Light Dimming Issue

[CRW-FK5]

I've been having an electrical problem with my lights for a while now and am trying to figure out what the cause might be.  When my headlights are on and I press on the brakes the radio cuts out and dash lights dim significantly.  If I then rev. the engine (with lights on and brake pedal pressed) the radio comes back on clear and the dash lights return to normal brightness.  With headlights off I do not have any issues with radio.  I have a hot wire running from radio directly to battery (fused).  I realize there will be some dimming of the lights when idling, but this is much more than it should be and the radio should not be affected.  Could I have a poor ground somewhere?  

Below are pics of the ammeter under the following conditions, all while engine is idling.  Do these gauge readings look correct for the listed conditions?

Pic 1)  Lights off / brake not applied
Pic 2)  Parking lights on / brake not applied
Pic 3)  Headlights on / brake not applied
Pic 4)  Lights off / brake applied
Pic 5)  Parking lights on / brake applied
Pic 6)  Headlights on / brake applied

[CRW-FK5]

.

[A383Wing]

Looks normal to me...did you check your grounds?? Maybe add a couple more grounds from engine to firewall.....you should have main battery cable to engine block, and then another 10ga wire from battery to body or rad support

One more thing...what is the diameter of the alternator pulley? They make 3-4 different sizes....I am running the smallest diameter pulley on my car which I think is 2.5" in diameter

[charger Downunder]

Couple of things to check.

Clean the bulkhead connections gently pry it apart.

Check out the long thin plug at the steering column under the dash, i bet it has a brown burn mark on the plug. If so pull it apart and clean and bypass the burnt one.

[b5blue]

Low Alt. idle output. Very common problem. I switched to a Denso alt. but there are many newer options to get more idle output.

[CRW-FK5]

Looks normal to me...did you check your grounds?? Maybe add a couple more grounds from engine to firewall.....you should have main battery cable to engine block, and then another 10ga wire from battery to body or rad support

One more thing...what is the diameter of the alternator pulley? They make 3-4 different sizes....I am running the smallest diameter pulley on my car which I think is 2.5" in diameter

Thanks.  Will check grounding and try adding one to see if that makes any difference.  Checked my pulley diameter and outside dia. is 2.68", about what yours is.

[CRW-FK5]

Couple of things to check.

Clean the bulkhead connections gently pry it apart.

Check out the long thin plug at the steering column under the dash, i bet it has a brown burn mark on the plug. If so pull it apart and clean and bypass the burnt one.

Good idea.  I will check that out.  Thank you.

[CRW-FK5]

Low Alt. idle output. Very common problem. I switched to a Denso alt. but there are many newer options to get more idle output.

Thanks.  I'll check the Denso, as it may be what I ultimately need.  When you say "many newer options" I assume you're referring to other alternators besides Denso, right?

[b5blue]

Yes much better, mine needed a set of brackets to adapt and looks nothing like stock. Now they make much nicer that bolt to factory brackets.

[68 RT]

Feel your headlight switch, is it getting hot? Did you check all lighting connections? Could be corroded?

[CRW-FK5]

Feel your headlight switch, is it getting hot? Did you check all lighting connections? Could be corroded?

Connections were remarkably clean with no signs of getting too hot (no melted plastic signs).  I have not checked the heat from the headlight switch.  I imagine it should be emitting some amount of heat.  Is hot to the touch okay or not?

[charger Downunder]

Have you managed to have a look at the two long thin wire plugs at the steering column under the dash yet. Look for a brown burn mark on the plug. If so pull it apart and clean and bypass the burnt one.

[PlainfieldCharger]

Do a voltage test on the battery. It should read close to 12.7 on a charged battery. Turn on some accessory's and measure voltage drop at the battery.  Start the car check voltage at battery while running. Should be just a little over 14 volts. If not, increase the idle to see if the voltage increases. If not loose alt belt, bad voltage regulator, bad alternator. Turn on the same accessory's and check your reading. You should see an initial drop but go  back to 14v. The system should be able to produce 14 volts and amperage needed to handle the lights at 1000 rpm...

[CRW-FK5]

Have you managed to have a look at the two long thin wire plugs at the steering column under the dash yet. Look for a brown burn mark on the plug. If so pull it apart and clean and bypass the burnt one.

Yes.  There were no burn marks at all.  Connections looks very good.

[poppa]

Not everyone wants to but , I did a relay set up so my headlights run right off the alt (or you could go direct to bat). We'd be out in the boonies and it would get dark before we went home , I'd come to a stop sign with the head lights , brakes and turn signals on and I thought there was a hamster in the head lights holding a birthday candle. Sucked!

Found this a few posts down. Similar to what I did.

http://www.dodgecharger.com/forum/index.php/topic,168.0.html

[CRW-FK5]

Not everyone wants to but , I did a relay set up so my headlights run right off the alt (or you could go direct to bat). We'd be out in the boonies and it would get dark before we went home , I'd come to a stop sign with the head lights , brakes and turn signals on and I thought there was a hamster in the head lights holding a birthday candle. Sucked!

Found this a few posts down. Similar to what I did.

http://www.dodgecharger.com/forum/index.php/topic,168.0.html

Yeah.  I am considering that.  About a week ago the alternator went out in my car and I just had it rebuilt to an 80 amp, so I am planning on seeing how that handles the lights/brake/stereo at the same time while idling situation.  I believe I may still have the dimming issue but want to evaluate any changes first.  Sounds like it may have taken care of it well for you.  My other concern is maintaining stock look, hiding the relays successfully somewhere (under battery tray).  Plus not wild about cutting factory wires.  We will see.  Thanks for the link.

[Nacho-RT74]

I hidden the headlights relay down the dashframe. Headlights source are leaving the cab already "relayed". The headlights are actually on back of the kick panel. Didn't cut any wire. Used the existant one comming out from floor dimmer switch ( violet and red ) to the relay output to run up to  headlights/bulkhead, then replaced the trigger source between floor switch and relay with a same color one. Made the same for the A/C blower sources.

[CRW-FK5]

I hidden the headlights relay down the dashframe. Headlights source are leaving the cab already "relayed". The headlights are actually on back of the kick panel. Didn't cut any wire. Used the existant one comming out from floor dimmer switch ( violet and red ) to the relay output to run up to  headlights/bulkhead, then replaced the trigger source between floor switch and relay with a same color one. Made the same for the A/C blower sources.

So benefit to this approach is concealing the relays and not having to cut the wires, correct?  I am not completely following the wiring you described as related to the floor (dimmer) switch.  How is that tied into the circuit?  Do you have a schematic for this drawn up?  Thanks.

[CRW-FK5]

Just had my alternator rebuilt to 80 amps.  Noticed significant improvements in charging at idle and no longer getting radio cutting out when lights on, brake pressed, stereo on.  Below are my new gauge readings (all with stereo on).  Compare against pictures in initial post.

Pic 1)  Headlights off / brake not applied
Pic 2)  Parking lights on / brake not applied
Pic 3)  Headlights on / brake not applied
Pic 4)  Headlights off / brake applied
Pic 5)  Parking lights on / brake applied
Pic 6)  Headlights on / brake applied

[CRW-FK5]

More

[Nacho-RT74]

Wil explaim later with diagrams detail the headlight upgrade into the cab.

About the amm readings. i guess batt can be slightly discharged yet. A fully charged batt will never give you a charge reading, no matter what you have turned on, so you should get your ammeter going to center after a few minutes, depending on you batt charge conditions.

EXCEPT if you have something being sourced from batt post, which will give you a "ghosty" charge reading, where will be really sourcing whichever is conected to batt post ( or starter relay stud )

What is true is once you get your batt charged, you can turn on mostly of your equipment and will get a small "flick" to discharge, then quickly going to center

[A383Wing]

your readings would have been much better if you would have had the smallest pulley put on the alternator when you had it rebuilt.....smaller pulley will make it spin faster and charge faster...i have the smallest pulleys on all my alternators and it works great

[CRW-FK5]

your readings would have been much better if you would have had the smallest pulley put on the alternator when you had it rebuilt.....smaller pulley will make it spin faster and charge faster...i have the smallest pulleys on all my alternators and it works great

What dia. is the smallest?

[Nacho-RT74]

The best reading posible is 0.

[A383Wing]

your readings would have been much better if you would have had the smallest pulley put on the alternator when you had it rebuilt.....smaller pulley will make it spin faster and charge faster...i have the smallest pulleys on all my alternators and it works great

What dia. is the smallest?

2-1/2" overall outside diameter, available in single or double belt style