Dash lights not working (SOLVED)

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KINGJOHN808
Posts: 127
Joined: Sat Feb 16, 2019 2:27 am
Location: Ewa Kai

Dash lights not working (SOLVED)

Post by KINGJOHN808 »

Aloha all. Searched using the “search” feature but could come up with a definitive answer.

My dash lights stopped working/don’t work, to include cigarette lighter bulb, HVAC bulbs, headlight “ON” indicator lights, fog lights “ON” indicator lights etc. the headlights, tail lights, fog lights all function as they should to include the hazard lights/switch.

When I start the car, the gear select lights all work fine. Can cycle through all of the gears no problem. When I pull the light switch, the gear select lights all black out. Not dim, but are completely out. All interior lights (dash, headlight indicator, fog light indicator, HVAC, cigarette lighter bulbs don’t function at all. When I push the headlight switch back in, the gear select lights all return back to normal/lit.

Thought it was the switch (dimmer turned down) but that’s
Not it either, but replaced it with a known good unit, still no dash lights or other interior lights. Checked all the fuses associated with dash lights and they all checked out good. Power on both sides of the fuse(s).

Never noticed this problem as I only drove the car in daylight, yesterday was the first “night drive”. Started out fine, stopped to put gas, hit the light switch and no dash lights. Tapped the dash, tapped the console, still nothing.

Haven’t added or removed anything that would cause the issue. Used the ETM, but at a complete loss as to what is causing the issue or where to look.

Any help or advise would be appreciated.

Mahalo’z.
Last edited by KINGJOHN808 on Wed Dec 21, 2022 12:59 pm, edited 1 time in total.
Ewa Kai, Hawai’i
1984 633CSi
1983 633CSi (wreckers)

“Aloha and have a great day!”
KINGJOHN808
Posts: 127
Joined: Sat Feb 16, 2019 2:27 am
Location: Ewa Kai

Re: Dash lights not working

Post by KINGJOHN808 »

KINGJOHN808 wrote: Sat Dec 17, 2022 4:18 am Aloha all. Searched using the “search” feature but could come up with a definitive answer.

My dash lights stopped working/don’t work, to include cigarette lighter bulb, HVAC bulbs, headlight “ON” indicator lights, fog lights “ON” indicator lights etc. the headlights, tail lights, fog lights all function as they should to include the hazard lights/switch.

When I start the car, the gear select lights all work fine. Can cycle through all of the gears no problem. When I pull the light switch, the gear select lights all black out. Not dim, but are completely out. All interior lights (dash, headlight indicator, fog light indicator, HVAC, cigarette lighter bulbs don’t function at all. When I push the headlight switch back in, the gear select lights all return back to normal/lit.

Thought it was the switch (dimmer turned down) but that’s
Not it either, but replaced it with a known good unit, still no dash lights or other interior lights. Checked all the fuses associated with dash lights and they all checked out good. Power on both sides of the fuse(s).

Never noticed this problem as I only drove the car in daylight, yesterday was the first “night drive”. Started out fine, stopped to put gas, hit the light switch and no dash lights. Tapped the dash, tapped the console, still nothing.

Haven’t added or removed anything that would cause the issue. Used the ETM, but at a complete loss as to what is causing the issue or where to look.

Any help or advise would be appreciated.

Mahalo’z.
Aloha all,

Have a update. Using the ETM, checked power going to the passenger side vanity/visor mirror. Have 12vdc. Checked power coming out of “headlight switch lamp” (wire color code GY/RD), have 12vdc. Checked the other wire (wire color code BR/WT), to the same socket and have 12vdc. Removed the bulb from the socket and both sides (GY/RD and BR/WT) still show 12vdc. Looking at the ETM, it continues to reference “Solid State” with regards to the dash lights, OBC and the OBC Computer Panel.

The OBC Computer is functional (time, temp, etc), however it doesn’t light up either, BUT has 12vdc at the socket as well?? Now I’m completely lost.

Per the ETM, the “headlight switch” and the “transmissions range display” both have diodes. Possible that one or more of them have failed and is causing the problem with 12vdc on both sides of the socket ONLY when the headlight switch is pulled?

At a total loss at this point. Any info or suggestions would be greatly appreciated.

Mahalo’z.
Attachments
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5F0E9498-A127-4070-A130-BFAB1CE117D6.jpeg (995.4 KiB) Viewed 1532 times
Ewa Kai, Hawai’i
1984 633CSi
1983 633CSi (wreckers)

“Aloha and have a great day!”
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86_6series
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Re: Dash lights not working

Post by 86_6series »

Definitely a head scratcher.
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RossDinan6
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Re: Dash lights not working

Post by RossDinan6 »

Your having lost all the lights points to a ground issue. In your attachments the common point is the ground, through the light switch dimmer. A bad dimmer or lost ground is where I'd be looking. I know you said you replaced the switch with a "known good" one, but is the variable resistor inside actually good?

Good luck.
Ross
'84 633 Dinan turbo
KINGJOHN808
Posts: 127
Joined: Sat Feb 16, 2019 2:27 am
Location: Ewa Kai

Re: Dash lights not working (SOLVED)

Post by KINGJOHN808 »

RossDinan6 wrote: Sun Dec 18, 2022 9:45 pm Your having lost all the lights points to a ground issue. In your attachments the common point is the ground, through the light switch dimmer. A bad dimmer or lost ground is where I'd be looking. I know you said you replaced the switch with a "known good" one, but is the variable resistor inside actually good?

Good luck.
Aloha Ross,

You hit it right on the head. My known “good unit”
Was just a spare that I removed from another car (37 years old). It worked, but was intermittent (the dimmer circuit/wire loop/spring) had debri inside causing the light switch to be “touchy”. I checked all the ground and everything kept pointing back to the switch, decided to take apart the original switch.

Was all corroded on the inside and holding the board up to the lights I could see where two of the tracks were corroded and making contact with each other. Gave them a good cleaning, plugged it back in and “BAM”. Got all the lights working again to include the shift indicator.

Now I have a working original and a “KNOWN” good spare for test purposes. 🤣

Have provided some pics for anyone that may be having a similar issue. Way cheaper to fix the switch (if possible), then to replace with a brand new unit.

Mahalo’z again. Merry Christmas to you and yours.
Attachments
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Ewa Kai, Hawai’i
1984 633CSi
1983 633CSi (wreckers)

“Aloha and have a great day!”
TimU
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Location: Sydney

Re: Dash lights not working (SOLVED)

Post by TimU »

Well done! Always tricky to troubleshoot an issue when your "good unit" is also faulty.

Happy night-driving!
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RossDinan6
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Re: Dash lights not working (SOLVED)

Post by RossDinan6 »

I'm happy to have been of some help. That board was pretty ugly. I never mind an easy fix, especially when I'm on the clock. :D
Ross
'84 633 Dinan turbo
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sansouci
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Re: Dash lights not working (SOLVED)

Post by sansouci »

How did you clean the board?
Sansouci
84 E24 633Csi Auto, Bronzit/PearlBeige 6997510
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KINGJOHN808
Posts: 127
Joined: Sat Feb 16, 2019 2:27 am
Location: Ewa Kai

Re: Dash lights not working (SOLVED)

Post by KINGJOHN808 »

sansouci wrote: Thu Dec 22, 2022 1:44 am How did you clean the board?
Soft bristle tooth brush to get the corrosion off the board. Then used a pencil eraser on the tracks. Cleaned up really nice but forgot to take a picture before I put it back together.
Ewa Kai, Hawai’i
1984 633CSi
1983 633CSi (wreckers)

“Aloha and have a great day!”
emac
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Joined: Thu Feb 06, 2020 2:57 am
Location: SC

Re: Dash lights not working (SOLVED)

Post by emac »

love a happy ending! That board was really corroded.
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