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Stereo Upgrade Info and Links (archive)

[ Follow Ups ] [ 7-series Message Board ] [ Msg. Board FAQ ]

Posted by Thaumaturge on June 28, 2001 at 09:28:33:

Since I have had more than a few emails on this subject, I thought I would post the info again in one place for all you aspiring stereo upgraders.


Max Weinberg's 740i customization (by Sony)from Mobile Entertainment Mag:

The ultimate analysis of the DSP audio system:

Nice info albeit from a 540 owner:

If you speak German or use the AltaVista translator, this 540 site is interesting and full of detailed pics:

Door Removal Instructions for the 740:

740il - Door Panel Removal / Replacement


As with most automotive door panels, the 7-Series panels are held in place by round plastic plugs that snap into holes in the steel doorframe. There are also a series of spring steel clips along the top of the door. Finally, there are two (only one in the driver’s door) plastic clips that snap onto metal spring steel plugs behind the interior handle used to close the door. These provide extra strength.

The door panels themselves are made of a pressed fiber material much like fiberglass. The panel is all one piece.

Significant, steady force is required to remove the door panels. If you are careful, you will not break anything. If anything does break, it will most likely be the little plastic plugs along the perimeter. These are easy to repair/replace.

The whole operation should take about 10 minutes per door once you’ve done the first one.


1. Locate and remove the black plastic screw cover immediately behind the interior chrome door handle. I used a medium sized precision screwdriver. Just push in and tilt up slightly while pulling.

2. Remove the Philips head screw.

3. For rear doors with shades only.
You’ll need to remove the vertical shade used for the triangular window. This is the hardest part. It’s held in place at the top and bottom by clips. The bottom clip is plastic and the top clip is metal. Examine the plastic housing at the top and locate the little notch. The shade actually snaps in first at the bottom and then pivots into place with this notch providing the path. To remove, firmly hold the shade at the bottom and pull up and out. You may need to pivot away from the notch at the same time. If you can’t manage it after a few tries, exert more force at the bottom. It’s pretty tough, but it will come off. Once off, remove the little screw now can now see at the top of the door panel.

4. Unsnap the perimeter plugs. To do this, either use your fingers or a slotted screwdriver to gently pull the panel away from the door. (Careful!! The edge of the panel can be sharp at the front top!! I got a nasty cut on my fingers there.), Start at the bottom and then work up the sides. I used a large size screwdriver being careful not to scratch the paint or rip the closed cell foam seal inside the door. Only push in the driver about 1”. It was easy to simply run the shaft of the screwdriver along the outer edge and wait for each plug to pop out. (I did have one panel that broke at the point where the plugs slide in. A little hot glue held the plug in place when I put the panel back on. Worked great.)

5. With all the perimeter plugs popped off, you are now ready to remove the panel. Firmly grab the door panel at the top and pull the black leather top section toward the interior of the car. Metal clips hold on this part. Hopefully, the top will unsnap easily. If not, a little more force may be required. If it still won’t completely separate, forget it and move on to the next step. It will come off then.

6. With or without the top fully disengaged from the clips, grasp the entire panel firmly at the bottom and at the door pull handle. Pull straight up and a little out at the top. The clips behind the door pull handle will disengage once the door has been lifted about 1.5” – they slide up. You will also clear the door lock at this height.

7. At this point you will need to feed the chrome door handle through it’s opening by twisting it gently.

8. Now disconnect several wiring harnesses. The bottom underside door light (see below), the window switch, the speaker connectors (1 or 2), and the ashtray light. Each harness only fits one place; so don’t worry about mixing them up. The bottom underside door light can be a pain to remove. It is pressure fit and needs to be pried out to expose the wiring. Carefully pry it out starting at one end with a small flat screwdriver taking care not to poke or cut the leather. (If you do, it won’t show anyway.) Once pivoted about 30 degrees, it can slide out. If it won’t budge at one end, try the other. The wiring harness plugs in at the end.

9. The panel should now be free from the door.

To put it all back again, make sure the plastic plugs are all there and are straight. They also have black little fabric/rubber washers that like to fall off.
1. Remove the door pull handle plastic clips from their plugs by squeezing the metal with a pair of pliers while pulling the clip. Note their orientations on the metal clips. Once you have the clips, slide them back in place on the panel before trying to put the panel back on the door. Note that the flared openings on the black plastic clips face out to allow them to slide back on to the metal plugs easier.
2. Now you’re ready to plug all the wires back in. Just feed the bottom lamp harness into its hole and reconnect after the panel’s back on.
3. Slide chrome door handle back through. Straighten it later.
4. With a little finesse and a few well-placed pushes/slaps from your hand, the door panel will be back on.
5. Remember to replace the little screw at the top of rear doors.
6. Now you can replace the rear vertical shade by snapping it in at the bottom and pivoting it over the top clip.
7. Replace the screw and plug behind the door handle.
8. Remember to plug in and replace the bottom lamp wiring harness.
You’re done!!

Wiring Pinouts for the 740 w/DSP amp:

740il w/DSP Premium Sound Amplifier Technical Info
Amp located behind CD Changer in left rear compartment of trunk.
There are 3 modular connectors on the amp and one “coax” lead.
All modular connectors use a locking mechanism that either slides (15-pin) or pivots to raise the connector.

Remember to check your polarity to avoid out of phase problems after new speakers go in.

Information believed accurate, but I take no responsibility for damage resulting from its use.
The pinouts for the 15 pin connector:
These are large pins, connector closest to trunk and rear of car.

1. Subwoofer Rear Deck, Left +
2. Subwoofer Rear Deck, Left Center +
3. Left Rear Door Woofer -
4. Radio on/antenna trigger signal (12v)
5. Right Rear Door Woofer +
6. Subwoofer Rear Deck, Right -
7. Subwoofer Rear Deck, Right Center -
8. 12 V Power Source
9. Subwoofer Rear Deck, Left -
10. Subwoofer Rear Deck, Left Center -
11. Left Rear Door Woofer +
12. Right Rear Door Woofer -
13. Subwoofer Rear Deck, Right +
14. Subwoofer Rear Deck, Right Center +
15. Ground

The pinouts for the 18-pin connector are:

1. Not used
2. Low freq. negative (-) signal - Transceiver/charging electronics
3. Not used

4. Not used

5. I-bus Signal Line - Splice X18344
6. Not used
7. Not used
8. Right Preamp Output –
9. Left Preamp Output –
10. Not used
11. Low freq. voltage (+) signal - Transceiver/charging electronics (DSP)
12. Not used
13. Telephone mute signal - Transceiver/charging electronics
14. Not used
15. Telephone ON signal - Transceiver/charging electronics
16. Not used
17. Right Preamp Out +
18. Left Preamp Out +

The pinouts for the 26 pin connector are:

1. Left Front Woofer +
2. Left Front Woofer -
3. Not used
4. Right Front Mid-range -
5. Left Front Mid-range +
6. Not used
7. Not used
8. Not used
9. Right Front Mid-range +
10. Left Front Mid-range -
11. Right Rear Mid-range +
12. Right Front Tweeter +
13. Right Front Woofer +
14. Left Front Tweeter +
15. Left Front Tweeter -
16. Left Rear Mid-range -
17. Not used
18. Not used
19. Left rear mid-range speaker/tweeter +
20. Not used
21. Not used
22. Not used
23. Not used
24. Right rear mid-range speaker/tweeter -
25. Right Front Tweeter -
26. Right Front Woofer -

If you need more info, email me.

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