Radio momentary drop out

[ralt962 11]

Looking for suggestions here.  I went through the entire set of harnesses as they were laid out on a table.   So I thought I was in pretty good shape.  Now back in the car my one odd issue is that the radio will momentarily drop out when I turn on the turn signal.  I checked the power to make sure it was coming from the correct fuse.  The radio is a new Custom Autosound slide bar radio.   This is when the engine is not running.  Ignition in either the acc or run setting.  Battery is not all that good, but I put a charger on it.

I connected the auto trans shifter harness and I thought that solved it.  Not it happens most but not all of the time.

Looking for suggestions on where to go next.

[danno 128]

I wonder if you have a bad ground.  For the 69 factory system, the radio wire connections did not have a ground. The factory radio MUST be connected to chassis ground to work.  Have you got a good ground connected to your Autosound radio? 

With the radio dropping out when the turn signal is on, it certainly sounds like a low voltage on the battery.  Try turning on the fan on high with the radio on,  does it drop out then?   If the radio works with the engine running and not with it off, that is clearly a bad battery. 

[Mach1 Driver 560]

If you have Ford harnesses, then the radio circuit is on page 4 of the attached schematic.

As you'll see, there is no direct link to the turn signal circuit. If it isn't a ground issue as mentioned above, then you probably have a high resistance connection somewhere in the radio circuit, and since your battery isn't the best, the voltage drops below the operating voltage of the radio when the turn signals flash on. It doesn't happen with the engine on because the alternator is charging at around 14v. High resistance connections can heat up and melt things or cause fires, so try to find it.

The schematic is intended to show you how it works, and a wire diagram shows you how it is wired, with plugs etc. , so you'll need a diagram to track down the problem.

MUSTANG SCHEMATIC PG4.pdf

[ralt962 11]

Thanks,  I will check the ground.   That could be it.  Also I believe the schematic shows the old radio light on the same circuit as the flashers and other dash lights.  But then it wouldnt be on the radio fuse.

Is there a ground in the center of the fuse panel?  I have a book that seems to show one.

I'll need to charge the battery up much better before I recheck.

I am a newbie on this site, but I have to say you all have been very responsive and supportive.  Great Site!!!!

[Midlife 814]

No ground on the fuse box.  The factory radio power line is shared with backup lights, turn signal flasher power, and one of the wiper lines.  Your aftermarket radio power line is something none of us can know for sure---only you do!

[Mach1 Driver 560]

I assume you used the original radio power wire? I would measure the voltage at the radio with the flashers on. The radio will brown-out, then see what voltage that occurs at. It doesn't hurt to check the connections from ignition switch A to fuse #1, then from fuse #1 to the radio. If you find something- good, problem solved.

If you don't find something then I would get a new battery, charge it up, and recheck the voltage drop at the radio with the flashers on. Betcha that solves the problem. Happy hunting!

[ralt962 11]

I think you are right.  I will check the circuits first and ensure I have all the right grounds.  I didnt double check the ground to the radio yet.  But the battery is old and been sitting for a couple of years.  Likely the issue.

[ralt962 11]

Ground was fine.  It was the battery.  After charging for a while, turning on the turn signal didn't make the radio drop out.  But when I turned on the lights and high beams, then the turn signal, the radio would drop out.

I'm sure a fresh battery will solve this.