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Discussion Starter · #1 ·
Basic info: Have kenwood doube din headunit, hornblasters horn with viair compressor and bumper mounted led light bar. Ok so the issue i am having is with the radio. Originally i would hit the horn and i would lose all sound out of the radio. Only sound, everything else worked. Also if the compressor was running and kicked off, i would lose sound. If i resarted the radio it would work properly until the next time i hit the horn or the compressor cycles off. Next i installed an led light bar, when the light bar is switched off i lose sound again. When i lose sound and turn the light bar back on i can hear slight static out of the speakers, if i cylced the light on and off multiple times, SOMETIMES i would get sound back but it was be very distorted. Between other mechanics, my employees, electricians i finally spoke to an electrical engineer from GM for hours at a time and he suggested i replace my relays, the ones for air horn and compressor and light bar, with a relay that has a diode. Well i did that and the light no longer kills the sound BUT the horn will still kill sound ONCE IN A WHILE. Any electrical advise here?

It just a pain to keep turn off and on the radio every time i lose sound
 

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That radio install requires a databus adapter to be done right. The databus adapter "should" have a ground wire. That needs connected to a proper ground. The steering column bracket fasteners are good place to ground it.
The radio itself also needs to be properly grounded. Run a ground from the radio case to the aforementioned steering column bracket fasteners.
 

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Discussion Starter · #3 ·
That radio install requires a databus adapter to be done right. The databus adapter "should" have a ground wire. That needs connected to a proper ground. The steering column bracket fasteners are good place to ground it.
The radio itself also needs to be properly grounded. Run a ground from the radio case to the aforementioned steering column bracket fasteners.
Sorry I forgot to mention, but did all the proper tests. Ran a ground directly to the battery, and positive and constant directly to the battery, still no change, I understand the radios are very susceptible to small voltage. This all started when I put in the horn. It also does it engine running and ignition only
 

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But, did you ground to the radio shell itself?

Also, where is the power tapped for the horn relay 12v?
 

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Discussion Starter · #5 · (Edited)
But, did you ground to the radio shell itself?

Also, where is the power tapped for the horn relay 12v?
Good point, I can't remember if I grounded the shell or not. And horn relay is pulling power from and auxiliary fuse behind passenger dash, not connected to the radio but in the same fuse block, I believe light bar relay is getting power from the same circuit.
I do remember when I disconnected ground the radio stayed on, it was pulling ground from the antenna as well
 

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Discussion Starter · #6 ·
But, did you ground to the radio shell itself?

Also, where is the power tapped for the horn relay 12v?
Spoke to the guy from GM, told me grounding the case will only cause a shield around the radio for RF, my problem is with current. Hes gonna give me some diodes to put inline of the relay to stop the spike the radio is seeing causing the internal amp to short out
 

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Diodes don't go inline, they goes across the relay coil.
 

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Discussion Starter · #8 ·
Diodes don't go inline, they goes across the relay coil.
It already has an internal diode in the relay, he wants me to put one inline, he'll show me where. Said that somewhere there is a spike of 12v going into the frame, that spike is shorting out the radio internal amp
 

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Discussion Starter · #9 ·
Still havent figured this out, have not put the diodes in yet.
Was driving the truck the other day and hit the horn once, it was fine, second time the radio shorted and got real loud and static was bad. The second time the pump came on at the same time as i hit the horn. Still not sure whats shorting it out
 

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Doesn't the databus run at 5 volts. Some one had a problem, where it turned out to be the connector to the radio allowing 12 volts to be interjected to the bus. The radio interpreted this for requesting max volume.
 

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just repaired a radio issue with my 2007, the sub and head unit would cut out under a hard thump, or would cut out when i turned my light bars on or the compressor kicked in. turned out to be a bad power connection right at the battery on the secondary main feed. the power wire that ran for the ecm, starter and stuff was good but the aux had a ton of voltage drop under load. found it with my old school test light, one end clipped to battery + then with the compressor on i could touch the test lamp to the stud on the fuse block and it lit up. fixed the connector all is good now.
 

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Discussion Starter · #12 ·
I'm definitely going to look into this, I'm pretty sure I cleaned all the connections but it's worth a double check

The other day I hit the horn a few times and the radio went to static and get ridiculously loud to the point where it scared the crap out of me.i had to turn off the radio
The first 2 times I hit the horn it didn't do it but I guess hitting the horn AND the compressor kicking on caused the issue
 
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