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Aftermarket Head-Unit Installation for the Compleat Idiot
GLX folk,
This is a note on installation of an aftermarket headunit into an
(early?) 1998 Jetta GLX with Bose amplifier system, for the Compleat
Idiot. Note that most of the instructions apply as well to the
replacement of a normal "premium" headunit as well - the only
difference being the (-) terminals on the speakers and the power to an
outboard amp.
Note that VW evidently did change the wiring harness during in the
1998 model run to hook up the dreaded "K wire" for diagnostic
purposes. Please refer to the GLX mailing list archives for the note
from Matt Cleland dated 31 Aug 1998 with the subject line:
"RE: K-wire & indash stereo not a problem on *all* 98s - evidently"
for more information on the K wire. The ListQuest server is amazingly
useful here ( http://www.listquest.com/lq/search.html?ln=glx ).
In any case, this note is for your information only. I assume no
responsibility if you damage yourself, your car or your new audio
system, your mileage may vary, etc etc.
Tools needed:
1) small soldering iron
2) heat gun (or hairdryer)
3) small flat blade screwdriver
4) medium Phillips screwdriver
5) electric drill and assorted metal drill bits (for CD changer
installation)
6) crimping tool (for CD changer power snap plugs)
Supplies needed:
A) aftermarket headunit for installation, plus application-specific
installation materials (e.g. DIN insertion sleeve, radio wire
harness, etc.)
B) powered antenna adapter for FUBA antenna
C) Metra adapter for VW wiring harness (the number is either 40VW20
or 70-1784, I couldn't verify, but there is only one)
NOTE: if you buy your radio from Crutchfield, you get items A, B
and C inclusive; I'm not a Crutchfield shill, just a very
satisfied customer
D) solder
E) heat-shrink tubing in 2 diameters: one just large enough to fit
around the harness wires (ca. 16 gauge) and one about double that
diameter
F) 2 crimp-on insulated power snap plugs (if you are also
installing a CD changer)
G) wire-ties
Diagram of Metra adapter (view of pins in adapter; mirror image of
plug holes in VW wiring harness):
-----------------
__| 1 3 5 7 |
|__ | Section II - Speaker connections
| 2 4 6 8 |
|-----------------|
| 1 3 5 7 |
__| | Section III - Power and control connections
|__ 2 4 6 8 |
-----------------
List of wiring harness connections for early 1998 Jetta GLX (and
possibly others):
Section II, pin 1: right rear speaker (+)
Section II, pin 2: right rear speaker (-)
Section II, pin 3: right front speaker (+)
Section II, pin 4: right front speaker (-)
Section II, pin 5: left front speaker (+)
Section II, pin 6: left front speaker (-)
Section II, pin 7: left rear speaker (+)
Section II, pin 8: left rear speaker (-)
Section III, pin 1: (open)
Section III, pin 2: (open)
Section III, pin 3: amplifier power (black wire; SEE NOTE)
Section III, pin 4: ignition (switched) +12VDC power
Section III, pin 5: (open)
Section III, pin 6: illumination
Section III, pin 7: battery (unswitched) +12VDC power
Section III, pin 8: chassis ground
NOTE: Section III, pin 3 is also used in some models as a lead
to a VW diagnostic computer, and 12VDC will give it an
electronic lobotomy (serves 'em right, I say). In the
harness that I have, a black wire came from the Bose
speaker wire bundle and is connected to this contact,
and it is the power pin to the external amp.
Your mileage may vary. Be careful.
Procedure:
1) Build the wiring harness adapter, using the Metra adapter and your
headunit's plugs, making the following connections:
HEADUNIT CONNECTION ADAPTER CONNECTION
----------------------------- ------------------------------
a) antenna power a) power lead on FUBA adapter
b) illumination b) Metra pin III/6
c) amplifier switched power c) Metra pin III/3
d) ignition switched 12VDC d) Metra pin III/4
e) constant battery 12VDC e) Metra pin III/7 AND female snap
plug (for CD changer)
f) chassis ground f) Metra pin III/8 AND female snap
plug (for CD changer)
Note on connections e) and f), you are going to make "pigtails" for
the 12VDC/grnd take-offs (if your headunit harness doesn't already
supply them). These will be used by a CD changer. Be sure to use
the insulated female part of the snap plug here to avoid shorts.
I like to make these joints using a butt solder joint and cover it
with heat-shrink tubing. It makes for a clean, compact adapter,
and the more compact, the better, as this all has to fit into a
small space. I won't go into basic soldering techniques here. It
really depends upon how much of a neat-freak you are, and how
scared you are that the adapter will come apart like a cheap suit
when you stuff it into the dash. Better safe than sorry.....
2) Continue building the wiring harness adapter by taking all of the
radio's negative (-) speaker wires and isolating them from the
harness and everything else. I just folded back each negative lead
and used heat-shrink again. If you can, you may want to simply
remove all negative leads from the radio's plug, but be sure to
avoid any possibility of shorting to the chassis or to each other.
3) Complete the wiring harness adapter by hooking up the positive (+)
speaker connections:
RADIO CONNECTION ADAPTER CONNECTION
----------------------------- ------------------------------
g) right rear speaker g) Metra pin II/1
h) right front speaker h) Metra pin II/3
i) left front speaker i) Metra pin II/5
j) left rear speaker j) Metra pin II/7
Also, crimp the male snap plugs onto your CD changer harness.
Take a moment to hook up the adapter to the headunit, line up the
plugs and antenna power adapter, and visualize the adapter going
from the back of the headunit toward the driver's side of the
dashboard. Squeeze the wires together into a nice neat bundle and
wiretie them together in this configuration. This will greatly
facilitate reinstallation of this mess of wires into the dash.
Adapter is now complete.
4) Remove your present radio. If it is the OEM Bose headunit, you
will need special tools (not the usual DIN loops) to remove it.
Have a dealer or other VW specialist do it if you don't have the
tools. This can be done in advance, of course.
5) Remove the battery ground strap. Remove the ashtray (use the
little button on the bottom), the trim panel around the climate
control knobs (use the small flat bladed screwdriver), the switch
panel assembly (remove 6 Phillips screws: two in ashtray opening
and 4 below the trim panel) and finally the climate control
assembly itself. Let the switch and climate control assemblies
hang out of the way as much as possible. This all sounds a little
complicated, but actually takes only about 3 minutes, even less
with a power screwdriver.
6) If you are installing a CD changer, you will need to do these
additional steps:
6a) Remove trim pieces from passenger side of car: base of rear seat
/ rear rocker panel interior (pop up seat bottom and fold down
seat back for access), front rocker panel, base of A pillar and
glove box. In that order. Some of these pieces are "self
destruct on removal" pieces, especially the rear seat trim
piece, so be careful. Also be careful around the rocker panel
area if you have side airbags: the sensors are here, so don't go
using the 8 pound sledge for trim R&R.
6b) Pull down the foam under-dash trim for access to the passenger
side dash area. You needn't remove any fasteners to do this.
6c) Snake the CD cable from the headunit hole back to the trunk,
snapping it into the existing cable guides which you exposed by
removing the trim. Don't try to be a hero and snake the cable
in the route used by the OEM wiring - this feat is nearly
impossible. Instead, use the space behind the climate
control. Follow along under the passenger side dash, down the
bottom of the A pillar, along the rocker panel area and into the
trunk.
6d) Replace all trim removed in step 6a in reverse order.
6e) Whew. Have a cold one, preferably an import or a microbrew.
You have just finished the most difficult part of the
installation.
7) If yours is a DIN headunit, put in the DIN attachment sleeve per
the manufacturer's directions. If not, you are on your own to make
sure that your headunit fitments are correct.
8) Pull the antenna wire, the 2 VW wire harness plugs and the CD cable
end (if you are doing the CD thing) out of radio opening, leaving
the OEM CD changer plug in the dash (it's the pink one with 10
contacts on it). Hook up the adapter that you have made to the
harness and antenna wire, then to the back of your new headunit.
If you are installing a CD changer, go to the trunk and plug it in
as well. Test the radio (and changer) by briefly hooking up the
ground strap and verifying that everything is working. Pat
yourself on the back. Remove the ground strap again.
9) Stuff the whole mess back into the dash (this is the point where
you'll be glad you built a bulletproof harness adapter), reaching
under the radio opening to guide the harness into the area behind
the seat heater controls. Also be sure that the antenna stays
connected to the rear of your headunit and that the rear headunit
mount engages with the mountpoint in the dash. Take your time.
Use your feet if necessary :-). This will go much easier if you
did the final part of step 3.
10) Replace all components and trim removed in step 5 in reverse
order.
11) Mount the CD changer in the trunk according to the manufacturer's
directions. The driver's side "wall" is a good place, but if you
choose this location, be sure to move the locking system vacuum
pump (in a little styrofoam pod) out of the way before you start
drilling. In any case, be sure to remove any carpet or trim to
see what you are drilling into. Don't add any additional holes to
the gas tank, any wiring bundles, vacuum hoses, etc. You get the
picture, right?
Hook up the CD changer harness.
12) Reconnect the ground strap. Reset the clock.
You are done. Enjoy (with amazement) how well a modern aftermarket
headunit will drive that Bose amplifier and speaker system.
Best regards,
Willie Anderson
1998 Jetta GLX: Porcelain Blue / Biber Beige
Blaupunkt Sydney Headunit / 10 CD changer / Bose
Locking gas door