Free high quality hard-wired iPod/mp3/iPhone/etc.

Post by **fazool** » 17 Mar 2012, 18:40

I found an old thread about patching in to piggyback on the tape signal lines of an 850's head unit. I believe it was an HU-813.

Instead of using a cassette adaptor (which degrades the audio signal) and instead of tapping into the CD-Changer inputs (which costs over $100), the idea was to solder a stereo jack into the lines that send pre-amp signals out from the tape head and which feed into the on-board amplifier. In this way, you can connect using an iPod or MP3 player headphone output and it will go cleaninly into the on-board amp, bypassing the tape adaptor and magnetic tape head.

If you have an old set of headphones, this is a free modification. You can place a panel mount femail 3.5mm jack somewhere convenient (there is plenty of room on the stereo faceplate or just snake a male cable out through the cupholder.

I couldn't find a recent write-up for this so did mine with some trial and error. Here are my notes and some photo's on doing this on a more recent system. Mine was an HU-615 in a 2001 S60.

Preparations:
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Disconnect your negative battery terminal and wait 5 minutes before commencing any work. I got lazy and was doing a quickie change and forgot to disconnect. That gave me a dealer-only-clearable airbag light and $110 bill. So, learn from that mistake - disconnecting the CCM will trigger an SRS fault, so you must disconnect your battery.

Removing the head unit:
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This is well described in many places, so I won't repeat it in detail. The pen-holder and shroud around the shifter pops out by hand. Two large Torx screws release the CCM (Climate Control Module). Pull the CCM straight out to snap out of the spring clips between the CCM and the HU.

Two large Torx screws hold the bottom of the HU in. Remove these and pull the HU out from the dash. Disconnect the green and grey wire harness plugs and the antenna plug and take the HU out of the car.

Disassembling the Head Unit
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The Head Unit is very modular. The CD player and tape player are self-contained modular units. These connect to the main unit and amp through flex-circuit connectors.

A large cast aluminum bracket is bolted to the HU assembly. Remove this by removing the five Torx screws and sliding it off the back of the unit. Unsnap the cup holder.

The top cover of the HU can be removed, like opening the lid on a box.

On this model (unlike the HU-813) the CD player is on top and the tape player below. The cd player is connected in the back with two screws. The CD player is connected in the front with two screws that screw into a separate mounting bracket, which also has two screws. The easiest method is to remove the two screws accessible through the clearance holes. If you remove the other two screws, you are actually loosening the whole mounting bracket, which isn't necessary.

In the back is a press in flex circuit. Gently pull straight up to remove this.

See the first picture, showing the system with the CD removed. Looking down you see the tape unit. On the right side is a printed circuit board. This is what you are after.

To remove this board, you need to gently twist the bent metal tab on the side. The back side has a connector on the underside which you cannot see, but it plugs into the board in the back of the system. So, to remove this board, you will free it from the metal tabs and lift from the front side, tipping it up. There is also a flex cable that plugs into a connector on the
underside.

Lift the front side of this board. Pull up gently to remove the flex connector. Pull up and toward the front to unplug the rear connector. It looks worrisome when you see it the first time but its rather easy to remove and reconnect once you do it.

Modifying the PC Board
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Route your cable into the HU chassis.

3.5mm stereo cables are pinned out with left+ at the tip, right+ at the middle and shared ground as the last connector. Tone or ring out your connector so you know which is right and left.

On the PC board you just removed are two trim pots (signal level adjustment potentiometers) - one for each channel.

In the photos below you can see the solder points for these two pots. You need to solder the left+ and right + wires to the center/wiper terminals of the pots (marked with "W" in the photo). A stereo jack/plug shares ground signals so you only need to connect one of you ground wires (they are coupled at the plug end already).

Reassembling
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Reverse the above steps. Use caution reconnecting flex circuits and don't crease them or you can crack the traces.

Cassette Insert
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To fool the tape player you need a fake cassette tape. The tape player can detect a broken tape so you may need a cassette adaptor, but with the wire cut off - this way it fools the deck but doesnt deliver a signal. I tried an empty cassette case and a modified casstte case - the deck kept popping them out and wasn't fooled.

Post by **fazool** » 17 Mar 2012, 18:41

This mod allows the tape player to still work and a direct input into the amp from your iPod/mp3 player. The signal quality is excellent.

Post by **Fish stick88** » 17 Mar 2012, 21:50

Well done! Very nice fix!

PDLarson · Post by **PDLarson** » 18 May 2012, 17:32

Awesome fazool! I saw a similar mod here http://tutorials.newcougar.org/HowToMP3 ... kRadio.pdf and always wanted to do it to that car but never did. Luckily my Volvo came with an iPod adapter or I would have been looking to do exactly what you did but to a 816 or 910. Well done.

1998 s70 · Post by **1998 s70** » 28 May 2012, 09:58

Man this is awesome,
I'm doing this today if my HU is also an 816. I've been wanting to get an adapter for at least the last six months but have been waiting until I get my S70 completely sound mechanically. Now there is almost no cost. Just a cheap fake tape and my old headphones. Thanks again and I'll let you guys know how it comes out.

Reboot · Post by **Reboot** » 30 May 2012, 20:17

Nicely done! I've been wanting to do this for a while, now I don't have any more excuses for putting it off. I especially like the idea of using a female connector and making it look factory.

Post by **Jack Rock** » 31 May 2012, 11:43

Just a word of caution; the tape player does need to be functional for this to work. The tape system, like all other tape decks, needs to 'see' proper tension on the tape reels so I don't think gutting an old tape will work but a tape adapter should. There is also a sensor for tape tension which tells the deck the tape is over and to auto flip to the other side. I tried this on one deck I have and the HU kept switching from side A to side B over and over and produced no sound. I tried on another deck I have that had no tape drive belt, same result. I've also run into a problem where one tape adapter brand worked but another did not, just kept spitting it out. But, for zero cost, give it a shot.

coldax · Post by **coldax** » 12 Jun 2012, 13:45

I have a DICE module installed in my Toyota and I can't imagine owning a car without it. MyPodCarKit.com hooked me up with a cradle too so I can keep my precious iPod within reach for one-handed docking. My recommendation? Don't delay and start enjoying crisp clean CD quality music with constant charging, stereo head unit control, album/artist stereo text display and steering wheel control, ALL from your factory stereo. Just imagine having access to over 10,000 MP3s at the touch of a button!

The best iPod & iPhone Vehicle Integration Source I've found!

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Post by **matthew1** » 12 Jun 2012, 14:04

^^^ He was a spammer. Account deleted, posts removed, IP banned.

Brett · Post by **Brett** » 07 Aug 2012, 12:56

Just wanted to say thanks and that this was a great post.

Without any real hardship I pulled this off in my 99 S70 and my wifes 98 S70 in under an hour, what a savings compared to the alternate ways to get an AUX. The two head units I had were both different from the one in your description and as such I could not find the tape player tap in, but easily found the CD tap in on both units. The sound is crisp and the only complaint I have is the low volume, but I am chalking that up to the weak pre amps in ipods. Going to go back and swap out the male connections I put in for female connections to go for a cleaner look and will post a couple pics for reference in case people need help with other head units.