Handsfree and car radio installation: instructions for a successful installation

In many new cars, car radios are connected to a navigation system and so well integrated that they can not be replaced. For many a disadvantage, but it should also be noted that modern car radios take on more functions and thus also connect more technology in the vehicle. This works only through a complete integration with the technology.

Older cars or cars without special equipment, often have a DIN slot that allows you to use radios from almost all manufacturers. Connections are also becoming more and more standardized, and many manufacturers of car radios, as well as vehicle manufacturers, use the standardized ISO pin assignment. This allows a car radio to be replaced without special knowledge or special tools.

To do-it-yourself.De we show you with instructions how to completely easily install a car radio or hands-free system can.

1. Removal of the old car radio

If you have problems removing your radio, a rear additional bracket could be the problem.

For the dismantling of the old car radio a special unlocking tool needs. This is included in the scope of delivery and should be well kept. There are two main types of connections.

there are brackets that are inserted into existing holes and release clamps or plates that release and at the same time support the removal of the car radio with a small nose.

If the appropriate tools are no longer available, suitable nails are required for the first variant, and for the second narrow screwdriver helpful. In workshops, however, such aids are part of the basic equipment and can be helped quickly.

Tip: if the car radio cannot be removed even with the appropriate tools, an additional bracket in the rear area could be the cause. If car radios are particularly heavy or if the dashboard does not offer sufficient support, the radio is held in place by an additional screw connection on the rear side. This can be accessed either through the glove compartment or awkwardly underneath the dashboard.

2. Installation of the new radio

be sure to disconnect the car’s battery to avoid a short circuit.

Own car and car radio ISO connectors, no further tools are needed. Even if the manufacturers use their specific connections and the appropriate adapters are used, the installation is done without any additional tools.

However, especially in older vehicles there are no plug-in connections and the connections were screwed, plugged or soldered. Now, in order not to damage the new car radio, there are one-sided or open ISO connectors.

These have a suitable ISO plug and open cable ends to connect them to the cable ends by means of a screw or crimp connection. Special care should be taken here, as a short circuit can lead to a cable fire.

  • The disconnect the vehicle’s battery: to make sure that no short circuit can be created during installation.
  • separate the mounting frame from the radio and slide it into the slot. It has many small lugs that must be bent outward with the screwdriver, to give the radio a tight fit.
  • hold the car radio in front of the slot and attach the connectors.
  • Radio slide into the DIN slot and make sure that no cable is pinched.
  • reconnect the battery and check the radio for correct function.

3. Car radio connectors and automatic antenna

If your car has a DIN slot, you can use devices from many different manufacturers.

Two groups of connections can be distinguished: inputs and outputs on the radio. the inputs include the power supply and the antenna socket (connections for CD changer, hands-free system and external music sources are optional), the outputs include the speaker connections and the preamplifier output.

When a cd changer or an amplifier is to be controlled, it is the connection of the automatic antenna very important. Even if it has this designation, the connection of the automatic antenna is meant for much more.

When the car radio is switched on, the 12 V plus pole is released to this connection and can thus switch on all the additional devices connected to it. This eliminates the need to manually turn on the CD changer, amplifier, or powered speakers.

handsfree car connectors

ISO car radio connector block A: responsible for power supply

3.1. ISO car radio connector block A (power supply)

Pin 1: speed signal – a pulsating speedometer signal for navigation systems
pin 2: phone mute
pin 3: not used
pin 4: + 12 volt – permanent plus for memory retention (terminal 30)
pin 5: + 12 volt – output to control z. B. From car power amplifiers or antenna amplifiers
pin 6: radio light
pin 7: + 12 volt – switched plus via ignition socket (terminal 15)
pin 8: – ground from vehicle chassis


ISO car radio connector block B: the speaker connector

3.2. ISO car radio connector block B (loudspeaker)

Pin 1: loudspeaker + right rear
pin 2: loudspeaker – right rear
pin 3: speaker + right front
pin 4: loudspeaker – right front
pin 5: speaker + left front
pin 6: speaker – left front
pin 7: loudspeaker + left rear
pin 8: speaker – left rear

handsfree car radio connectors-3

ISO car radio connector block C: the preamplifier

3.3. ISO car radio connector block C (preamplifier)

pin 1: TXD connector
pin 2: rxd connector
pin 3: + A CD changer
pin 4: + U CD changer
pin 5: ground pin 6: ground
pin 7: output preamplifier right front
pin 8: output preamplifier right rear
pin 9: output preamplifier left front
pin 10: output preamp left rear

3.4. Adapter for the ISO connector

Most radios today use standardized ISO connectors for inputs and outputs. However, there are also a few manufacturers who use their own connector system. For this purpose, there are vehicle-specific adapters which adapt the pin assignment to an iso connector.

  • car radio adapter on amazon.View De "

3.5. phantom power

Many car radios have a active antenna output, which feeds the amplifier the antenna feeds. If a device does not have this, the result can be poor radio reception. The solution is a so-called phantom power – a power supply adapter – which is connected between the radio and the antenna and supplies 12 volts to the antenna amplifier.

handsfree car kit installation

driving a car with a cell phone attached to your ear is not only dangerous, but also forbidden for a long time now. A hands-free system solves the problem.

4. install handsfree kit

Since 2001, telephoning in motor vehicles is prohibited according to § 23 abs. 1a stvo (D) expressly prohibited and only permitted with a hands-free system. Failure to do so will result in a fine of 100 euro charged and you get a point in flensburg.

The handsfree car kit allows the car driver to use the phone calls in the car without having to hold the phone in your hand. The systems have powerful microphones and a loudspeaker for voice output. However, a distinction is generally made between permanently installed hands-free systems and "plug’n play" hands-free systems.

hands-free car cigarette lighter

A hands-free kit for the cigarettes lighter can be connected to the smartphone via bluetooth.

4.1. Handsfree as a plug’n play solution

With a plug’n play solution, it is a small mobile handsfree device that can be easily installed in the vehicle.

There are different variants, like e.g.B. Handsfree devices that are plugged into the cigarette lighter, or wireless solutions for the sun visor.

loudspeaker and microphone are mostly integrated in these devices. Operation is usually via the device itself or via the cell phone, which is often connected to the hands-free system via bluetooth.

Here the advantages and disadvantages the plug’n play variant in the overview:

  • High mobility
  • No conversions necessary
  • Low cost
  • Requires external power supply
  • Modest voice reproduction
  • Uncomfortable operation

4.2. Fixed installation solutions for handsfree car kits


nowadays many cars have a fixed installed handsfree in the dashboard.

In the case of the fixed installation solution, it is a permanently installed hands-free device, which permanently paired with the car radio is and has a constant power supply. there are handsfree devices, which are already integrated in the car radio, but most of them are only coupled and have their own display and control unit. often, additional steering wheel remote controls are installed to make operation even more comfortable.

When it comes to cell phone connectivity, there are cradle-mounted and cradle-less solutions, with the trend moving toward cradle-less solutions, which are mostly implemented via bluetooth.

Some handsfree kits have an additional slot for a second SIM card, which also allows you to make calls without a cell phone.

  • High comfort
  • Very good voice reproduction
  • Many additional functions
  • Higher price at purchase& installation
  • No flexibility

5. The installation of a hands-free car kit

Installing a fixed hands-free car kit

Many manufacturers now offer solutions, working with ISO adapters.These adapters allow the handsfree to be paired with the car radio and speaker system.

For the installation you should tools like screwdriver, needle nose pliers and side cutter be ready. Depending on the type of vehicle, of course, the conversion can take different forms.

First disconnecting the car battery at the front of the engine compartment, to avoid possible damage during installation.

Now you should remove the car radio to get to the ISO connectors there. Once you have found the connections, you can disconnect the plug and connect the hands-free adapter between them. On the adapter itself, there are cables with a plug to connect to the hands-free car kit. For the installation of the handsfree kit you should use choose a safe place, like the glove compartment.

Once the control unit is wired to the car radio and the speakers, you can with the display and the microphone continue. These should also be attached in a suitable position so that they are clearly visible or visible from the outside. Are optimally aligned.

After all components are connected, the car battery can now be connected to perform a functional test. If the hands-free system works as desired, the car radio can be re-installed and the installation is complete!

  • Handsfree car kits on amazon.View "

photo credits: adobe.Stock/daviles, adobe.stock/weerawat, adobe.stock/dmitriy, adobe.Stock/dmitriy, amazon/PATISZON adobe.Stock/f8studio (chronological resp. Sorted according to the order of the pictures used in the buyer’s guide)

As a skilled craftsman with a passion for writing, i have turned my hobby into my profession. Now I write as a freelance editor test reports and guides around the topic of home improvement.

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Christina Cherry
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