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radio cuts off when i turn headlights on

  • Thread starter Thread starter mr2gq
  • Start date Start date Jul 27, 2011
M

mr2gq

Member
Jun 16, 2011
65
2
7
stockbridge ga
Jul 27, 2011
#1
  • Jul 27, 2011
  • #1
Like it says when I turn the headlights on hte radio cuts off. I just got this car and there was no radio in it and the plug for hte radio was cut. So i just ran speaker wire to all the speakers from the new stereo and a constant 12V to the battery and the accessory I found with my multimeter that originally want to the factory radio plug. When I check with my multimeter the accessory power wire looses its power when I turn the headlights on. Also I noticed after I first hooked it up and my kids was playing in the car the stereo would turn ON when you turn on hte headlights with out the key even being in it. Now its the opposite lol so idk wtf to do or where to start looking. Im thinking a relay? Any help would be great and soprry bout the long post
 

5.0Pilot

New Member
Feb 14, 2009
11
0
2
Oxnard, CA
Jul 27, 2011
#2
  • Jul 27, 2011
  • #2
You didnt mention where you grounded your deck. If you have a bad ground, some units will shut down when they dont receive enough voltage, your lights might be doing that. that happened to my brother's 85 and a new ground strap to the block fixed that.

Another posibility is that you could have wired the ground or switched 12v lead to the dash light lead, causing the curcuit to break whenever your lights go on.
 
M

mr2gq

Member
Jun 16, 2011
65
2
7
stockbridge ga
Jul 27, 2011
#3
  • Jul 27, 2011
  • #3
Its grounded to the metal bracket thats bolted to the floor in the stereo din where it sits. And this 12v acc is the one that was originally in the factory stereo plug., This is a 91 gt btw
 

HISSIN50

"How long does it take to get help in here?
15 Year Member
Nov 29, 1999
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Jul 27, 2011
#4
  • Jul 27, 2011
  • #4
Why not just use a different accessory source?
 
M

mr2gq

Member
Jun 16, 2011
65
2
7
stockbridge ga
Jul 27, 2011
#5
  • Jul 27, 2011
  • #5
Well the funny thing is my dash lights aren't working now either an as I said when my kids was playing in my car an turned the lights on the stereo turned on with out the key in. Now it the opposite. If I turn the lights on the stereo shuts off an my dash lights aren't working still either. I think it's a ground or something
 

mustangkarl

Member
Feb 23, 2011
31
2
8
Ashland Wi
Jul 28, 2011
#6
  • Jul 28, 2011
  • #6
there is a dimmer ground at the radio, i accidentally used this as a ground for the radio and had the same issue. i can't remember what color it was orange and black or green and black i really can't remember.
 
M

mr2gq

Member
Jun 16, 2011
65
2
7
stockbridge ga
Jul 28, 2011
#7
  • Jul 28, 2011
  • #7
mustangkarl said:
there is a dimmer ground at the radio, i accidentally used this as a ground for the radio and had the same issue. i can't remember what color it was orange and black or green and black i really can't remember.
Click to expand...

The 12v acc wire im using for my stereo is orange and black. im going to try and unhook it and see if my dash lights work again. I just dont see how it would be a ground wire when it has 12v going to it with the ignition in the " ON " position. All I do know is that the 12v goes away from that wire as soon as I turn the headlights on lol. I tried adding another ground strap to the engine I had laying around. Obviously didnt change anything. Thanks for the suggestions guys
 

jrichker

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Jul 28, 2011
#8
  • Jul 28, 2011
  • #8

Diagram courtesy of Tmoss & Stang&2birds



See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring Mustang FAQ - Wiring & Engine Info Everyone should bookmark this site.

Ignition switch wiring
http://www.veryuseful.com/mustang/tech/engine/images/IgnitionSwitchWiring.gif

Fuel, alternator, A/C and ignition wiring
http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

Complete computer, actuator & sensor wiring diagram for 88-91 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/88-91_5.0_EEC_Wiring_Diagram.gif

Complete computer, actuator & sensor wiring diagram for 91-93 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/91-93_5.0_EEC_Wiring_Diagram.gif

Vacuum diagram 89-93 Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/mustangFoxFordVacuumDiagram.jpg

HVAC vacuum diagram
http://www.veryuseful.com/mustang/tech/engine/images/Mustang_AC_heat_vacuum_controls.gif

TFI module differences & pinout
http://www.veryuseful.com/mustang/tech/engine/images/TFI_5.0_comparison.gif

Fuse box layout
http://www.veryuseful.com/mustang/tech/engine/images/MustangFuseBox.gif
 

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