Here's something for all you electrical gurus, I've racked my brain and can't figure it out. I have a 47 Chevy with the original wiring that isn't in the greatest shape...but isn't shot. Nothing has been touched and all parts are original, which is great except I have dash lights that don't work, (and a flasher unit that doesn't work but that may be another story.) Here's what I've done: I replaced the bulbs with new correct 6 volt bulbs. Broke out a test light. That shows I have power where I'm supposed to at every terminal on the headlight switch. The high beam indicator, glove box light, and cig. lighter work just fine as do all the other accessories. But when I put the lamps back in their sockets & gauge housings I get nothing. Any idea why the dash lights wouldn't work if I'm getting power at the source and the dash & everything is solid metal ground? Is something not grounded properly? Also the signal flasher don't work and I've tried new a new 6v flasher relay. I get them to flash manually by moving the signal stalk, but it won't trip the flashers like they're supposed to. Bulbs are new, housings are clean and sanded contacts. Could this be related to my other issue? Thanks for whatever help y'all can offer.
No, I was just clipping to the underside of the metal dash. The gauges seem to use the dash & the mouting screws as a ground?
Just test straight across an empty socket...should read 6V if lights are switched on. If not, then go from hot side of socket to a known good ground...if you have it there, the cluster has a bad ground.
I could be reading it wrong.... but if you now "lose" power at a terminal on the H/L switch when you install the bulbs?...then it is a bad connection. Common sense will tell where it is. If only one terminal goes dead, but the H/L switch still has it's feed power, then it would be an internal connection in the switch that is dirty. If it also lost the power "to" the switch, then back trace that feed wire to where it gets power. When testing sockets with just a small load like a test light, a poor connection may show good, but putting a larger load with more bulbs can cause the connection to be completely dead.
Good deal. Insulation on the wires look good, and I believe the lamps are all on one wire and daisy chain off each other. If its dead in one spot or shorting out in one place, the rest in that circuit will be dead, too I assume. This may be what you mean F&J with the larger load, right? I will follow up on the sockets & connections and post results. Thank you everyone!
The most common problem with 6V stuff is Bad grounds. Make sure grounds are clean and tight, if something grouds to chassis, try runing a jumper to a known good ground, as the factory connections may be carroded, then test the appliance. 6V needs good flow all the way through the system, and depends on clean and tight grounds with a good return path to the battery. If you don't have a ground strap from the body to the frame or engine get one. For the purpose of testing stuff mounted to the body, make up a jumper wire of two strands of 10 or 12 gauge wire and some good alligator clips to connect the body in lue of a store bought ground strap. if stuff starts working the get the good ground cable. Make sure you primary battery cables are 0 or better yet 00 gauge gauge cables with soldered on ends. If you can't find those 1 gauge is minimum. You can usually get stuff made at welding shops using welding cable in place of the aught or double aught if you have one near you.
This is good to know. I'm running a new positive cable but using the original braided copper ground strap since it looked like it was in great shape and it cleaned up real nice. Maybe its not enough, and that would make sense. I will look into this area as well. Thanks!
Find a place that can make you up some 2 0 welding cable with ends that you need. A very good investment.
on the dash light problem i would agree about the bad ground. as far as the turn signal switch, it sounds like the bulbs are not enough of a load to trip the flasher. don't use a heavy duty flasher.
Re; flashers,.... Those are made to flash either 2, or 3 bulbs,.. Be sure you have the correct item. That gave me a headache, until someone told me. grounds, grounds, and more grounds.....can't have too may GOOD ones. 4TTRUK
This is a very common problem. The rheostat is the variable resistor that you turn to adjust the brightness of the dash lights. Sometimes when the rheostat is bad you can turn the knob fully counter clockwise and they'll turn on at full brightness. Although the 47 switch might be different...and it might have been changed to something else... http://chevy.oldcarmanualproject.com/shop/1942_47/4247csm1231.htm
we often run into dash light issues. Most of the time, it is bad bulbs or a bad rheostat on the H/L switch. When it is the latter, we just pull full power from the H/L switch to the dash wiring harness. Most of us want the lights as bright as possible anyway, so why mess with the rheostat?
Hook the test light to a good ground and touch it to the back of the gauge housing with the lights on if the test light lites the housing is not grounding.
good grounds are your best friends, been finding that out with my 59 VW. the slightest movement in the wires make the light go out and come back on. good connections and grounds make 6v systems work like they should
UPDATE: True to form, the HAMBer advice pays off. I got my lights working again after a few hours on my day off! Here's proof: It turned out being a bad rheostat on the headlight switch. I missed testing that terminal earlier since my hands were too chubby and I was following the wrong wires. (I aparently need to learn what a natural with black tracer vs crossed black tracer is). I was also being a little too timid with the old wiring and didn't want to move stuff around much. Anyhoo, I made it work by chasing down the wires I needed, and pulling power from the rear parking / stop lamp feed on the headlight switch. I used a nice butt splice connector and heat shrink around the whole package. This should get me down the road again until I get a new switch. Yet another success story thanks to the HAMB crowd, and Folgers coffee. Thanks so much everyone! I've got another project crossed off my list for next spring. I can hear Meatloaf singing about dashboard lights right now
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