Warning to replacement HU buyers
06-01-2003 | 07:16 PM
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From: Indian Land SC
Warning to replacement HU buyers
I just saw a Best Buys head unit installation in an S2000 today, and thought I'd post here to let y'all know of a possible issue.
Most of the time the adapter harness provided to connect an after-market HU to the factory radio harness does NOT have wires for the factory dash switches or mute button. You have to add them if you want to connect to those circuits (like Lucid does if you buy a DCI from him - he adds those wires to the harness).
But this install had wires for the dash switches and mute circuit in the adapter harness and they were colored purple and purple/black. The Best Buys installer wired them color-to-color to the HU, which connected the dash controls to one of the speaker outputs of the HU. This is an especially stupid move in this case, since this install did not use any of the speaker outputs on the HU - line-level only to a separate amp. He only connected one of four speaker outputs. What was he thinking???
It's not a good idea to connect a circuit that provides +12 volts DC (mute circuit) to the output of an audio amp (low impedance to ground) - one of them is going to win, the other will lose.
In this case it's the dash control panel that loses. It's not designed to supply several amps of current, like the HU amplifier is, so it's the one that gets toasted. Result - one bad dash control panel.
Moral - if you are getting an after-market HU installed, make sure whoever is installing it knows what they're doing. If you have any doubts, at least warn them to NOT connect the dash control panel wiring to anything on the new HU.
The factory Mute light should still work normally with a different HU installed - you should be able to toggle the Mute light ON and OFF by pressing the Mute button.
If the light cannot be toggled ON and OFF, or if it's dimly lit all the time, it's toasted.
Most of the time the adapter harness provided to connect an after-market HU to the factory radio harness does NOT have wires for the factory dash switches or mute button. You have to add them if you want to connect to those circuits (like Lucid does if you buy a DCI from him - he adds those wires to the harness).
But this install had wires for the dash switches and mute circuit in the adapter harness and they were colored purple and purple/black. The Best Buys installer wired them color-to-color to the HU, which connected the dash controls to one of the speaker outputs of the HU. This is an especially stupid move in this case, since this install did not use any of the speaker outputs on the HU - line-level only to a separate amp. He only connected one of four speaker outputs. What was he thinking???
It's not a good idea to connect a circuit that provides +12 volts DC (mute circuit) to the output of an audio amp (low impedance to ground) - one of them is going to win, the other will lose.
In this case it's the dash control panel that loses. It's not designed to supply several amps of current, like the HU amplifier is, so it's the one that gets toasted. Result - one bad dash control panel.
Moral - if you are getting an after-market HU installed, make sure whoever is installing it knows what they're doing. If you have any doubts, at least warn them to NOT connect the dash control panel wiring to anything on the new HU.
The factory Mute light should still work normally with a different HU installed - you should be able to toggle the Mute light ON and OFF by pressing the Mute button.
If the light cannot be toggled ON and OFF, or if it's dimly lit all the time, it's toasted.
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