Hello Everyone, I have a 68 XR-7 that has no light on the dash. I have headlight all the light inside work but no dash light? What could it be? Can it be a bad light switch? They did work at one point.
I would check the fuse before spending money on a new switch.
This may be a dumb question but have you tried rotating the headlight knob side to side? That’s the dimmer function and it’s possible to turn the instrument lights completely off this way.
No I have not checked the fuse, I assumed if my headlight worked then fuse was ok but I will check. And as for the headlight knob yes I have turned for the dimmer but still no lights.
Many times people think the two radio wires are power and ground. In reality they are both hot. One for radio power and the other for illumination. The illumination lead gets grounded and it blows the fuse instantly resulting in no dash lights.
That was my problem with my dash lights. When looking at switch I found that the dimmer spring was busted.
I looked at all the fuses and they are all good, but still no Dash lights. I am not getting power to the blue/red wire that feeds the dash lights. I have installed a new headlight switch because the dimmer switch was busted so I thought that was the issue. What else can I check? I also don’t have power at the fuse for the instrument cluster
Not much else; the blue/red wire from the headlight switch goes directly to the fuse box. If you have power at the headlight switch (you can probe the back-side of the connector to see if you have any voltage) and no voltage at the fuse box, then the wire is busted somewhere in-between, or broken at the fuse clip base.
Not much else; the blue/red wire from the headlight switch goes directly to the fuse box. If you have power at the headlight switch (you can probe the back-side of the connector to see if you have any voltage) and no voltage at the fuse box, then the wire is busted somewhere in-between, or broken at the fuse clip base.
I have untaped the wires and followed best I could from the fuse box to headlight switch and wire looks good. I disconnected the headlight switch and I am not getting power from the blue/red wire. I have a lot of cables disconnected under the dash and don’t know where need to be connected too. The weird thing it was all working at one point. Can I connect a power source to that wire and see if it does power on my dash lights with my new Headlight switch?
That power for the blue/red wire at the headlight switch starts from the battery, goes to the thick wire on the headlight switch itself (typically black/orange and is 2 wires over from the blue/red), and is converted to blue/red via the rheostat on the headlight switch.
To test the circuitry, you can apply 12V directly to the disconnected headlight switch connector’s blue/red pin. You should have power at both fuse clips and all dash lamps.
Likely the fuse or the voltage regulator. Also make sure the dimmer rheostat is turned all the way up. If you do have a regulator that has failed, be sure to use a solid state replacement.
-Keith
Ok will do this weekend, if that works I need to find out what is going on with the wiring right? Did someone suggest if i am going to replace the voltage regulator? Is this one behind the dash?
The voltage regulator behind the dash cluster has nothing to do with dash lamps, only the gauges themselves.
Ok, I have applied 12v to the headlight switch and I do get power to the fuse. I have my dash disconnected so can’t check if power got to dash lights. The wires seem good. I have uploaded a picture and both connectors in orange are not connected to anything? I don’t have a radio yet where does the other connect too?
The 3 pin plug is an accessory dash lamp plug, used for optional equipment that you may or may not have: consoles, clocks, etc.
Ok weird then how do I get power to headlight switch? All looks well am I missing something?
Power to the headlight switch is from main battery power, reduced by the rheostat, and converted to dash lamp power (blue/red wire) all at the headlight switch, which goes now to the fuse box, and out to all of the dash lamps.
So there should not be power at the fuse box until the key is in and you pull out the headlight knob. Could it be a bad light switch? This headlight switch was for a different model and year. It has the same pins, headlight work and so does the vacuum ports.
1968-76 Ford Thunderbird with Hidden Headlights Headlight Switch
Manufacturer Part Number:
1AZHS00115
Brand:
1A Auto
Key does not have to be on for dash lamp power, only the headlight knob pulled out to park or ON.
How does this circuit work? does it get battery power then when the knob is pulled back it powers on the dash lamps? Could it be a bad head light switch?