Interior lights problem
05-01-2008, 10:30 AM
#1
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Interior lights problem
1978 l48 ---ok when I turn my headlights on none of my interior lights will come on...
the tach/speedo lights dont come on...the small gauge lights dont the shifter light doesnt come on ...nothing......
I tried turning the light **** that controls the brightness or whatnot....the dome light does still turn on but thats it.....
is there 1 fuse that connects all of them??? any troubleshooting ideas pleasE? thanks
the tach/speedo lights dont come on...the small gauge lights dont the shifter light doesnt come on ...nothing......
I tried turning the light **** that controls the brightness or whatnot....the dome light does still turn on but thats it.....
is there 1 fuse that connects all of them??? any troubleshooting ideas pleasE? thanks
05-01-2008, 12:47 PM
#2
Drifting
Clearly, check the fuse first. 5 Amp labeled "INST LPS" on top left
All CF'ers, this is my recollection, but it's been a while...please correct me if I'm wrong!
The red wire from the charging system (post 1) routes through the light switch to the fuse box. The brown wire (post 4) that connects to the banded terminals feeds the interior lights. The green wire (post 2) gets its power from the brown through the band which is connected to the dimmer rheostat by the spade that sticks up through the band (post 3). No wire is physically connected to post 3. Power is metered to the green wire by turning the rheotat (dimmer) ****. The green wire feeds back to the fuse box and emerges from the fuse box as the gray wires that progress to the instrument cluster,tach, shifter...
The dome light works a little differently...a copper blade at the base of the switch is forced to make contact with the metal switch body when you click it all the way, in essence completing the ground (white now connects to black) and closing the circuit.
Since your dome light and headlights work, if the switch is good the problem lies downstream of the green wire. If the fuse is OK, a good first step would be to check the switch itself...the rheostat on mine had been "burned" and the wire was broken so the circuit was lost. I replaced the switch and all lights were recovered.
A quick test of the rheostat is to remove the green wire from it's connector and insert it into the adjacent slot on the left so it actually connects to the spade at post 3...no wire will connect to post 2. This bypasses the rheostat and will give you full interior on when the switch is pulled out all the way. You lose the dimmer function but all the lights work.
Best of luck...if you go after the switch let us know if you need guidance on how to get out the tach/speedo cluster
Wave on, Steve
All CF'ers, this is my recollection, but it's been a while...please correct me if I'm wrong!
The red wire from the charging system (post 1) routes through the light switch to the fuse box. The brown wire (post 4) that connects to the banded terminals feeds the interior lights. The green wire (post 2) gets its power from the brown through the band which is connected to the dimmer rheostat by the spade that sticks up through the band (post 3). No wire is physically connected to post 3. Power is metered to the green wire by turning the rheotat (dimmer) ****. The green wire feeds back to the fuse box and emerges from the fuse box as the gray wires that progress to the instrument cluster,tach, shifter...
The dome light works a little differently...a copper blade at the base of the switch is forced to make contact with the metal switch body when you click it all the way, in essence completing the ground (white now connects to black) and closing the circuit.
Since your dome light and headlights work, if the switch is good the problem lies downstream of the green wire. If the fuse is OK, a good first step would be to check the switch itself...the rheostat on mine had been "burned" and the wire was broken so the circuit was lost. I replaced the switch and all lights were recovered.
A quick test of the rheostat is to remove the green wire from it's connector and insert it into the adjacent slot on the left so it actually connects to the spade at post 3...no wire will connect to post 2. This bypasses the rheostat and will give you full interior on when the switch is pulled out all the way. You lose the dimmer function but all the lights work.
Best of luck...if you go after the switch let us know if you need guidance on how to get out the tach/speedo cluster
Wave on, Steve
05-01-2008, 02:29 PM
#3
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Member Since: Apr 2008
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Clearly, check the fuse first. 5 Amp labeled "INST LPS" on top left
All CF'ers, this is my recollection, but it's been a while...please correct me if I'm wrong!
The red wire from the charging system (post 1) routes through the light switch to the fuse box. The brown wire (post 4) that connects to the banded terminals feeds the interior lights. The green wire (post 2) gets its power from the brown through the band which is connected to the dimmer rheostat by the spade that sticks up through the band (post 3). No wire is physically connected to post 3. Power is metered to the green wire by turning the rheotat (dimmer) ****. The green wire feeds back to the fuse box and emerges from the fuse box as the gray wires that progress to the instrument cluster,tach, shifter...
The dome light works a little differently...a copper blade at the base of the switch is forced to make contact with the metal switch body when you click it all the way, in essence completing the ground (white now connects to black) and closing the circuit.
Since your dome light and headlights work, if the switch is good the problem lies downstream of the green wire. If the fuse is OK, a good first step would be to check the switch itself...the rheostat on mine had been "burned" and the wire was broken so the circuit was lost. I replaced the switch and all lights were recovered.
A quick test of the rheostat is to remove the green wire from it's connector and insert it into the adjacent slot on the left so it actually connects to the spade at post 3...no wire will connect to post 2. This bypasses the rheostat and will give you full interior on when the switch is pulled out all the way. You lose the dimmer function but all the lights work.
Best of luck...if you go after the switch let us know if you need guidance on how to get out the tach/speedo cluster
Wave on, Steve
All CF'ers, this is my recollection, but it's been a while...please correct me if I'm wrong!
The red wire from the charging system (post 1) routes through the light switch to the fuse box. The brown wire (post 4) that connects to the banded terminals feeds the interior lights. The green wire (post 2) gets its power from the brown through the band which is connected to the dimmer rheostat by the spade that sticks up through the band (post 3). No wire is physically connected to post 3. Power is metered to the green wire by turning the rheotat (dimmer) ****. The green wire feeds back to the fuse box and emerges from the fuse box as the gray wires that progress to the instrument cluster,tach, shifter...
The dome light works a little differently...a copper blade at the base of the switch is forced to make contact with the metal switch body when you click it all the way, in essence completing the ground (white now connects to black) and closing the circuit.
Since your dome light and headlights work, if the switch is good the problem lies downstream of the green wire. If the fuse is OK, a good first step would be to check the switch itself...the rheostat on mine had been "burned" and the wire was broken so the circuit was lost. I replaced the switch and all lights were recovered.
A quick test of the rheostat is to remove the green wire from it's connector and insert it into the adjacent slot on the left so it actually connects to the spade at post 3...no wire will connect to post 2. This bypasses the rheostat and will give you full interior on when the switch is pulled out all the way. You lose the dimmer function but all the lights work.
Best of luck...if you go after the switch let us know if you need guidance on how to get out the tach/speedo cluster
Wave on, Steve
05-01-2008, 03:27 PM
#4
Drifting
