Instrument lights and key buzzer no power

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Malsteif
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Instrument lights and key buzzer no power

Post by Malsteif » Sun Mar 03, 2019 9:01 pm

I tried to install leds in the 4 dash instrument housings, but after attempting the second one, they all went out, along with the key buzzer. All other interior lights are also non functional, such as the heater and fan lights , along with the hazard switch light. I’ve checked and then replaced all fuses in the fuse box and checked the two online fuses near the ignition switch. I can’t figure out why the buzzer and the lights aren’t now functioning. I’ve even purchased new bulbs to no avail. Any tips or info would be appreciated.

1978 Fiat Spider 1800
Malsteif
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Re: Instrument lights and key buzzer no power

Post by Malsteif » Mon Mar 04, 2019 10:29 am

It was the rheostat/dimmer, thanks to Robert Thompson for his suggestion. The buzzer must have just randomly died at the same time.
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cgranju
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Re: Instrument lights and key buzzer no power

Post by cgranju » Mon Mar 04, 2019 11:15 am

oh, nice! Yeah, that rheostat is an evil POS thing on most of our cars.
Chris Granju
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owner of a number of Fiats built prior to 1986
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jseabolt
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Re: Instrument lights and key buzzer no power

Post by jseabolt » Wed Mar 13, 2019 9:45 pm

cgranju wrote:
Mon Mar 04, 2019 11:15 am
oh, nice! Yeah, that rheostat is an evil POS thing on most of our cars.
Apparently the dash light dimmer is a US DOT required thing. As well as the door chime.

As if you really need to dim the dash lights on a Fiat.

I found if you just bypass the dimmer with a jumper wire it seems to make the lights a little bit brighter. It seems that thing when set to full illumination, still acts as resistor!
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cgranju
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Re: Instrument lights and key buzzer no power

Post by cgranju » Fri Mar 15, 2019 12:44 pm

good point. If anything, the knob becomes a randomly activated on/off switch in many cars. I concur. I like the idea of a dash light on/off switch (which I did in my '79 x1/9 since the lights on those are oddly wired to always be on), but I don't need a dimmer. Maybe with LEDs?
Chris Granju
sunny East TN
owner of a number of Fiats built prior to 1986
spider2081
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Re: Instrument lights and key buzzer no power

Post by spider2081 » Sat Mar 16, 2019 8:24 am

The dash light dimmer has an internal fuse. If there is even a momentary short to ground anywhere in the dash light circuit it will blow. This makes the dimmer inoperable. The fuse is spot welded inside the the control. I have opened the dimmers and installed a single strand (one of the 19) from a # 16 wire. I solder it in place of the original fuse wire. It seems to be sufficient for the dash lights to work.
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jseabolt
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Re: Instrument lights and key buzzer no power

Post by jseabolt » Sat Mar 16, 2019 9:24 am

spider2081 wrote:
Sat Mar 16, 2019 8:24 am
The dash light dimmer has an internal fuse. If there is even a momentary short to ground anywhere in the dash light circuit it will blow. This makes the dimmer inoperable. The fuse is spot welded inside the the control. I have opened the dimmers and installed a single strand (one of the 19) from a # 16 wire. I solder it in place of the original fuse wire. It seems to be sufficient for the dash lights to work.
Somewhat on the subject. The wiper speed knob is about to give up the ghost. I don't really know how to describe it but instead of going from one position to another (click, click), I have to rotate mine a bit further from slow to fast, like something inside it is about to break.

I looked to see if these were available new. Probably not that much. I can't seem to find any new ones and the used one on EvilBay are priced quite high. Maybe nobody is making replacement switches. I have a spare speed switch (somewhere) but have no idea where it was at the time.

I ended up finding a universal wiper controller knob for $13 including shipping:

Image

https://www.ebay.com/itm/Speedway-Motor ... 7645!US!-1

The day after I ordered it, I was looking through a box of stuff for something else when I ran across this spare wiper speed controller knob from that 81 model! That's what you get when you are a parts hoarder and can't remember where you put stuff!

Thought I'd pass this along in case you guys are like me and are on the cheap and will use anything else that would work to save a buck.
paulc
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Re: Instrument lights and key buzzer no power

Post by paulc » Sat Mar 16, 2019 4:21 pm

Replaced mine with a SPDT toggle switch when I replaced the dash with a California unit
Used a custom label that says FAST-SLOW
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