]		[[Category:Tech FAQ]]

Tig: Add radio wiring Tech FAQ from forum t=91386

2026-08-13T21:57:37Z

Add radio wiring Tech FAQ from forum t=91386

New page

By [[shagrath]], Mon May 09, 2011

Original thread: [https://forums.mye28.com/viewtopic.php?t=91386 Radio wiring write up]

How to install an aftermarket radio on the factory harness without rewiring the whole car. This walkthrough uses diagrams 6500-0 and 6500-1 (pages 99–100) from the [https://forums.mye28.com/manuals/1987-1988%20BMW%20528e%20-%20Electrical%20Troubleshooting%20Manual.pdf 1987–1988 BMW 528e ETM], '''with premium sound'''. Cars without premium sound are a more straightforward rewire. Ignore all fader-switch wiring.

Wire colors below are ETM colors: VI/GY is violet/grey, RD/WT is red/white, BR/BK is brown/black, and so on. See also [[Electrical]] for the rest of the ETMs.

__TOC__

== Aftermarket harness colors ==
These are typical. Confirm on your unit.

* '''Red''' — main (switched) power
* '''Yellow''' — memory power (keeps presets; does '''not''' turn the radio on)
* '''Black''' — ground
* '''Blue''' — remote (aftermarket amp)
* '''White''' — dash-light dimming or power antenna
* Speaker pairs: purple, grey, green, white; the same color with a black stripe is the (−) side

If the radio turns on but will not keep memory, the red and yellow wires are backwards.

== Power and ground ==
Using diagram 6500-0 (page 99):

# Find the '''VI/GY''' (violet/grey) wire that changes at a connector to '''VI/WT''' (violet/white). This is main power. Splice the aftermarket '''red''' wire to the VI/WT side, omitting connector C216. The VI/GY in the car is looped and looks confusing — tap the part that goes back into the dash.
# Find the '''RD/WT''' (red/white) wire. It will be connected to a yellow wire. '''Ignore that yellow wire.''' Splice the aftermarket '''yellow''' memory wire into RD/WT (unless your radio uses a different memory color).
# There are two factory white wires. One runs with the antenna cable (raise/lower). You can try splicing it if your radio has a power-antenna output; many people use a separate switch instead. The other white wire connects to '''GY/RD''' and goes to the light switch for auto-dimming. It can be left unused.
# Ground is '''BR/BK''' (brown/black). Splice the radio's black wire here. If BR/BK is already tapped to a solid brown (BR), splice to that.

The radio itself will now power up. Speakers are the rest of the job.

== Speakers — run new wire up front ==
# Run new equal-length wire to both front speaker tunnels for '''both''' the front and rear channels: right front/rear on one side, left front/rear on the other. Tuck it behind the kick panel and through the glovebox. Leave at least 4 inches in each front speaker tunnel. You do '''not''' run new wire to the back of the car.
# Diagram 6500-1 (page 100): wire the front speakers. On factory E28 fronts the two sides are opposite each other on the speaker. '''GY/GN''' (grey/green) is the tweeter. Remove the two factory front speaker wires and splice the new wires from the radio (the pair for that speaker — remember you ran four wires into that tunnel). Repeat for the other side. The fronts are now entirely on aftermarket wiring.

== Rear speakers — use the factory amp runs ==
The factory amplifier wiring already goes to the back of the car. Use it as the rear speaker run.

# At the right front speaker, diagram 6500-1 shows '''GY/BR''' (grey/brown) and '''GY/WT''' (grey/white) going to the amp. Splice the two leftover radio wires (the rear channel for that side) to those two. One side of the connector looks messy; splice it and move on.
# The left side is the same idea with '''GY/VI''' (grey/violet) and '''GY/RD''' (grey/red).

== Bypass the trunk amp ==
Unplug the amp in the trunk and pull the harness out far enough to work. Cut the wires listed below and splice matching letters together (A to A, B to B, C to C, D to D):

{| class="wikitable"
|-
! Pair
! From amp harness
! To amp harness
|-
| A
| GY/BR (grey/brown)
| BK/WT (black/white)
|-
| B
| GY/VI (grey/violet)
| BK/VI (black/violet)
|-
| C
| GY/RD (grey/red)
| BK/RD (black/red)
|-
| D
| GY/WT (grey/white)
| BK/BR (black/brown)
|}

Tuck everything away. The factory amp is out of the system; the rears are driven directly. This can be put back to stock — no cutting of the fader switch, and the factory wiring is still in the car.

An '88 ran this layout for two years with no failures.
[[Category:Tech FAQ]]

Radio Wiring - Revision history

Tig: Add Radio wiring FAQ discussion tips (fader shortcut, fuse panel, swapped power)

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