krue92

I have a new Dice unit that was installed with the R4 cable so I could keep my XM. In Ipod mode the unit sounds great, but when I switch to XM Mode, I get engine noise. The shop that I bought it from has tried two different cables and two different Dice units. If I have my XM hooked up the way it is hooked up stock, I have no issues. The shop and I are both frustrated and I am about to just give up on Dice. Has anybody else had this problem.

Thanks,
Kevin

csmeance

Make sure that all connections are firmly inserted. Also make sure that none of the pins in the radio, Factory XM harness and dice harnesses are straight and not bent.

krue92

I double checked that on both cables and both Dice units. They all look fine and I get the same results on each of them.

Nick@DICE

Bad harness. Send me your contact and mailing info to nick@diceelectronics.com and I'll send you another.

krue92

I just received a new harness from your company and it is still doing the same thing. Like I said I have tried 2 new harnesses and 2 new Dice modules. Another thing I have noticed is that my XM gets noticeable quieter when I have the Dice module plugged into the harness. I thought this was kind of odd.

Nick@DICE

They're BOTH doing it???

Ok, that's odd. bent pin on the radio side?

krue92

I checked that and everything is in tact. When I have the stock harness plugged into the head unit XM works fine. The Dice harness works fine until I hook the Dice module up, then I get engine noise and the XM gets noticeable quieter.

Nick@DICE

I'm not so worried about the quieter part. If you flip through the sources it will auto-adjust. I'm more worried about the road-noise/alternator noise.

krue92

The shop I am dealing with is working with your company now and they are shipping us out a whole new unit with cable and module. Hopefully we will have better results.

krue92

The shop I am dealing with is working with your company now and they are shipping us out a whole new unit with cable and module. Hopefully we will have better results.

drat19

Nick@Dice: I also have the "XM gets noticeably quieter issue", but only occasionally. When it happens, I simply flip my source over to Tape/Disc, then back to XM, and the normal volume is restored. This is an annoying problem (happens maybe once every few days), but not enough to have me bring the car back in and have my dealer (who I paid to do the work for me) re-open my dash for a "maybe" solution.

Any thoughts, though, on why this intermittent problem?

Nick@DICE

It's the car, it's just learning the line level so it doesn't blow out your ears or the speakers. If it happens every few days my first guess would be a loose wire or a weak battery in the car.

drat19

Appreciate the response, as always.

I don't think it's a loose wire as the "solution" (read: workaround) I have is reliable...input source flip/back always resolves. Weak battery is an interesting theory...can you elaborate on what you're thinking on that?

Nick@DICE

A weak battery can make the computer do weird things. We've seen similar things happen.

If you want, we can swap everything out and see what happens.

drat19

Appreciate the offer on that. Issue is that I am not comfortable taking apart my dash (tried it once and that's why I ended up bringing it to my dealer to do it; I bailed halfway into the job when I wasn't comfortable I'd be able to "put humpty-dumpty back together again"), and I know my dealer will charge me to take it apart again; not to mention the fact that he's 60 miles away from me in Mobile (I'm in Biloxi).

I will continue to monitor to frequency of the occurrence and will then decide how much of an inconvenience this turns out to be.

Continued thanks....

gatrhumpy

iTrader: (1)

I had a similar problem on my Accord with the Blitzasafe adapter. It would not go away. I finally uninstalled it and XM came back crystal clear again.

Nick@DICE

That was definitely a bad harness.

krue92

Well my shop received the new module and cable and we had the same engine noise problem. We tried a bunch of things the tech told us to do, but had no luck. I am just going to have them send it back and we are going to try a different brand of Ipod interface. Thanks for trying to help.

ffej

I had what sounds like exactly this problem in my TL a few months ago. I ended up making a tiny modification to the DICE module, which solved my problem completely. It was a tiny modification, but the road to it was long and torturous. I'll give a condensed account of the journey here in the hope it can help krue92 or anyone else with this problem. (At least I'll condense it enough to leave out all the really dumb things I tried that didn't work.)

In my case the engine noise on XM was noticeable at volume levels above 20 or so (out of a max of 40). With very quiet program material -- which seems to happen on the classical channels (e.g., 110) more than anywhere else -- I sometimes turn up the volume up to 30 or 35. When I would do that with the unmodified DICE module, the engine noise would drive me nuts.

I would also experience a significant drop in XM volume after disconnecting and reconnecting the DICE module. Of course that would just cause me to turn up the volume, which would increase the engine noise level, which would drive me nuts.

Like krue92, I got a replacement module from DICE, but the new module behaved identically. DICE suggested trying a new harness, but I was skeptical that that would solve the problem, as I had checked the harness myself more than once for bent pins, continuity, wire kinks, and so on. Still, it was worth a try, because I really liked the DICE module otherwise and didn't want to give it up.

After what by now had been three or four weeks of driving around with my center console splayed to its bones, I spoke by phone to Nick at DICE (presumably the famous Nick@DICE of these pages, but for some reason I didn't make the connection at the time). Since I'm in the LA area, he suggested I drop by their place near the Long Beach airport, so I took him up on it. Nick graciously explained that I really didn't want to be disconnecting and reconnecting the DICE module while the ignition was turned on, and he showed me that if I would simply turn the key to off and then on after reconnecting the DICE module, the XM volume would be restored to normal. Then he brought out a new harness and a guy who obviously had much better fingers than mine, as he managed to reconnect the harness to the back of the headunit in only a few seconds, something that took me 10 to 20 minutes with my head under the steering wheel and my ankles wrapped around the headrest every bloody time I did it.

With the new harness in place, we tuned around to a few XM channels, including the classical ones, and heard no engine noise, so it seemed like the problem was solved. I thanked Nick and left.

But the problem wasn’t solved. Apparently the program material on all the channels we tried just happened to be loud enough that the engine noise was masked. Because minutes later, on my way back, I found some much quieter music, and along with it the familiar engine noise. It drove me nuts.

Nick told me he hadn’t heard of noise problems in TLs like the one I described (but that he never actually heard in my car). I figured maybe I was just “lucky” enough to have a rare electrically noisy TL. Clearly the engine noise was somehow getting coupled into the audio system through the DICE module and/or its wiring harness. Since I used to do some electronics in my distant youth, I decided to see what I could do about the noise coupling myself.

First, I borrowed a good oscilloscope and looked at the +12 V line of my TL. With the engine running, there were clear, sharp spikes about 300 mV high at the spark plug firing frequency (e.g., 40 Hz for 800 RPM). Nice. Each spike had a very narrow major peak a few microseconds wide followed by a much wider “shoulder” of maybe a few hundred microseconds. I don’t remember exactly. But do I remember enough from my EE days to know that this kind of noise is a pain to filter out using standard passive components like choke coils and capacitors. Still, that’s exactly what I tried. But I failed.

After giving up on simple filtering, I decided I needed to know more about the DICE module’s audio output circuit. Here I needed to borrow a dissecting microscope so I could see the tiny parts and traces on the tiny circuit board. I found the following:

1. The left and right audio output lines are accompanied by an audio return line that is separate from the power return line. This is good, as it provides a means of isolating the audio circuit from from any noise on the power return.
2. The audio output lines (left, right, and return) are connected in parallel with the XM unit’s audio output lines. That is, both sets of lines feed the headunit through the same input lines. But they are connected to the DICE module’s internal circuitry through three CMOS analog switches, which are basically solid-state versions of relays. This is good, since the analog switches can be “opened” to isolate the module from the headunit when XM is in use. Presumably the XM unit has a similar arrangement, so only one of the two sources (XM or DICE) “talks” to the headunit at a time. Remember, I’m talking about the configuration with the R4 harness, where the XM and DICE units are “Y-ed” together.
3. Within the DICE unit, the audio return line is connected to the power return line through a 100 ohm resistor. This is not so good. It compromises the isolation that a separate audio return provides by coupling some power return noise (“ground noise”) into the headunit’s audio input. I’m sure the designers had a reason for adding this resistor, but without knowing anything about the XM and headunit circuitry, I can only speculate about it. At least in my configuration (R4 harness, XM always connected) it’s not doing anything good. What it’s doing is causing a weak ground loop.

So the tiny modification that solved my noise problem was simply to disconnect the 100 ohm resistor between the two return lines. Now the engine noise is gone, and I’m no longer being driven nuts.

If anyone else has this problem and has reached the warranty-be-damned breaking point, they can try removing the offending resistor as follows. (At least this will work if their module is of the same version as mine.) First, disconnect the DICE module from the car cable harness. Next, remove the plastic module cover by squeezing at the four indentations around its periphery, then locate the connector that the car cable harness connects to. It’s on one of two small circuit boards, which lift out easily once the cover is off. Now look for a tiny rectangular block roughly a millimeter across off to the left of the car connector as you’re looking into the connector from the outside, where the harness goes in. This is the problem resistor. It has two metallized ends connected to very fine circuit board traces. Mine was black, with “01d” printed on it in microscopic type -- this just means 100 ohms in secret resistor code. Now you can either carefully unsolder the resistor if you have a fine-pointed soldering iron (everything is tiny – don’t make a mess), or else you get an X-acto or other sharp knife and carefully cut one of the tiny circuit board traces connected to the resistor. Either way, the operation is reversible with a fine-pointed soldering iron and a steady hand.

By the way, item number 2 in the list above explains why the XM audio level sometimes drops noticeably when the DICE unit is reconnected. Apparently when the DICE module is plugged in when the XM receiver and the headunit are already on, it doesn’t get initializated properly, and it “closes” its analog switches, so that it tries to drive the headunit simultaneously with the XM receiver. Since the iPod isn’t actually outputting anything at this time, you only hear the XM signal, but it’s reduced in amplitude as the DICE unit “fights” with it, trying as hard as it can to output a zero signal.

One more thing. I also experience occasional spontaneous drops in the XM signal level as reported by drat19. I ascribe these drops to the DICE module’s occasionally closing its analog switches, perhaps due to those nasty noise spikes on my 12 V line. Like drat19, I just switch over to the DICE module (Tape/Disc) and back to XM, which restores the XM volume. I assume the switch back to XM tells the DICE module its output is no longer wanted, so it “disconnects” by opening its analog switches.

drat19

Thanks, ffej, for the amazing engineering-oriented discussion points.

Nick@DICE

My brain hurts. I gotta print this out and let it soak in.

ffej

Sorry about that. I started out intending to be brief, but I guess I got a teensy bit carried away.

Nick@DICE

Pfft, don't worry about it. Knowledge is power and I'll be giving your findings to the engineers for review.

krue92

Thanks so much ffej. My shop and I decided to try that and sure enough it got rid of the engine noise. I'm not sure what that resistor was for, but my car sounds great now.

krue92

I think I may of found out what the resistor is for. Now when I shut my car off, if I am in Ipod mode, it doesn't pause. If I change the audio to a different mode with the car on, it does pause. Maybe that little resistor is what let the Ipod know that the car was off. Either way, I would rather have it this way than have the noise I experienced with my XM.

ffej

That resistor is purely part of the audio output circuit. The DICE module's control circuitry couldn't care less whether it's there or not. So I don't understand how your iPod's pausing behavior could have been affected by removing it.

My iPod does pause when I turn off the engine while listening to it. When I start up the car, say the next morning, the iPod picks up right where it left off. (I just checked this morning.) But I think I read somewhere that the iPod doesn't stay in this pause (or standby) state forever. Eventually it shuts down completely. But I don't know how long that takes. A day? A couple of days? I'm pretty sure I've seen it happen, maybe after leaving the car off for a weekend.

krue92

We replaced my old one with this brand new one, and I know my old one didn't function this way. If the resistor has nothing to do with it, maybe there is something else wrong with the module. It sounded to good to be true...

Nick@DICE

reset your iPod, that may fix it.

krue92

I did reset the Ipod and that didn't help. My shop still had one of my old modules they haven't sent back yet. We swapped that out and now it is working like it is supposed to.

Nick@DICE

Wildz!

Plainvillian

I have the same problem with my TL. Low XM and noise. Nick, do you recommend removing the resistor? That is not a problem for me to do. I assume you leave the circuit open and don't rejump anything?

Thanks

nalek

iTrader: (1)

Nick is long gone, doesn't work at DICE anymore (that I know about).
Best bet is to call them.

Plainvillian

Thanks for the info

firstacuratl

iTrader: (2)

Sounds like a PM to ffej is in order if he's still around. I just had Dice R3 installed and had none of these issues Now if I could just remember what buttons do what functions ... burned too many brain cells in my younger years to remember all this shite

ffej

I would go ahead and remove the resistor, assuming you can identify it as I described it (that is, assuming Dice hasn't rev'd the circuit board since then). You don't have to jumper anything back -- I just cut one of the traces to the resistor with an X-acto knife, and that was that. I've been using the modified Dice unit for a year now with no problems other than the occasional (one a week or so on average) drop in volume, which had been happening before I made the mod anyhow.