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EFV-8 Club Forum / 1940 Ford Discussion / Dim instrument panel lights

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Posted By Discussion Topic: Dim instrument panel lights -- page: 1 2     Carcheologist 04-19-2022 @ 5:23 PM reply profile send p.m. New Member Posts: 128 Joined: Jan 2016 Working on dim instrument panel/dash lights. I tried replacing the rheostat dimmer with a used one I had thinking the old one may have been creating high resistance causing dim lights. The replacement one only helped slightly - dash lights are still very dim. Would a new one help eliminate the problem? While I'm at it, would it be a good idea to replace the foot dimmer switch too? kubes40 04-19-2022 @ 5:39 PM reply profile send p.m. Senior Posts: 3374 Joined: Oct 2009 Bulbs are very low lumens. Try "jumping" the terminals at the rheostat and see if that helps. If it does, you know the rheostat is not doing its best "work". Dimmer switch on floor won't effect the instrument panel lamps. Mike "Kube" Kubarth Carcheologist 04-19-2022 @ 5:49 PM reply profile send p.m. New Member Posts: 128 Joined: Jan 2016 Thanks Kube, I'll try that approach. I agree that the foot dimmer won't help dash lights, but thought it might improve overall lighting performance - my headlights seem a little dim too. A while back, I replaced the headlight switch after I read that they go bad over time and create high resistance and cause dim headlights. What are your thoughts on that? RAK402 04-19-2022 @ 10:49 PM reply profile send p.m. Member Posts: 430 Joined: Jul 2015 I went through my instrument cluster a while back (the Voltmeter was reading way low-replaced with an NOS unit). One of the things I wanted to address was the dim lights. The first thing was to clean the glass-that was quite dirty inside having last been apart in 1976. The interior of the cluster was painted a flat white at the factory (to reflect the light of the bulbs, I suspect). I covered the white areas with aluminum tape. I also covered the back side of the plastic bezel with the same aluminum tape. I try to be a purist when it comes to this car, but I am 47 years older than I was when I first got it (my eyesight was a lot better back then). I went ahead and did these things (which cannot be seen when looking at the panel) which actually worked. My panel lights are now nice and bright. This is with a stock, 6 Volt system. This message was edited by RAK402 on 4-19-22 @ 10:50 PM Carcheologist 04-20-2022 @ 6:45 AM reply profile send p.m. New Member Posts: 128 Joined: Jan 2016 RAK402, Thanks for chiming in with your observations. You mentioned your Voltmeter; I assume you mean the Battery gauge? ( I suppose that it IS a voltmeter!) My battery gauge seems to be working fine. I appreciate your suggestions. 1931 Flamingo 04-20-2022 @ 6:54 AM reply profile send p.m. Member Posts: 383 Joined: Nov 2019 For headlights, make sure you have good grounds or add another. You could change the bulb size for the dash. Paul in CT Carcheologist 04-20-2022 @ 7:05 AM reply profile send p.m. New Member Posts: 128 Joined: Jan 2016 1931Flamingo, Yes, I did check the ground connections for the headlights and they seem to be fine. A while back, I installed a new headlight switch and added a relay. I'll check everything again to make sure. Seems like I read somewhere that an old, worn foot dimmer switch can cause dim headlights too. Know anything about that? TomO 04-20-2022 @ 7:38 AM reply profile send p.m. Senior Posts: 7244 Joined: Oct 2009 The dimmer switch is the first place that I look when troubleshooting dim lights. The sealed beams need at least 6.0V at the bulb to reach a normal brightness. The way that I troubleshoot dim headlights is use a voltage drop test to find the points of resistance. Connect the black or COM lead of yoiur meter to the NEG post of the battery and the red or + lead to the headlight socket wire for the right hand headlight. Turn on the head lights. The meter should read 0.5V or less. Turn off the lights. If it is more than 0.4V move the red lead to the dimmer switch terminal for the low beams and turn the lights on. The reading should be less than 0.3V. If the reading is higher move the red lead to the input to the dimmer switch. the reading should now be 0.2V or less. Continue this process back to the input of the light switch where the meter reading should be less than 0.1V If the reading is less than 0.4V, move the red lead to the POS post of the battery and the black lead to the grounding wire on the headlight plug. Turn on the lights. The reading should be 0.1V or less. If it is higher check your grounding straps for corrosion or replace them. The stock dash light bulbs are no.51 bulbs, you can replace them with no. 55 bulbs. RAK402 has the right idea about having a clean glass over the instruments and having a good reflective surface for the light to direct the light. Tom bo8109b 04-20-2022 @ 9:48 AM reply profile send p.m. New Member Posts: 179 Joined: Nov 2009 Years ago, I changed my '40 instrument bulbs to 6V LED bulbs which really brightend things up. May still be available on Amazon. Carcheologist 04-20-2022 @ 10:42 AM reply profile send p.m. New Member Posts: 128 Joined: Jan 2016 TomO, Thanks for your in-depth troubleshooting instructions. Please forgive me, I'm somewhat "electrically challenged" sometimes. Do I set the test meter on Volts or Ohms? And, am I correct in understanding you are speaking of only a fraction of a volt (0.4 volts), etc. when measuring with the test meter? I thought I would expect to see higher voltage at the headlamp socket. Sorry if I'm a little slow and appreciate your clarification.

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