Grounds for dismissal

[arex]

To put these questions in context; while I'm familiar with basic electronics, I'm very new to car audio and the nomenclature involved in it. I'm building an adapter harness to mate a new HU to a factory amplifier, and I'm confused by something.

I understand that there are different sorts of grounds, but I'm a little unclear on how and when to isolate them from one another. Also, I've run into three different references to grounds between the HU harness, the adapter to the factory harness, and the line out converter, and I'm not sure how they all go together.

1. Chassis Ground - I know what this one is. There's one on the factory harness and the line-out converter.
   
2. Ground (SLD) - I don't know what SLD means. This is on the factory harness.
   
3. Ground - This is on the HU harness. I don't know which of the previous two this would be. If it wasn't for #2, I'd assume it was a chassis ground.
   

Can anyone please clarify this for me?

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[DukeNut 10+ year member]

what vehicle and new hu are you using?

 

[hispls 5,000+ posts]

Ground is Ground. Any metal attatched to the frame and/or - battery terminal.

No idea what SLD stands for, but - and ground in a 12V environment are synonymous and particularly with small current draw items they're pretty hard to screw up. In fact many Head Units will find ground through the antenna even if you didn't have the black hooked up.

 

[arex]

what vehicle and new hu are you using?

It's a 2005 Toyota Tundra Access Cab, with the non-JBL "premium" system, with the Panasonic amp under the right rear seat and tweeters in the front doors. I've read some things that seem to imply that the amp turn-on signal is a TTL pulse, not 12V. I hope not, but that's not insurmountable.

And...it's not exactly a new HU, it's a lightly-used Pioneer T1808 out of a 2008 Scion, which would give me MP3 and iPod interface capabilities. I was assured by several people on a Tundra forum that it was a direct swap, a 15-minute job to install. That hasn't been the case, since I have the "premium" system.

The connectors on the back of the T1808 are standard Toyota 10+6, nothing tricky there. The sole connector on the existing HU (made by Fujitsu) is the same as on the JBL systems, and I'm hoping that the interface is wired the same as the JBL, since that's the only documentation I've been able to find so far. I'm assembling the adapter harness with wire nuts, in case I need to do some fiddling before finalizing it with solder.

 

The line out converter is a Scosche SLC-4. This unit seems straightforward.

 

[arex]

Ground is Ground. Any metal attatched to the frame and/or - battery terminal.
No idea what SLD stands for, but - and ground in a 12V environment are synonymous and particularly with small current draw items they're pretty hard to screw up. In fact many Head Units will find ground through the antenna even if you didn't have the black hooked up.

I found some wiring diagrams in the factory service manual that states that it's a ground for shielding. What's being shielded and why it requires a separate ground wire were not told.