w124 (89 only?) head unit upgrade/ fader bypass. how to

[jha2297255]

if you have a becker 25x2 tape player this is how you can bypass fader w.o running new speaker wires on 89 300e

this model doesnt have external amp, so your wires will vary unless you have exact same car

hope its helpful

1 pull off becker faceplate, (mines broken, pull hard)



2 remove lil ash tray thing, depress 2 plastic tabs, pull radio out



3 uh oh, only 2 speaker outs? but4 new speakers? (put new speakers in previous weekend - cut off old ones and solder new ones in 4inch front 5 1/4 rears , have to modify the MB plastic rear 'holder" to fit 5 1/4, i suggest a 4.5 grinder and silicon to glue new ones in)



4 you need the speaker out wires, just the - brown and black, they feed rear speakers



5 at the fader wiring, cut off fader switch, you want only 2 wires out of this bundle


NB using german made kneife wire cutters ensures success!

6 you want these 2 wires, heat shrink tubing seal up all others and stuff them with the 50000 other wires in this area

[jha2297255]

7 you need to extend the 2 fader wires up past gear selector into radio 'hole'



NB solder and heat shrink tubing is better than crimp connectors, learn how to solder

7.1.1 red/green are /extended rear + , move them up to the radio hole like shown below



7.2 all other fader wires get heat shrinked


8 the front speakers are both green/black, one is white plug one is black plug
( note color/L/ R l ocation this is correct) ( i ID the speaker to make future owner/upgrade ez)






NB crutchfield includes 'plugs' that you can plug the euro sockets into and then solder socket to stereo outs, makes no difference but it is easier, not alot of extra length on those wires in radio 'hole'

i would/did duct tape the plug/connector for extra security, you dont want that coming undone (just push together type thing)

9 now you have the original black/brown negatives you cut off euro plugs + the new red/green +

note the color matching for pairs is important

green+brown (green is brown/green stripe extended)

red+ black (red is brown/red stripe extended)



you need these wires from original back of radio plugs

they go with the wires you extended past gear shift like so, wire ties, use em!






10 heres which is which speaker so you know



11 crutchfield wiring harness does make it easier, snaps right into power plug (and locks firmly) so you can solder wires to HU with some breathing room, well worth the $20 premium price

(power harness is red/orange/yellow thing)






now you have 4 pairs of speaker wire and your HU has 4 outputs and you are set! wire according to your HU instructions

tuck the big 'alarm' plug and unused wires into radio hole. blue is antenna remote, cut off plug and wire into HU connector as needed.












Final tips, you can leave fader 'wheel' in place, toss switch part you cut off in trash, maybe use that hole for NOS activation switch when you put it in? (mmmmmm)

the sheating on factory wires is STICKY as sin, yuck

slice sheating with utility knife as needed, dont nick wires (surgical touch here)

thats it! no final pix of new sony HU w ipod cable? i was too excited playing with it!

PPS really sux that we have to host our own pix! takes forever!

[jha2297255]

Finished product! (i know noone was on edge of seat over this but it looks pimping!)

[richard28]

Great post & pics. How did you attach power to the new head unit?

[jha2297255]

crutchfield includes a car harness thats just a plug with 4 wires (ones not used) that plugs into MB power plug and then solder those wires to HU, simple color match up

[jha2297255]

routed ipod cable from back of sony down past shifter below wood, missing some carpet or something in this area currently, works well. on this sony ipod cable DOESNT detach from back, i wanted to detach, drill hole in glove box but its a huge honking plug and wouldve made a big hole, so this works for now.







this is what i did for rear 5 1/4s. the MB plastic 'holder' needs the lip cut off, then enlarge a cutout for the wires on underside and silicon glue the new speaker in, worked out well ( if not aesthetic)

[MTI]

Nice job, but what's the virtue?

I bypassed the fader switch to a new headunit merely by running a few feet of new speaker wire and having the right crimp connectors.

[jha2297255]

almost took that approach, had rear seat out etc. BUT if you can fish wires thru that MB plastic 'wire floor rail' you are skilled!

2 fish tapes, 16 ga fence wire and stillllllllll couldnt get from back to front. nevermind from front to behind radio 'hole'. running wires under benz carpet is hard, you must know something i dont about taking up the carpet.

my way you only need about 2 feet of wire and you dont unbolt seats etc. and it took me about 2 hours to figure out so...ill save everyone else trying to do it 2 hours

[PJ77]

Shame the pics in this thread are missing...