Leaf S - replacing the radio?

[carStereo]

referring to the same post: http://www.mynissanleaf.com/viewtopic.php?f=36&t=26210

The build microphone can be used for OEM stereos with a little adapter. The 2011-2017 Leaf uses a Mic Amp that amplifies the microphone signal and adds about 2 V DC to the signal as documented in the manuals found at nicoclub.com. OEM Stereos require an un-amplified signal without DC component. The little adapter uses a capacitor to filter out the DC component and then a resistance divider to lower the mic signal. I have used that circuit in a 2016 Leaf with both Sony and Pioneer Radios and it works well. You need to make sure to provide 5V to the original Mic Amplifier, which you can either take from a USB output of the OEM Stereo or any USB adapter.



The 2015 and earlier models provide 5V from the original BT module, which can be reused as mentioned at http://www.mynissanleaf.com/viewtopic.php?f=36&t=23887. The 2016 and 2017 models do not provide 5V other than from the original Stereo. Unfortunately, I do NOT know if the 2018 and later models still use the same amplifier.

[lukep]

Does anyone have experience with the head unit in the 2019 S? I have a base S, which has a stereo in it that looks like this:



On eBay I've seen a 19/20 OEM head unit that I'd like to replace it with. It looks like this:



The head unit in my car apparently has a 32 pin connector while the new head unit would have a 40 pin connector, so I'm wondering what the options might be.

[ncoig]

referring to the same post: http://www.mynissanleaf.com/viewtopic.php?f=36&t=26210

The build microphone can be used for OEM stereos with a little adapter.

This is a brilliant solution, but I'm not brilliant enough to divine where this is supposed to happen based on pin numbers --- is this fix performed at the rear of the head unit, or at the BCM in the trunk? I'm trying to visualize where I'm supposed to splice in these components.

Any help would be much appreciated.


-N

[ncoig]

This is a brilliant solution, but I'm not brilliant enough to divine where this is supposed to happen based on pin numbers --- is this fix performed at the rear of the head unit, or at the BCM in the trunk? I'm trying to visualize where I'm supposed to splice in these components.

... and to clarify, I've stared at the wiring diagrams (I have a 2013) and it would appear that the mic terminal pins are not the 37/38/39 (which are indicated to be in the harness) that "carstereo" posted... the service manual states Connector M84 [AUDIO UNIT] contains terminal

24/R - Tel Voice -
25/G - Tel Voice +
26/Shield - Tel Voice Ground

-N

[carStereo]

I used the mic adapter in a 2016 Leaf. Everything was easily accessible directly behind the head unit. The pins refer to the big connector going directly into the head unit. I never had to do anything in the trunk - thankfully

chumpp describes at https://www.mynissanleaf.com/viewtopic.php?f=36&t=23887 in all detail how to handle the 2013 -2015 Leaf, where the BT component is in the trunk - unfortunately. He suggests to "CHECK MY PIN NUMBERS FROM THE SERVICE MANUALS (2014 LEAF & 2015 SENTRA - select "AV" ". Nicoclub has those manuals. In essence you need to bypass the BT component in the trunk and use the existing wires to get the mic signal to a new headunit (which already contains its own BT module). For the 2013-2015 models, It may be a lot easier to just use the mic provided by a new headunit instead of dealing with the trunk ...

[ncoig]

I used the mic adapter in a 2016 Leaf. Everything was easily accessible directly behind the head unit. The pins refer to the big connector going directly into the head unit. I never had to do anything in the trunk - thankfully

chumpp describes at https://www.mynissanleaf.com/viewtopic.php?f=36&t=23887 in all detail how to handle the 2013 -2015 Leaf, where the BT component is in the trunk - unfortunately. He suggests to "CHECK MY PIN NUMBERS FROM THE SERVICE MANUALS (2014 LEAF & 2015 SENTRA - select "AV" ". Nicoclub has those manuals. In essence you need to bypass the BT component in the trunk and use the existing wires to get the mic signal to a new headunit (which already contains its own BT module). For the 2013-2015 models, It may be a lot easier to just use the mic provided by a new headunit instead of dealing with the trunk ...

Thanks so much for replying!

OK, the picture is getting clearer - so the terminals I see of 24 and 25 that I see in my 2013 schematic must be the "old" wires chumpp refers to. I can just pin those on the harness and connect them to the mic jack - so long as I can route +5 to the trunk and put it to pin 29.

I bought a steering wheel BT button harness, so I should be able to pin those easily, too. Just need to find +5 somewhere.

Can you tell me, though, why all the 1 microfarad caps I see are 50V and not 16?

-N

[carStereo]

50V will be fine. It is the maximum voltage rating that the capacitor can handle.

[ncoig]

50V will be fine. It is the maximum voltage rating that the capacitor can handle.

OK, so I'm at a loss. I followed (I think) your schematic, but all I get is HISS from the mic with a little bit of garbled garbage in the background, so I assume I have a hot mic.

Just to be clear, the capacitor goes positive leg first from the mic, then to the 100kohm resistor on to the TIP of the plug, then bridging the 2.7kohm after the 100kohm across to the RING terminal?

The third wire is just to feed the 5V, which I'm doing from the trunk, so I should only have two wires hooked up behind the radio, yes?

I think I'm puzzling over the "Shield" terminology, which I am to understand is a ground from the mic, which is not grounded on its own at the mounting point.

Thanks!

-N

[carStereo]

Unfortunately, I'm not familiar with the meaning of the "RING" terminal. The 2.7k ohms resistor should bridge to ground/shield. The two resistors function as a voltage divider to lower the amplified Mic signal of the Leaf to work on a highly sensitive Mic input of an after market head unit. 2.7kohms/102.7k is just about 2.5% of the input voltage or a reduction of almost 40db. Choosing a resistor grater than 2.7k ohms will INCREASE the volume, while choosing a smaller resistor will further decrease the volume.

A few more things to consider:
1. I'm not sure if the 2013 Leaf actually amplifies the MIC signal. The voltage divider is only needed if the mic signal is actually being amplified.
2. Please check the input sensitivity of the mic input on your replacement head unit. Most after market units expect a raw mic signal without amplification. If the car amplifies the mic signal, the voltage divider will reduce it back to what the after marked head unit can handle without signal distortion. However, if you use another NISSAN head unit, it may actually expect an amplified mic signal. In such a case, there is no need to divide the mic signal at all.
3. The capacitor is used to "eliminate" any DC voltage on the mic signal wire. Polarity depends on the DC voltage on the mic signal wire. In the 2016 Leaf, that voltage is POSITIVE, which is why the + side of the capacitor is connected to the mic signal wire.

[ncoig]

50V will be fine. It is the maximum voltage rating that the capacitor can handle.

OK, so I'm at a loss. I followed (I think) your schematic, but all I get is HISS from the mic with a little bit of garbled garbage in the background, so I assume I have a hot mic.

Just to be clear, the capacitor goes positive leg first from the mic, then to the 100kohm resistor on to the TIP of the plug, then bridging the 2.7kohm after the 100kohm across to the RING terminal?

The third wire is just to feed the 5V, which I'm doing from the trunk, so I should only have two wires hooked up behind the radio, yes?

I think I'm puzzling over the "Shield" terminology, which I am to understand is a ground from the mic, which is not grounded on its own at the mounting point.

...answered my own question...sort of... so I took the contraption out of the line and hooked the mic straight to the radio. Still garbled. Then I switched the pins. Worked like a charm with no caps or resistors.

Unsure what the deal is, but since it works, I'm happy.

-N