5.0L (1979-1995) MustangTechnical discussions on 5.0 Liter Mustangs within. This does not include the 5.0 from the 2011 Mustang GT. That information is in the 2005-1011 section.
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The dash lights in my 79 Pace Car will not work. All the other guages, oil pressure, temp etc work fine.
I put in a new headlight switch that did not cure the problem. I also went through all the fuses and found that the slot for the cluster illumination had a 15 amp fuse when it should have been a 5 amp fuse. I switched to a 5 amp as per the handbook. I then pulled the cluster and checked the bulbs as I thought maybe they burned out, but they are fine.
As well, my dome light will not come on when you open the doors, but it will come on when you turn the headlight switch all the way left. I don't know if this problem would be related to the cluster problem or not.
Does anyone have any other ideas or had similar problems?
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Is there a way to test the dimmer switch? It does switch the lights from low to high and back, so I didn't think that could be the problem.
If your dimmer is one of the old style aluminum case units then you need to set the meter to a low resistance (ohms) scale and probe across the two silver colored terminals. While holding the probes across the terminals turn the dimmer **** and watch the meter. It should be a fairly smooth increase/decrease in resistance without any 'drop outs' in the reading.
If you have the newer plastic case switch then you probe across terminals R & 1. The identifiers are molded into the case next to each terminal.
To trace for power follow the circuit diagram and check for voltage along the dimmer switch circuit. Take the negative probe and connect it to a metal chassis part/screw and take the red lead and probe the connection points along the circuit. The BR wire behind the main light switch that goes to the back of the dimmer is a good place to start. With the main light switch in the Park position you should have about 12v at both points
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5.0 Mustang & Super Fords July 2005
Well the new dimmer switch didn't work, in fact things got worse. The lights wouldn't even come on. I put the old dimmer switch back on the lights work.
I turned to testing the headlight switch. I noticed pin "A" in the wiring harness doesn't have a wire running into it. One of my tests is to test 12V running to A but there isn't even a wire there. That seems strange as it looks all stock.
Yes, I have taken the dash off and the instrument cluster, but I didn't see any crimped wires.
Right now I'm trying to find a diagram of the wiring harness for the headlight switch to compare to what I have.
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