Naturally I wanted to keep the radio in the car, but be able to play music through my phone.  The Becker Mexico does not have a line in capability, so I used the iSimple Tranzit Blu HF.  This is the same as on my 450SLC and other cars.   This unit is essentially a box the size of a deck of cards.   It plus into the antenna source of the radio, transmitting an FM signal onto the antenna wire, rather than into the air.  This provides a much cleaner signal than most FM transmitters.   The regular antenna plugs into the unit, so when it is disabled, regular radio reception is possible.   There is a small control button and a microphone for bluetooth calling.

I’m glad I bought a few of these units a few years ago when they were on sale, as they no longer seem readily available.   From what I gather, there are three variants, the ISFM23, ISFM2351 and the ISFM2381.    The first two seem discontinued, and the latter is always listed as out of stock.   This is a shame, as its a great solution for classic cars.

As with the other cars, I also put in a couple of USB charge ports so I could charge my phone and not leave the ashtray hanging open.

I didn’t want to modify the car in any way, so I simply unplugged the power feed to the cigarette lighter and used it for the Tranzit Blu and the USB charging ports.  Luckily I even had a section of MB wiring harness from a W126 washer bottle pump that plugged right in, thanks to my old 420SEL parts car.

I wired it up so the USB charge ports were on switched power like the cigarette lighter would have been.   The Tranzit Blu is wired in the same way, but a relay only powers it on when the Becker is switched on.  I did this by using the antenna trigger to enable the relay.   The relay then powers the Tranzit Blu and also trigger the antenna.  I’ll probably add a hidden switch to control the antenna.  I often park under a hoist which would damage the mast if I forget to switch off the radio.

This job was a little harder on the W116 than on the W123 or W126.  When the ashtray is removed, There is a backing plate that prevents access to behind the radio.   The job is still quite straightforward, but a little fiddly.

I built the wiring harnesses I needed outside the car, and then proceeded to remove the Becker.  The Becker radios have their own mounting system based on mounting hardware that is tightened by a large flat head screwdriver.    I also had to remove the carpet section under the glove box to get access to the Becker amplifier (for the antenna trigger) as well as under the steering wheel to mount the control button on the underside of the steering column.

Testing everything without putting it all back together properly revealed some strange behavior I could not work out.   I was only after I got my power probe out that I realized my mistake.  I had assumed that since the brown wire went into one side of the plug, it was the ground.  The wires were probably crossed inside the plug.   Not only did that cost me an hour of time, but I shorted out my Tranzit Blu.   That was really frustrating since these are now hard to get.   I had one more that was earmarked for the 560SEL that I had to use.

Once I sorted out my mistake, the rest of the installation went fairly smoothly.  I was able to get the Becker back in and correctly in the dash.  I also installed a missing plastic retainer for the glove box insert which is the same as on the W126, another part from my parts car.

The install was in time for the drive down to Canberra for the ACT German Car show. Having bluetooth audio through my Becker made the drive much better.

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I got the radio back last year, and finally found time to re-install it.    I had also seen on Instagram where anther W123 owner had installed a USB charge port meant for an E36 BMW in place of the factory fader.    My factory fader is still working, but my 240D has two switch blanks on the top console, which is the perfect spot for a charge port.   The USB charge port was quite expensive, but it looked like a really good solution so I ordered one.

To power the Becker 596, I also planned to install another Tranzit BLU Bluetooth Box.   This is the same solution I have used in my 560SEC, 300TE and 450SLC.   I’m very happy with it.   The Tranzit BLU is a small box, about the size of a deck of playing cards that provides a FM signal directly on the antenna wire.   This makes it far less susceptible to interference.  It also provides a handsfree option for calls.

Normally the Tranzit BLU is controlled by a hidden button.  However, I had the idea of using a factory sunroof switch in the other blank switch location instead.   I didn’t have a W123 sunroof switch in my box of parts, but I had one for a W116 or W107, which is good enough to test with.

The installation was pretty simple.  I use the connector for the cigarette lighter to power the USB charge port.   The spade connectors that came with the charge port were too narrow, and not quite long enough so I made some extensions.   In testing the USB charge port, I was also able to easily pull off one of its connectors, so I crimped on a new one.

Since the USB charge port is designed to be added to an E36 BMW, it has been designed to piggy back off another accessory.   Therefore, it already had power and ground connectors for the Tranzit BLU.   I used a relay to trigger the Tranzit BLU from the Becker Antenna trigger.   That relay then powers the Tranzit BLU and also triggers the power antenna.

Instead of the button that comes with the Tranzit BLU, I wired in the sunroof switch.  I used a multimeter to work out which of the four pins are activated when the switch is pressed forward.   Essentially the way the switch works, is when it is pressed, it joins power to one side of the motor, and ground to the other side.   Thus, pressing the switch the other way reverses these connections, allowing the motor to run in reverse.   I assumed for this purpose I just needed to make the connection to trigger the Tranzit BLU.  Turns out I was wrong.

I wired it all up and did a quick test of the system.   I was able to pair my phone and play music through the Becker 596.  However, the switch did not work.   I tried a few more pin options to no avail.   I had assumed that the switch was ‘dumb’ and just made a connection to trigger a press of the button.  However, it was looking like that was not the case.   I got the Tranzit BLU switch and connected that to a multimeter.   On very high resistance settings, I was able to trigger a change in resistance when pressing the button, but it wasn’t constant.    Given there appeared to be more to this button than I anticipated, I gave up and put the switch blank back in place.    The Tranzit BLU button is now on the steering column out of sight like in my other cars.

Despite the failure of using the sunroof switch to power the Tranzit BLU, I am very happy with the setup.   The correct Becker is back where it should be and I can play music through my phone and make and receive phone calls.    I am taking the 240D on its first road trip this weekend, so having music will be great.   The install is totally reversible with no factory wires cut.

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After driving around for a few weeks, I realised I needed to make a few changes.  Overall, I was really happy with the system, except for the following:

• USB charging ports were no longer working
• Distortion in music with strong midrange at medium to high volume
• The radio worked at position 1 of the ignition switch, but the bluetooth module required position 2.

The USB ports were working fine until I put the trim back in, so I assumed I had accidently pulled out the socket during the re-install.    I also figured I could improve the distortion by playing with the amplifier gain settings.    It is never going to be distortion free due to the small speakers in the car, but I thought I could get it better.

The last one, I assumed I had plugged into the wrong pin on the X30 connector.    To get to all this, the under dash panel, side kick panel and carpet must be removed.   That provides access to the X30 connector and the cover for the various control boxes where I had installed the amp.

Some testing with my power probe quickly confirmed the issue with the USB ports.   The connector between the X30 harness and the US transformer was no longer working.   Instead of just replacing it, I added another 20cm of wire on both the positive and negative so it wouldn’t be under pressure during the install.

The X30 wiring proved to be a big more complex.   I was using pin 5, which is supposed to be hot in start, run and accessory positions.   I had assumed this meant position 1, 2 and 3 on the ignition switch.   Turns out it means position 2, both when the car is running and when it isn’t, and the start position (3).

I swapped over to pin 1, which is hot at all times.   I didn’t want to create a drain on the battery, so I left the USB cables on pin 5, but harness for the radio accessories is controlled by a relay.   The relay is energised by the antenna signal from the radio.   That in turn switches on the amp, triggers the antenna and powers up the Tranzit Blu.   Given the presence of the relay, it should not be drawing current with the car off.   The only thing that is actually using power is the Tranzit BLU, which has minimal power needs.

Next was to look at the distortion.   I found that it sounded better with the amplifier gain turned up more.   Probably because the signal from the Becker was from a the line out module.    Since I am using a single left-right input, I wasn’t able to adjust front and rear gain separately.   This is a shame, as the rear speakers are larger.

After driving the car some more, I was really happy with the improvements.   The Bluetooth function powers up when the radio does.   The distortion is much reduced.   And the USB ports now work!

There was one more thing left to do.   Investigate if it was possible to have the music play from my phone as soon as it connects to the Bluetooth in the car.    I wanted to be able to leave my phone in my pocket and it would just play.   The Tranzit Blu has a button to advance the track and answer calls, so the phone is not necessary to control things.

I found there are more possibilities on android.   For an iPhone, there is an Apple app called ‘Shortcuts’.   This allows simple if/then/else logic to automatic various functions.

The left hand screenshot shows how simple it is to create the function.     Unfortunately, it does not run without any user input, as the script generates a pop up that asks the user if it should run.    This is better than going through the menus on the phone to select music, but not ideal.   The popup is shown on the right.

The installation is now complete.   I’m really happy with the outcome.  I have the look and feel of the original Becker, with the Bluetooth FM injector for modern functionality.

The post W126 Becker Radio install – part 4 appeared first on .

The first step was to properly organize and tidy up the wiring.  I wanted a neat install, and to hide all the wires out of the way.   The Alpine amplifier I am using is small enough I could tuck it in with some other control modules in the passengers foot well.

I mounted the amp with the back face up so I could adjust the dip switches if required.   I didn’t have a great way of mounting it without drilling, so I used some stick on Velcro.     Before I re-installed the under dash panels, I had two further tests to perform.   The first was to check the hands free calling feature.   Last time I was testing the system, it was after 11PM, so it wasn’t really appropriate to start calling people.   I’m glad I did, as the previous microphone from the Alpine head unit did not work with the Tranzit BLU.

The Tranzit BLU comes with its own microphone, but I had planned to use the Alpine mic as it was already installed.   That meant I needed to remove the radio to feed the cable for the microphone to the drivers side of the car.   In doing that, I discovered a problem.   I had cable tied the RCA cable to keep it away, so when I tried to pull out the radio there was no slack in the cable.

Something had to give, and that was to pull the line out module off the back of the radio.   It has a screw holding it on, but only one.   That mean it levered outwards and bent one of the pins.   Luckily I was able to remove the module, bend the pin back, and re-install it.   It also meant I had to cut off all my cable ties, add more slack and then re-cable tie that section of the install.

My second test was to try the high pass filter for the rear speakers.  In the end I set it at 60Hz.   With that done, I was able to start putting things back.

The plastic retaining screws for the cover for these control boxes were long lost on my car.   Luckily, the parts car had one of them which I used.   One of the connectors for the Tranzit BLU was loose, so I sniped it off and replaced it.

The two side panels were quite easy to re-install.   The one against the console just slots into place.    The panel against the side of the car slides in from the rear.   It is then further secured by the screws for the bonnet release.

The hardest panel to re-install was the passengers side under dash panel.   Getting that back into place was a real pain.   I set it up so the USB ports were just poking out between that panel and the console.   That leaves them accessible for my phone in its windscreen mounted phone holder.

On the drivers side, the under dash panel was easier to use.   I noticed when putting it on the ‘scoop air’ vacuum pod was damaged and needs replacement.   These are now NLA, but diaphragms are available from aftermarket sources.   That will be a job for another day.   let the control button just poke out on the opposite side to the USB ports.   I also had the microphone coming out on the other side of the steering wheel.

Once I had the radio installed, I took the car on a test drive to see how it all worked.   Overall I am really happy with my Becker radio install.   Now I have the Becker installed, its obvious how out of place the modern Alpine head unit looked.   The Tranzit BLU is a nice way of bringing a period radio into the 21st century.   I prefer it to modifying the radio to support Bluetooth.   I plan to keep this car for the long term – and who knows how long Bluetooth will be the primary technology used for this type of streaming.    The sound is very good through the amplifier and I was able to adjust the bass/treble controls on the Becker 1402 to my liking.

Through my testing, I have found two issues I will need to address.   Firstly, the USB ports are now no longer working.  I suspect re-installing the under dash panel pulled out a connector.   This is a pain because it was the hardest one to get in.   Secondly, the Tranzit BLU is not powering on when the ignition key is in the accessory position.   It only works in start and run (i.e. position 2 and 3).    I neglected to do testing in the accessory position which was a bit of a miss.   The problem is likely that I have a pin in the wrong spot connecting into the X30 power block.   I have to take the dash panel out anyway to fix the USB ports, so I will look at this at the same time.

In a totally objective view, I’ve spent hundreds of dollars on my Becker radio install to have less functionality than before.    I don’t see it that way though.   The Becker works really well in the dash of the W126 and with my improvements, I have a system I really like.

I’m going to use this system for a while before I move onto my next Becker radio install and upgrade – on my 450SLC.

The post W126 Becker Radio install – part 3 appeared first on .

I decided to use two X30 harneses for the install.  I had four available plugs on the X30 power block, so it kept it neater if I used two.   The main purpose of the first one was to connect my USB ports.   I also used one of the ground wires for the Tranzit BLU.   For this application I only needed pin 5 and pin 1.   I removed the wire for pin 3.   The USB ports will be available when the car is in the accessory position, starting or running.   I thought about making them live all the time, but I am not sure of any minor current draw from the USB port module.   As this car is not used daily, I don’t want any current draw.   No more driving around with the ashtray hanging open.

The nice thing about this setup, is that I can simply unplug the module if I ever need to.   The ground wire for the Tranzit BLU will have a plug for the same purpose.    The second X30 harness will power the relay which controls turning on the amplifier, and powering the Tranzit BLU.   I don’t want the Tranzit BLU running with the radio switched off, as my phone will pair with it and it will be useless.   The relay will be triggered by the wire from the Becker that normally controls the electric antenna, but the relay will now fire all these things.   The amplifier has a trigger wire for a second amp or antenna, so I will use that one for my power antenna.

I originally cut this harness shorter as the length required is only from the X30 power block to the footwell.   I forgot that the wires from the X30 exit forwards, so I had to join it back together again.   In any case, I now have the X30 wiring in place and two spots remaining.

I mounted the relay in the passengers foot well using an existing screw.  It was probably for the previous Cobra alarm.   Next step was some basic tidying up of the wiring so I could see what I was working with.   That meant using some cable ties of the various wiring groups like front speakers, rear speakers, relay triggers etc.

To test the system, I needed core power to the amplifier.   There was still a wire from the battery to this area of the car from the old Cobra car alarm.  I was able to repurpose it with a new 15A inline fuse.   Once done, it was a fairly simple matter of plugging the various connections together for a test of the system. Before that test, I had to configure the amplifier.   There are some dip switches on the back where I set the input for two channel.   I also turned on the high pass filters – for the test I used the 60Hz option for the fronts and the 80Hz option for the rears.

Powering it on, it all seemed to work properly first time.   Normally when I do projects like this, there are issues I need to address.    Before I paired my phone, I was able to listen to the radio as normal.   Once I paired my phone I was able to play music through the system.   It sounds pretty good!  I adjusted the gain levels slightly on the amp while testing a wide variety of songs.   I also wanted to make sure the left/right speakers were installed properly.   Queen’s Bohemian Rhapsody is useful for this.   The small button used to control the Tranzit BLU also worked correctly.   When in music playing mode, pressing it advances to the next track.   By now it was 11:30PM, so I didn’t test the handsfree calling function.

Since the music from my phone is going through the FM signal, its not perfect.   It is very good though, thanks to injecting the FM signals right into the antenna cable.    The Alpine amplifier means the Becker is easily able to power four modern speakers.

The USB ports were also working correctly and powered my phone without issue.

Next steps from here is to mount the amplifier properly and tidy up the wiring.   I may also play with the high pass filter a bit more.   80Hz might be a bit ambitious for the 6.5″ rear speakers in a W126.   Then all the trim needs to be re-installed.

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