Dash lights that dim

-
J

JamesH

Member
Joined
Sep 4, 2010
Messages
16
Reaction score
0
Location
FL
I'm having a problem with my dash lights, they dim when I'm at a stop and increase in brightness when accelerating. My ampmeter / gauge will peg charging while accelerating and return to the middle of the gauge when at idle. My set-up; 68 Barracuda with a Indy Stroker small block, using a MSD distributor and 6AL ignition box with a MSD coil, the stock altenator was rebuilt and stepped up to 75 amps, I also have a Be-Cool radiator with two electric fans. The stock voltage regulator is still in place along with a stock replacement ballist resistor. I also noticed that my after market radio also powers off and on at idle.
Any thoughts on this problem would be a great help.
Thanks.
 
where did you tie into the radio at? depending on where you spliced in at. Also what kind of headlights do you have?
 
There was a thread about this a week ago I think. Put LEDs in it
 
in my opinion its sounds like your getting alot of voltage drop at idle. probably just your typical old dirty corroded connections. it all adds up. a rusty connection here, a dirty connector there. if you plan on keeping your car and driving it a lot, i would suggest an aftermarket wiring harness. i dont like the design of the mopar harness. i think some of the wires are too small. especially if you are going to add accesories and especially if you went to a 75 amp alternator. i hope you went to larger wire to your amp gauge. another upgrade you may want to look into is running you headlights through relays. just like you would do with an electric fan. this way your headlight switch is only turning the relay on and off and the power for your headlights is coming straight off the battery. this way they get full voltage instead of the voltage thats left after it has to travel inside the car to the switch and then back out to the headlights through probably a 16 gauge wire. if you have any questions let me know. i will help ya out.
 
slantscamp sounds right on the money. I had that problem and relayed the headlights and it stopped. the relays can be bought at pepboys for like $12 a pop. Or you can goto the junkyard, then you can get the connectors as well. easy as pie to put on. Also you can get LED's for the lights in your dash. they are MUCH brighter and you can get different colors that can go with your interior color
 
As to the tie in for the radio, I just used the lead from the old radio. Don't know about running a bigger gauge wire from the alt to the amp. I just stepped up the alt for the elec. fans. The rest of the wire harness is stock. I think that the headlights are fine when I'm at a stop. I haven't noticed any change when driving. What after market wire harness is best? Where do I install the relays to the headlights? The headlights are stock, no LED or High Discharge.
Thanks for everybody's help.
 
I had super dim dash-lights also. What I did to fix it was get a new headlight switch and new lamp sockets. The dimmer circuit uses an old style rheostat to alter the resistance of the circuit. Its that coil wire mounted in that white ceramic disk in the headlight switch. The coil wire heat up, they corrode over time, and if the mounting is deteriorating the resistance on that coil gets way to high resulting in super dim dash-lights.
In my opinion, unless you really want LED dash lights, or enjoy making new circuits, the best and easy fix is to get a new light switch.

For you old timers like me, it works exactly the same way as the throttle guns on the old AFX slot-car race tracks. Remember that special ozone smell they made as they heated up?

Anyway, I got my switch, BWD Headlight Switch, at advanced auto for $16.99. Its pretty much NOS. I also replaced all the light sockets on the cluster since they are plastic and that gets brittle after 37 years. I found those at Rockauto. And they are sold two to a package. Thats important to remember or else you will end up with twice the number you needed, like me. Now the cluster lights work as good as new.

Hope it helps. It should save time and aggravation.
 
I think the real problem you have is that you're pulling too much current at idle than the alternator is capable of providing. Assuming your system output voltage is correct and your alternator is working properly you may try increasing your idle speed, change to a smaller alternator pulley or just turn things off when idling.
 
Alternator output is only one piece of the puzzle. it's rpm may be too low at idle but I doubt that's the case.
Electrical connections are most likely your problem and this problem likely existed before any of your mods.
Check bulkhead connections, ignition switch connections, chassis ground connections, and amp gauge connections.
 
You must log in or register to reply here.
-

Back
Top