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whe42

electrical problems

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I have a 69 mustang 6cyl 250. I put in a new radio but now have no power to the radio. I tested the two wires with a volt meter and got nothing. I checked the fuse which is intact but do not get power on either side to the fuse. if there are any common places for a short to occur that would be helpful . I also have no power to cig lighter and heater and under dash lights if that helps.

I did the following

1. The headlights work
2. the engine cranks
3 when placed in acc fuse #1 , #3 and #7 work on both sides of the fuse. Fuse #5 has no power on either side of fuse and fuse 6 has power on one side and not the other. The fuse is not blown that I can see. This is the same on acc and on position
4. fuse #5 has no power at any time.
5. fuse #6 has power on one side but not other and fuse appears intact.

I'm not sure where to go next. Do I need to replace the fuse holders. I tried cleaning with sandpaper.

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If you have no voltage to center two clips (BATT) on the bottom of the fuse box, the most probable cause is that the wire going to the back side of the fuse box has broken off.  I see this about 10-15% of the time.  Disconnect the battery, remove the fuse box and inspect the two large wires where they attach to the center taps of the fuse clips on the back side of the fuse box. 

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image.thumb.png.01eb9722cfe9baee7a44c00a94b377a6.png

#37 feeds fuses 6 and 7, and 7 works. It sounds like the output side of fuse 6 has a bad connection in the fuse clip, or possibly the connection to wires 40 and 54.

Do you have power on fuse 5 if you turn on the light switch? This feeds a string of lights...dash, radio, heater, clock and ash tray.

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R the battery wires connected directly to the black fuse box or r they on the green? Box/plug that plugs in to firewall and that the fuse box sits over?

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the fuse block and green piece on the drivers side firewall plugs together. If u remove the bolt in the center and release a couple of clips on the green piece it will unplug. The larger pin on mine was burned and had to replace with new pins. I have also found problems where the wires are riveted to the conductor bars on the fuse block.   

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2 hours ago, whe42 said:

So then the battery wires I’m looking for are attached to black box under the green plug?

Yes the wires and joints u want to inspect are between the green firewall plug and black fuse block and u have to disconnect them to see it.  The two pieces plug together by male and female pins. Once you have center bolt loose and green plug unplugged by releasing the clips the fuse block if I remember correctly is held to the firewall by two screws that will have to be removed also.

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So I think I got the fuses working but heater radio and cig lighter don’t work. As I was tracing the wires I found several plugs not being used. Bellow are pictures can someone tell me what they r for. Also 2 silver  bodies attached to wires. I thought might b blinker solenoid but there r 2. Thanks

1 is by gas pedal

2 is by radio 

3 is bellow gauges on driver side close to door

4 has 2 both above glove box

5 is on passenger side of radio/air controls

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whe42 what are the colors on the plug to the left? BTW, the brake light switch plug is the one on the right with wires 511 Green, and 10 Green/Red

Lets see if we can further test Mid's Jedi powers

image.png.db76137f48f49d1109af135cd29ba03b.png

 

and what are these Mid? (Clock plug to the right)

image.png.df1881e197ff8963d074202945b8c43c.png

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The two female plug has yellow/black (radio power) and blue/red (radio lamp power).

The female plug in lower part of red circle is blue/red and is for lamp power for optional clock.  The orange spliced wire is probably power for the turn signal flasher can.

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and the brake light plug is what connects to the switch on the brake pedal correct? I won't be able to work on the car for a week or two. Work keeps getting in the way. Ha Ha!

I will try plugging in all the plugs where they go and see if that helps with what doesn't work. 

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So finally got to work on car again and got the fuses all to work and now the radio works as well. Thanks for the help with these issues. The next thing is the heater. The fan works when directly connected to battery but does not come on when connected internally. I assume that it is either the switch at the dash controls for fan speed or the switch resistor is broken though not sure.. How do I test these items. The videos I have seen suggest the negative feed goes through the resistor but on mine the positive seems to connect to the resistor and the negative wire to the fan is grounded to the metal on the side of the engine compartment. The video suggests touching each of the connectors on the resistor switch and see if each speed works and if so the dash control switch is bad and if not the resistor is bad. If this is correct do I use a positive wire and touch each of the connectors on mine? Is this correct and if not what do I do to test the other parts to find the problem. Thanks

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Some of the older cars do have the system you describe, but 69s do not. Ours is simplicity itself.

Probably the easiest place to start is the blower speed resistor. Visually inspect yours to see if the resistor coils are damaged. If you have an ohmmeter you can verify its operation by connecting to the terminals- where should be obvious. If you don't have a meter, just sticking a jumper wire in the back side of the plug will give test results (as described below).

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This shows the heater circuit in its simplest form as a schematic. Its good that the motor works, so finding the problem should be easier. The circuit driving the motor is identical in cars without air conditioning. Heater only cars just don't use the lower half of the schematic. 

image.thumb.png.526920288261c9257ac04ff1cf6fecd0.png

Above the red line traces the path for Low. Turn the key to Accessory or ON. You can see that it goes through both resistors in low, only the right resistor in medium, and goes directly to the motor in high. Does it work at any speed? If not the switch or fuse 3 could be bad. If it works on HI its one of the resistors or the switch. If it works on medium but not low, its the left resistor or switch. The diagram below is in the How To's section, and will tell you which resistor to jumper. This is page 2-E33 (just look for page 33). Oh, it only uses a 14 amp fuse if you only have the heater, but a 30 amp fuse if you have AC.

image.thumb.png.6da1a12c1bbff6fc520c5f2b6c7b863a.png 

Turn the ignition to ON or Accy, turn the heater switch to LOW. If it doesn't work, jumper 268 red to 269 blue (that's the left resistor on the schematic). If that doesn't work, jumper 269 blue to 270 black (that's the right resistor on the schematic). If that doesn't work jump 268 red to 270 black and that will bypass both resistors.

If you still can't figure it out, tell us your symptoms.

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Yes my fan worked prior to installing but now does not work at any speed and I’ll recheck fuse but were all working last week. I was thinking switch might b the problem but wasn’t sure

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Yes 257 should have power. Yes connect to 257 and the other end to chassis- should be around 12vdc. Edit: with the key in Accy or ON

 

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As previously stated, fuse 3 will be 30A with AC or 14A if heater only. If you don't have power on 257 (with key on), check both sides of fuse 3 (key on). If the inboard side of fuse 3 doesn't have power, check both sides of fuse 1 (key on). The object here is to ascertain if there is a loose wire on the back side of the fuse block. There is a remote possibility that ignition switch B to A is defective, but that runs lots of things and should be noticeable, especially on a Tach car.

FYI, fuse 2 is normally only used by Cougars, as they have more "stuff" that needs power than a Mustang.

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So I now have heater and radio working except light for heater dash area. I don’t get power to wire that goes to it. I tried with acc. On and off. I also replaced bulb. Any thoughts? Also as I was reinstalling dah the piece fell out on passenger side from dash does anyone know where it goes? Thanks

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Look in the "How To's" section for the wire diagram and schematic:

image.thumb.png.8890759bc71cafec2ea6be292a24a07f.png

The key doesn't need to be on, the light switch can be in Park or ON. Turn the knob CCW to the stop, and the following lites should be on: ash tray, heater, radio, clock and 8 dash lights. Wires 19A thru E are blue with a red stripe.

The schematic follows:

image.thumb.png.0aa01978d6c980c6c1725f56bd84f17c.png

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