White "Dash Light" wire - no power

[scrubs]

Need help from an electro-wizard...

I wired my dash today (using WAGO connectors, see other thread) and light and needles worked on the bench.

I then: 1) connected feed gauge (brown) to my red, 2) connected dash lights to my white, 3) connected to one of the unused grounds

Tried to test by turning ignition to on position: the needles move, no lighting. Same thing on ACC.

1) 12V at feed gauge wire (including the unused one)
2) 0V at dash light wire (including the unused ones)
3) Diconnected the dash harness plug that carries the "dash light" wire: a) dash light wiring in continuity from plug to where I inserted to WAGO
4) 0V at main harness plug "dash lights" pin (gauge feed is in same plug and pin has 12V)
5) All fuses intact

That white wire seems to go in the harness and disappear, I think from the wiring diagram it goes to the headlight switch. I tested there and 0V, the other headlight switch points have voltage and there is continuity between the points.


Where does this "dash lights" wire get fed from? I cannot see on the wiring diagram and would I need to dig into that large trunk to find the issue there?

Can I use the other unused gauge feed (has 12V) wire to feed the gauge lights or is that too much current for that circuit or will diminish the brightness/function?

Can I just use a wiper/radio/heater supply (also ACC fed) since I am not running any of those?

Am i way off?

thanks,

j

[i.e.427]

Dash "lights" get powered from the "light switch" as in headlight switch. That way they come on at night, when your headlights are on. Turn the dimmer portion of the headlight switch it may be set to a point that the dimmer is not supplying enough power for the LED's to light. Did you try that?

[scrubs]

Dash "lights" get powered from the "light switch" as in headlight switch. That way they come on at night, when your headlights are on. Turn the dimmer portion of the headlight switch it may be set to a point that the dimmer is not supplying enough power for the LED's to light. Did you try that?

Tried the rotating the headlight switch to various positions with the switch in/out, no luck.

Retried the gauges off the harness and get both lights and needles.

Bad switch?

[rich grsc]

Sound like the headlight switch could be wired wrong.

[scrubs]

OK, brief chat with FFR this AM.

According to the tech, I won't get power thru that "dash light" wire until the entire (yes, I asked, "entire") electrical system is in place. He said the headlight switch is the "brains" of the circuit and with missing components, it won't work.

Honestly, I don't get it, wires not being my strong suit, so I will forge ahead and report back later - because things like headlights/tail lights etc wont be on the car for a while. May be a bad idea, but will trust him for now. At least I know i can drive the car during the daytime hours:)

Thanks for the replies.

j

[Tooth]

You actually spoke with someone there? That's impressive. I'm following your progress closely on this as I'm going to start my dash wiring this weekend.

Thank you for keeping us updated.

[edwardb]

OK, brief chat with FFR this AM.

According to the tech, I won't get power thru that "dash light" wire until the entire (yes, I asked, "entire") electrical system is in place. He said the headlight switch is the "brains" of the circuit and with missing components, it won't work.

Honestly, I don't get it, wires not being my strong suit, so I will forge ahead and report back later - because things like headlights/tail lights etc wont be on the car for a while. May be a bad idea, but will trust him for now. At least I know i can drive the car during the daytime hours:)

Thanks for the replies.

j

Hate to disagree, but NO. I'm assuming you have the headlight switch plugged into the RF harness connector intended for the headlights. It's pre-wired, so nothing you need to do other than plug it in. There's also a ground wire that should be connected to the switch. I'm also assuming you have the the TWO red wires attached to the BAT connection on the ignition switch. One labelled RED IGN SW - SOL. This is your main +12V feed from the battery. Since you have other stuff working, e.g. gauges, have to assume this is connected. The other is labelled RED HDLT SW & FEED. If you follow the wires in the wiring instructions schematic (important to use and understand BTW) you will see this last wire goes to the headlight switch and provides battery, e.g. always on, power to the switch. So your running lights, headlights, courtesy lights, and dash lights all work all the time, e.g. no matter position the key is in. The dash lights should light at the first (running lights) and second (headlights) position of the switch. Assuming of course it's not turned all the way down. For testing, you should turn the headlight knob all the way counter clockwise. Against the stop for the courtesy lights. That feeds the full +12V to the dash lighting circuit. There's absolutely no other reason additional wiring (e.g. "brains") in the electrical system are required for this circuit to work if wired correctly. Unless the switch is bad, and that's possible. Have you tried any of the other lights, e.g. front or rear running lights, headlights, etc.

[scrubs]

Hate to disagree, but NO. I'm assuming you have the headlight switch plugged into the RF harness connector intended for the headlights. It's pre-wired, so nothing you need to do other than plug it in. There's also a ground wire that should be connected to the switch. I'm also assuming you have the the TWO red wires attached to the BAT connection on the ignition switch. One labelled RED IGN SW - SOL. This is your main +12V feed from the battery. Since you have other stuff working, e.g. gauges, have to assume this is connected. The other is labelled RED HDLT SW & FEED. If you follow the wires in the wiring instructions schematic (important to use and understand BTW) you will see this last wire goes to the headlight switch and provides battery, e.g. always on, power to the switch. So your running lights, headlights, courtesy lights, and dash lights all work all the time, e.g. no matter position the key is in. The dash lights should light at the first (running lights) and second (headlights) position of the switch. Assuming of course it's not turned all the way down. For testing, you should turn the headlight knob all the way clockwise. That feeds the full +12V to the dash lighting circuit. There's absolutely no other reason additional wiring (e.g. "brains") in the electrical system are required for this circuit to work if wired correctly. Unless the switch is bad, and that's possible. Have you tried any of the other lights, e.g. front or rear running lights, headlights, etc.

I did check the plugs on the harness, not a lot of ways to plug it incorrectly. I did check that sequence of the pins and thought they looked in order.

The headlight switch has the ground wire attached. Other spade connectors on the headlight switch have voltage, only the dash lights white is 0.


I will take down the tape on the ignition switch and triple check it.

I don't have anything else connected as I was following the build manual sequence, but will dig up some headlights to check.

Will break it all down and recheck everything.

Thx, the brains theory sounded suspicious.

Will report back.

[scrubs]

Is there a replacement switch part # to see if I can pick one up locally for a test?

[JJK]

the headlights do not need to be plugged in for the dash lights to work, I have verified on my build

[scrubs]

Is there a replacement switch part # to see if I can pick one up locally for a test?

Found it

[scrubs]

1) took a peek at the switch, seems hooked up ok:

182926


2) removed tape from my ignition switch, seemed ok:

182927


3) tested with ignition switch on the ACC/on positions along with the headlight switch turned all the way clockwise in the first and second positions.

I just don't understand why there is no energy in that white wire when the gauge feed does have power. It's as if that white wire is not connected to the main harness.


4) I unwrapped the radio wiring which I had put aside bcs of no plans for a radio and connected it...voila, lights and needles. So much for the FFR tech theory...as well as the bad switch theory. Unless I figure something else out, may just power dash with it, who care if they're on all the time:) - or can I add a switch to it...more research to do.

Possible the harness has an internal issue? My concern is if it does, will I have more issues as I keep building?

Happy that the dash lights up, but pretty frustrated.

Enough for one night. Thanks guys.

j

[D Stand]

182928182928

Made this drawing to figure out the functions on the headlight switch. Hopefully it will help you understand if you have it connected right and have it in the right position to turn on the lights. Edwardb explains it perfectly. The only added comment is, on mine, if you rotate the knob all the way clockwise, the lights actually turn off. Not sure if that is correct but that is what mine does. On mine, full counterclockwise is full on.

Dale

[edwardb]

182928182928

Made this drawing to figure out the functions on the headlight switch. Hopefully it will help you understand if you have it connected right and have it in the right position to turn on the lights. Edwardb explains it perfectly. The only added comment is, on mine, if you rotate the knob all the way clockwise, the lights actually turn off. Not sure if that is correct but that is what mine does. On mine, full counterclockwise is full on.

Dale

You're absolutely right. Counter clockwise on the headlight knob. Against the stop for the courtesy light switch function. That's where I leave mine all the time. Just went out to the car and confirmed. I wonder sometimes where my brain is at. No excuses. :p

To the OP, don't give up. Hopefully it's as simple as turning the knob the other way. Don't settle for lighting the gauges from another circuit. This isn't complicated and in hindsight whatever the problem is will probably be simple. You want them automatically turning on with the headlight switch. Which as I said before, is a battery circuit. You said you tested with the ACC on. The headlight switch is powered all the time. Regardless of whether the key is on or not. Same as the brake lights and emergency flashers. It's a safety thing. Test it with the key off.

I agree with the post that said the headlights don't need to be physically attached for the headlight switch (and gauges) to work. I only mentioned that as a test to confirm the switch had power and was working.

[scrubs]

You're absolutely right. Counter clockwise on the headlight knob. Against the stop for the courtesy light switch function. That's where I leave mine all the time. Just went out to the car and confirmed. I wonder sometimes where my brain is at. No excuses. :p

To the OP, don't give up. Hopefully it's as simple as turning the knob the other way. Don't settle for lighting the gauges from another circuit. This isn't complicated and in hindsight whatever the problem is will probably be simple. You want them automatically turning on with the headlight switch. Which as I said before, is a battery circuit. You said you tested with the ACC on. The headlight switch is powered all the time. Regardless of whether the key is on or not. Same as the brake lights and emergency flashers. It's a safety thing. Test it with the key off.

I agree with the post that said the headlights don't need to be physically attached for the headlight switch (and gauges) to work. I only mentioned that as a test to confirm the switch had power and was working.

OK....

Tested with key out of the ignition and switch turned full counterclockwise and position 1...lights. I guess that white wire is connected;)

Interestingly, when I turn the ignition to on/acc, I get the needles, but no lights again. Is this what I should be getting?

Regardless, thanks to the forum crew and particularly Edwardb for not letting me give up this issue.

[D Stand]

Have you started your car yet, or are you just testing circuit out now? Does the radio still have power when the dash lights go out? How above the courtesy light wire? All three of these items are fed from the same 15 amp fuse and should be fed right off the battery, see attached fuse block detail.



183054183054

[edwardb]

Interestingly, when I turn the ignition to on/acc, I get the needles, but no lights again. Is this what I should be getting?

Regardless, thanks to the forum crew and particularly Edwardb for not letting me give up this issue.

You're welcome and glad to hear the white wire/gauge backlighting is working. But doesn't make sense though that anything with the backlighting would change based on ignition key position. Reference previous discussion about the headlight switch power (where the white +12V comes from) is a battery circuit, e.g. directly tied to battery voltage. I'm out of suggestions. Something is possibly wired wrong or defective. But can't explain it.

[scrubs]

Have you started your car yet, or are you just testing circuit out now? Does the radio still have power when the dash lights go out? How above the courtesy light wire? All three of these items are fed from the same 15 amp fuse and should be fed right off the battery, see attached fuse block detail.



183054183054

No engine start yet.

[scrubs]

You're welcome and glad to hear the white wire/gauge backlighting is working. But doesn't make sense though that anything with the backlighting would change based on ignition key position. Reference previous discussion about the headlight switch power (where the white +12V comes from) is a battery circuit, e.g. directly tied to battery voltage. I'm out of suggestions. Something is possibly wired wrong or defective. But can't explain it.

Yeah, I agree. I have a new switch coming and will try that.

j

[RBachman]

Just a thought on this with something I ran into with connecting the white wire through to the light switch dimmer terminal. This is for a Vintage Gauge set with the daisy chain connectors on the gauges ordered several years ago. The LEDs were either on or off with the provided light switch. The issue was that the resistance of the switch and the LEDS were incompatible. I rewired the white wire to a 10-turn precision potentiometer. It's either a 1k or 10k, can't remember. https://www.amazon.com/gp/product/B079JN626M/ref=ppx_yo_dt_b_search_asin_image?ie=UTF8&psc=1

[edwardb]

Just a thought on this with something I ran into with connecting the white wire through to the light switch dimmer terminal. This is for a Vintage Gauge set with the daisy chain connectors on the gauges ordered several years ago. The LEDs were either on or off with the provided light switch. The issue was that the resistance of the switch and the LEDS were incompatible. I rewired the white wire to a 10-turn precision potentiometer. It's either a 1k or 10k, can't remember. https://www.amazon.com/gp/product/B079JN626M/ref=ppx_yo_dt_b_search_asin_image?ie=UTF8&psc=1

Not exactly. The issue with the Delco style headlight switch dimming function is voltage. Not resistance. It lowers the input voltage to dim lights. Which worked fine for incandescent bulbs. But not for LED's which typically stay lit at full intensity until they reach their voltage cut-off and then just turn off. Which is what builders experience when they use the kit supplied headlight switch with the LED backlit gauges. Using resistance is a way to adjust LED brightness. But can have varying results based on the LED, color, etc. I've played around with it and had mixed success. No doubt the linked potentiometer is on option. You have the results to prove it. The best solution though is usually via PWM (pulse width modulation) and there are dimmers that do that too. Basically rapidly switch the LED on and off for varying durations which affects the displayed brightness. Like this one: https://www.amazon.com/ALOVECO-Interior-Ceiling-Recreational-Lighting/dp/B07Y2XC225. I don't know if this is the exact one, but several have installed this kind of device and apparently works very well.