Hey all, I'm getting ready to attempt my first car stereo install: Benz E320 wagon headunit swap using stock amp/speakers. Apparently simple, yet no installer will touch it.

Can anyone recommend a soldering iron and the appropriate solder to connect the wiring harness wires? I know nothing about soldering, so any tips for connecting the wires are appreciated.

I may try to install the empeg and keep the stock deck. Between the stock deck and the female harness coming from the dash will be a bunch of source switching, etc. Do you think anyone makes a female harness (same as what comes from the dash), which would give raw wires coming from the stock deck? I could then solder on RCAs from the stock deck.

Lastly, can the power wires from the female harness (coming from the dash) power two headunits and how can I split the power wiring? I'll have a male-to-raw-wire harness coming out of the dash, but can I wire both head units' power wires right to that harness, or do I need a switch box?

Thanks all. I really wish an installer would just do this.....

See my post about tap-ins. The car I recently bought has a stock amp that should work with empeg. I was going to use the tap-ins to put RCAs on the stock amp input wires without cutting-off the stock harness. Unfortunately, I haven't even started this project because I'm still wating for something to finally be released. The tap-ins may help your situation, but I'm having trouble figuring out what exactly you're trying to do with the stock deck. I probably just don't know MB's head units well enough.

As for soldering, I don't think you can beat Cold Heat for just soldering wire together. While I'm no soldering expert, I have been doing 2-3 audio installs per year for a while now and Cold Heat makes things so much easier/quicker. I wouldn't mind helping you with this project. Shoot me a PM if you would like me to come by...

Forget the soldering, and get a wiring harness adapter for your car if at all possible. Or use tap-in's as Rob suggested already. Or crimp style connectors.

Cheers

Exactly what Mark said, forget the soldiering. In my car I had a fair few cables to join, and they were all done in the same way with crimp terminals.

I did not cut into any of the cars wiring. My car audio shop had a fairly comprehensive set of ISO adapters and converters which I hacked into.

Thanks for the tips. Tap-ins seem a little less then perminant, but if I butcher the soldering effort, they will be a good backup.

Maybe I'm messing up the terminology, but I have a wiring harness to convert the female amp input from the dash into raw wires. Solder RCAs onto that for the source switcher and I'm good.

But I wonder if they make the opposite of that piece: female connector to raw wire; just like what comes out of the dash. Then I could connect the female end to the stock deck and solder on RCAs to the raw wire. It'd let me reuse the stock deck in a two headunit setup, saving me from buying an empeg tuner or cd/radio headunit.

But worst is the power. Can I just join the car's power line to both headunits power lines; in a Y? Or do I need some special "power splitter"?

Maybe I'll just stick to the empeg for now.

What you're looking for is generally called a reverse harness, I think. Obviously mercedes could sell you one, but they'd probably want to sell you the entire wireing harness for the front half of the car. Metra/Schosche and the like may or may not make one. They do for Honda, and for standard ISO head units.

As to power, your plan sounds good to me.

If you're just trying to solder two wired with striped ends, you really don't need much. A radio shack $12 soldering kit should be fine. Read Patrick's tuner manual for a introduction to soldering, it's for small electronics, but it'll help with your gobs-of-solder technique that's needed for this application.

Matthew

Awesome, thanks for the tip and the keywords. I spend a good chunk of search time just looking for the appropriate keyword to search for. The stock headunit in question has a fairly straightforward connection (despite what everyone says) so there may be a reverse harness. Thanks.

Rob, it's a good thing I double checked your link for Cold Heat. The sponsored link that Google gave me for Cold Heat almost guaranteed that I wouldn't buy it. I'm cautious of anything "as seen on TV", with not one but two free gifts, and taking "2 to 6 weeks for delivery" (at bottom of page, which is unnecessarily https at that).

I'll pass on Cold Heat more because I like corded tools. Disposable batteries are a waste, I can never get rechargeable to last long, and Murphey ensures that I never have them when I need them. I'll try my luck with a burn-the-house-down variety.

And thanks for the offer to help install the deck. I'd take you up on it if my house weren't a disaster area and if my yard didn't look abandon. Too busy to clean, for now.

Dude, I buy cars that I've "seen on TV." Just because it's advertised on television doesn't make it garbage...

You could buy it at Radio Shack if you want. It's located right next to the "real" soldering irons. Don't like it, bring it back.

Saying you won't buy something that's as seen on TV is incredibly close-minded. Think Geek even sells it.

By the way, it does eat batteries like candy. But, being able to solder efficiently in the car without burning yourself or the car's interior is well worth it.

I wouldn't use cold heat on electronics, but you're just soldering wire together.

I think he fears this as seen not all products advertised on tv. Most of the time this kind of as seen on tv stuff is garbage.

Another question before I start. I have to solder up to three wires to one wire - two headunits and source switcher to the wiring harness. Is there a proper way to do this? Twist three wires around the one and solder? Strip the harness wire way back and attach the other three at different spots? Then cover the entire mass with heat shrink, but won't it split because it can't seal the end with three wires?

I've finally got (most) all of the equipment, but hardly any knowledge.

As others mentioned, you want to avoid solder whenever possible. T-taps are a great way to merge wires together. Also available are "wiring nuts", where you first twist the wires together and then screw the nut down over where the wires are twisted together.

Solder has the unfortunate property that it doesn't withstand a whole lot of strain. Six months ago, I soldered all the connectors in my empeg harness. Now, some of them are starting to come loose again. Very frustrating.

I guess we just have to agree to disagree here. I think soldering and shrink tubing wires on car installations (when done properly) is much more reliable than t-taps, wire crimps, or wire nuts. Your point that a solder joint won't handle strain is well-taken, but I don't think any of the non-soldering options are much, if at all, better in that respect.

To answer the question about three-wire soldering: Yes, just twist all three together, coat the wires with flux, and solder away. Shrink tube the whole thing.

I agree with Tony I have found soldering to be much more reliable.

I agree with both Dan and Tony I used to have problems with my crimp joints because I was using the wrong connectors and I was trying to crimp them with a pair of vicegrips. I also used to have a lot of problems with my solder joints until I learned how to solder properly and properly apply the heatshrink tubing, which helps keep the joints from being stressed in ways that can cause them to break. The reality is that both methods can be very bad or very good. It all depends on having the proper tools and experience to get good solid connections.

If crimping is so unreliable, I have to ask why does basically every vehicle manufacturer use crimps everywhere and particularly on things like engine wiring harnesses? Done properly, crimps are better for automotive.

That said, for a stereo install either is fine in my opinion when done properly. Soldering should never provide any real mechanical strength for a joint. It only provides the electrical connection.

Although crimping should provide more physical strength, I have found one of my wires still split over time, so I rewired and fixed my wiring more securely so the g-force wouldn't make it move so much.

It is still much easier to install / uninstall than soldering though.

Molex: "Quality Crimping Handbook":

http://www.molex.com/images/products/apptool/qual_crimp.pdf

Soldering IMO is way better if done correctly. I hate to brag (OK maybe not) but after 20+ years of soldering my soldered speaker wire connections will be as strong as the wire. The key is messing the wires together (not just wrapping around) and getting good solder penetration with good heat. The solder should be smooth and have a shine to it when you’re done. If it looks clumpy or has a dull finish you did not have enough heat or you moved it before it solidified.

The main reason people use crimped on connectors is because it is fast and takes little skill. Granted some crimp connections are good but just not solder good.

The main problem with crimped wires is corrosion and heat/cooling cycles that loosen the wires. With soldering you bond the two wires together so it will withstand corrosion and temperature changes better.

And heat shrink is the only way to go. If I have to use tape I make sure it doesn’t unravel by putting a small zip-tie around it. I’ve seen electrical tape come loose too many times.

Electrically, a crimped connection is highly-conductive-wire to highly-conductive-connector.

A solder joint has poorly-conductive (comparitively) tin/lead inserted between the two, producing more of an impedance mismatch, and therefore more signal reflection from the joint.

Cheers

For me, when I have a pair of soldered wires fail, it's not because I didn't create the joint carefully or strongly. It's because the flexing of the unsoldered wire right next to the solid solder joint frays and eventually breaks off.

As was stated elsewhere in the thread, this is somewhat mitigated by a decent bit of shrink-tubing, properly applied.

This debate is informative, answering some questions and raising more. I've probably gotten myself into trouble by choosing solder, but given enough time and information, I can learn the task.

The solder-type RCA connectors I'm using have a flat - solder post. Can I solder wire onto a flat surface? My cheap RadioShack RCAs have holes posts. The "high end" - is just a flat surface and the + is a depression to receive the wire. Tempted to drill a hole in the - receiver to thread the wire.

The RCAs are where strain relief is my biggest concern. I'm considering hot gluing or caulking the wires at the end of the connector to help them.

How do I better join two (or more) wires before soldering them? Should I twist individual strands from both wire, then twist together the whole mass? Seems like risking metal fatigue.

I chose clear thin walled heat shrink tubing, but it seems thin. I probably should have got the thick walled for stronger support... but I think it had a higher shrink temp that I didn't want to mess with.

I chose standard tin/lead solder (two spools: one with and one without flux) over 4% silver solder because I didn't think I could handle the higher melting temp of the silver.

Maybe I'll try testing some soldering and shrinking this weekend. Eventually I'll get it figured out.

Wire splicing, the NASA way:

http://workmanship.nasa.gov/guidadv_recmeth.jsp