I am in the process of installing a new headunit in my 94 LS400, and I ran into this problem:

1) Using a scosche harness that fits perfectly I soldered all the leads to the harness of my Pioneer DEH-P7700MP . I then proceeded to tyr an dturn on the deck. At first the deck did not turn on, after jiggling a few wires, I got power. Then I heard something pop and everything went dead.

I couldn't figure out if two leads touched and what shorted, so I went back and checked every lead, checked the fuse which was still intact on the headunit, and then insulated each lead.

Still can't get any power to the deck. So I decide to plug my stock headunit back in..

When plugging in the stock HU, I can't get any sound out of the speakers! I know it is playing the CD and sending some sort of output, because I have an amp hooked upto to the stock subwoofer output, and you can hear the sub play when I play a CD. However, all four door speakers are dead. Not even any noise/static.

I disconnected the negative battery terminal and reconnected it to see if that would reset anything, but it did not help.. I highly doubt that I blew out 4 speakers all at once.

What coudl have caused this? I'm at a complete loss.. any help would be greatly appreciated!

- Suneet

 

You could have possibly blown a fuse on your fuse panel for the radio or the amp.

 

Are there two fuses? i woudl think that if a fuse was blown I wouldn't get power to the stock HU at all, but I'm getting power + subwoofer sound + CD control. Also at the time of the "popping noise" the stock HU wasn't even plugged in.

 

First, NEVER turn on your power and test anything without first insulating all connections. Even though that was a mistake, we can't go backwards and prevent it, so....
1) You may have blown a power fuse, if you're lucky. Check these first.
2) You may have blown a fuse or circuit protection inside the headunit.
3) You may have toasted one or more of your output devices (internal to the headunit) by applying voltage where it doesn't belong, if any wires shorted, even momentarily.
If 2) or 3) is the case, you'll need to have the headunit checked and repaired by a qualified technician.

 

Turns out that it was a fuse. The STock HU was getting power from the CD changer cables and hence the subwoofer output was working, but the other cable fuse caled "RADIO1" in the engine bay was blown.

I'm an idiot for soldering those leads and then not insulationg them...

And I should have checked for that fuse first. I was just thrown off by the HU still getting power.

Thank you for your help!

 

You are one lucky dude! Easy solution, glad it worked out for ya.
Try using heat-shrink tubing on the soldered connections next time. You'll need a heat gun, and you'd need to remember to slide the heatshrink on before soldering. Elect tape also works, but can peel off.