Dash Lights Come On When Ignition is ON

Wiring, lights, heater controls, anything electrical..
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archlab
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Dash Lights Come On When Ignition is ON

Post by archlab »

I can't figure this one out - driving me nutz:
1968 D100
Problem: When Key us Turned to Start Ignition (in 'Start' & 'Run'), the Dash Lights come on & Stay On.
Background:
1) Chk'd Wires from Gauge Cluster:
a) The 'Black' ones for the Dash Lights: These are wired correctly - They go to the proper
Fuse Block location.
b) The 'Light Brown' wire from the Light Switch: This is also wired correctly & goes to the
proper Fuse Block Location.
c) No other wires are interfering w/ the 2 (BLK & Lt. Brown) wires.

2) Light Switch:
a) When Ignition Key is 'OFF', the Dash Lights stay off unless the Lt. Switch Knob is rotated
Cntr-Clockwise (as it should do).
b) The Light Switch is working properly for all other modes

Speculation:
1) I have considered that the prong for the 'Light Brown' wire is malfunctioning, but have
swapped in two other Lt. Switches only to have the same result of 'Dash Lights' on when the
Ign. Key is On.

2) Could it be possible that the Ignition Switch wires are wrong? (note: The Ign Wires are not
'harnessed', that is, they each go into the Ign. Switch individually, so they could be all wrong.
I can't seem to find a simple picture of the back of the Ignition Switch to verify which wires go
to which Ign. connector (i.e. - Does the 'Lt. Blue' Wire (from the Windshld Wiper Switch) go to
'ACC', or does it go to 'BAT'?? etc)

I think if someone has a picture of the back of the IGN. Switch, or could tell me which colors go to which connector, I could probably figure this out. Note: I have the diagram from the Manual, but as usual, the colors don't match what I have (& these wires all appear to be original).

Electrical geniuses, I beckon ye!

archlab
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Re: Dash Lights Come On When Ignition is ON

Post by archlab »

Also, more Background:
...3) I have bypassed the Ammeter, so that the only Elec Pwr going to the Cluster is from the Dash Lights, plus turn signal lts,brake lt. & fuel gauge

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pwadventurer
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Re: Dash Lights Come On When Ignition is ON

Post by pwadventurer »

The fuse block has two halves, one half is hot all the time, the other is controlled by the ignition switch. The fuse for the instrument lights is a single fuse by itself powered from the light switch. Check and see if there is "by mistake", a wire tied into the instrument lights fuse from the ignition switch side of the fuse block or another key on source. There should only be a tan wire from light switch, and a black wire to the instrument lights.

Rick

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