Stereo and GROM BT3 troubleshooting

[bstone2026]

Recently purchased a 97 (from a member on here that posted it here. Love the car!) and and having trouble getting the GROM BT3 to work.

Forgive me if this has been posted before, I tried to search and didn't see anything specific.

recently purchased the GROM BT3 and after trying to install it behind the driver seat, I couldn't get the CD changer cord to unplug. It was mega stuck...
So, just to test it, I tried to just plug it in the trunk with the cord where the CD changer ( I assume) used to be.

After turning the car on GROM doesn't show on my available bluetooth options on my phone, and the stereo wont change to cd disc 1/track 1

So here is my question. Did all NSX stereos have cd changer capability? My stereo button only has Am/FM button, no CD option.


I have seen pictures that show the stereo with a CD label on that button...
But then again i have seen pictures with no cd label on that button but the display shows CD disc1/track1


Other thoughts are the cd changer cord very well may be unplugged from the back on the stereo. Was hoping to avoid taking apart the dash and unplugging the stereo bc i am not sure i have the factory code....

Any thoughts?

 

[Wild Turkey]

I believe the GROM works with 1991-2005; it definitely worked with both my 1995 & my 01, and the stereo didn't change, so your 1997 should work. My 1995 stereo also had no mention of CD on the AM/FM button but you just press it one more time and CD comes up. Check your owner's manual. The question of whether it comes up if you don't have a CD changer or a GROM hooked up is a good question though. It would make sense for the head unit to skip back to AM if there is no changer (or GROM) installed. I thought I remembered that it still had an option for CD when I pulled my changer before I got my GROM, but now I'm seriously questioning that.

Probably the only way to know for sure if is connected at the back of the head unit is to pull it out and see. That said, a wiring diagram for the pins would let you test the 12 V lead in the trunk. Even without a wiring diagram you could just test for voltage at all of the pins. One should have 12 V with the stereo turned on, which would confirm it's plugged into the back of the head unit? It's also possible something else has been plugged into the port in the back of the head unit by a previous owner. A couple companies made some iphone adapters back in the day and I found one while trying to trace odd-looking wiring.

Personally, I think behind the head unit is the best spot for the GROM anyway, but yemv. (Follow the Prime instructions for removing the console without damaging it!) The GROM sits nicely and can be wedged in with a couple of pieces of foam. It also allows you to run a USB power to the glove box very easily. I'll be adding the NSXPO wireless charger they included with the NSXPO swag this year to my glove box shortly.

Thread 'DIY: Shift Boot Change (Center Console Removal) (91-05)'

29 January 2024

In this video I'll show you how to remove and replace your 1991-05 Acura/Honda NSX Center Console. Whether you need to remove it to replace your shift boot like we did here, or you need to access your radio, climate control or shifter, there are a lot of reasons to need to know how to remove it. I'll also show you how to handle it carefully so you don't damage this costly part.

0:00 - Introduction
0:26 - Remove Storage Compartment
1:40 - Clock Removal
2:20 - Vent Removal
2:55 - Console Removal
4:48 - Shift Boot Installation
5:59 - Console Installation
7:28 - Vent Installation
8:02 - Clock...

• Chris_Lum
• Replies: 1
• Forum: DIY Videos

Post in thread 'CCU removal/repair'

17 December 2023

Several thousand dollars? Purchase my plane tickets and I will come and remove it for you for less.

As long as you are not ham-fisted, removal of the CCU is not difficult. In the NSX Prime Library (link in top red banner) you will find a link to the 1991 service manual and page 22-84 in the service manual details removal of the CCU. The most difficult part in terms of the risk of damage is removal of the clock from the center vent and then removal of the center vent assembly from the center console. Note the location of the retainer clips for the clock and the vent shown circled...

• Old Guy

• 

Lastly, are you sure the GROM is good? Someone posted in the past about a dud GROM. After a ton of work trying to get it to work, GROM finally sent him another one that worked perfectly. I can't find that thread though.

 

[TANTO]

Ditto Wild Turkey- my 92 came with the CD (dealer installed i suspect) and all was well with it, but as mentioned it works without no dedicated button needed on the radio. Way back i added the GROM for an I-pod and it also seemed fine. I had my unit behind the drivers seat panel FWIW. I would be really surprised if your cable was not plugged into the OE radio from the factory. I "think" the CD wiring (and perhaps even phone) was installed in all the cars as i recently stripped it all out just for simplicity when deleting my whole system and the cabling did not appear dealer installed. I have a pristine OE CD unit for sale (had to add that he-he - see adds). I can send you my old GROM unit for free is that would help, but it is likely many versions old - bluewhat he-he?

 

[Heineken]

The GROM works as a replacement for the CD changer. Switching to CD/GROM is done by pressing the tuning button until the display changes to CD mode.

Since it's a two way communication bus on the CD changer port, the switch to CD mode only happens if a working CD changer or GROM is attached to the radio.

 

[bstone2026]

Couple of updates. Appreciate everyones input.

I think the cable may not be plugged in in the back of the headunit.

I happen to have an old cd changer from my 95 prelude vtec that I pulled out of storage. It definitely worked when I took it out of the car 20 + years ago



Nothing. Didn't get any response from the cd changer or the headunit.
So... I then went and found the original window sticker and it appears my car was pre-wired?

Which leads me to believe the cord in the back of the headunit may not be plugged in...
I really didnt want to pull apart the dash, but it appears i might have to.

Finding the old cd changer was a huge PITA... Pulled out like 15 storage bins before i found it... Good thing i never throw anyting like that away

Any thoughts?

 

[MJK]

From memory, the HU to CD changer communication is via Alpine MBus protocol. So, any MBus changer should work.

I also recall using an Mbus to Ainet adapter early in my ownership when I wanted to play MP3 encoded CDs with an Alpine S634. So, I believe an Ainet changer can be made to work with something like a KCA130B adapter.

 

[Wild Turkey]

The were all "pre-wired" with that DIN cable from the factory, which has a joint behind the driver's seat that seems to be fused in your case. I think all of the CD players were dealer add-ons, which is why you see them in all different locations.

Did you check for voltage on any of the pins at the trunk end? Probably moot; it sounds like you need to access it in the dash to check. It really isn't that bad - you already spent more time finding your old CD changer that pulling the radio would be. Just take your time, & use credit cards under the vent clips when you pull the vent.

Also, you can now install the GROM behind the dash, where it will have easier communication than to a GROM unit in the trunk.

 

[Kaz-kzukNA1]

No longer have access to BT3 so following info could be outdated or wrong.

Looked into BT3 and communicated with GROM few times regarding the problem when connected to the European spec audio head unit;
https://www.nsxprime.com/threads/gr...with-european-spec-oem-head-unit-only.221334/


Based on what you wrote so far, most likely, you are not getting any power at the DIN connector located at the right side of the trunk/boot.

Can’t remember whether the BT3 uses the permanent +VB or ACC only so you may need putting the IGSW into P1 ACC for the following testing procedure.
Also, you ‘may’ need powering up the audio head unit by pressing the On/Off switch as well.

1. Disconnect the BT3 unit from the cable and pop open the bottom lid.
Very easy to do so.


2. On the circuit board, you should have LED module.
Depending on the revision/version of the circuit board, may look different but on this one, I think it was at the D5.

3. Re-connect the GROM cable to the BT3.
The LED should turn red if getting any power.

4. If not, check the following.

5. From the back of the audio head unit to the right side of the trunk, there are few DIN connector breakouts/connections.

6. You’ve already touched on the one behind the L-side seat.
On earlier models, you will see 2 x DIN connectors.

8pin DIN for the CD changer and the other one (13pin??) for the optional phone kit.

7. Another connection at the Left Forward section of the trunk behind the carpet.
Again, 2 x DIN connector.
Check the one with 8pin.

The 8pin DIN should be connected to the CD changer extension cable that leads to the right side of the trunk as in your photo.

On some NSX, this 8pin connector was disconnected.

Also, you may have some sort of aftermarket device connected/sandwiched there to share the MBUS signal.
I don't know the detail but I think there used to be the I/F that prevented the power antenna from operating when in CD mode.
Since GROM, USA SPEC PA11-HON (discontinued), etc are CD changer emulator, should work fine even with such device connected but may want it removed for the testing purpose.

8. If you have the multimeter, you can check the +VB and ACC power at each breakout points.
There used to be pinout diagram in Wiki or somewhere on this site but couldn’t find it.

9. Compared to the aftermarket Alpine CD changer with MBUS DIN connector, Honda/Acura branded units use different pinout.
It swapped the pinout between the R-ch and the SGnd but kept the PGnd, +VB and ACC at the same position.

So, just search for the ‘Alpine CD changer DIN pinout’ on the web.
Lots of images available.

10. Quite surprised that you couldn’t disconnect the breakout behind the L-side seat.


If you can check the power supply at the breakout point using either the BT3 LED method or the multimeter, then that should tell whether you need to remove the centre console or not.

I prefer installing the GROM device behind the seat.

Kaz