Everything Dims!!!

[TomoHawk]

Why not just increase your idle RPM?

It looks like the voltage you measured was ground, which should be zero, but a DMM will show a few mV. Touch the black prode to the engine and the red one to the battery + terminal, then fusible link, etc., to trace the power down to the lamps. You'll see where the resistance is and get the idea that everybody talks about. Try measuring the wire that sends the (+12 Volts) to the lamps at the lamp connector. Not sure what color it is on your car.

Allways have a good wiring diagram, a test light, multimeter, etc. I even have a 12volt buzzer to check stuff I can't reach.

[hls30.com]

Looks like your alternator has more current than my synapses!

You are right about the pulley! Sorry, temporarily brain:dead:

Your engine ground is good too!

Will

[Xargon321]

well just a few things i noted while driving tonight.

at idle with the lights on and my radio on i turned my wipers on and it killed my radio once the wipers completed thier pass my radio came back on, this also happens when i turn my heater fan on as well. once i got home and shut the engine off i left my radio and lights on and when my wiper turned on it killed my radio till the wipers where done.

are there anyother ideas?

anyone know the formula to figure the alt revs to crank rev so i can figure what pulley size id would need if it is that?

[ChrisA]

You might have to experiment with pulley sizing. Take your stock pulley down to the parts house and see if they can get anything smaller by say eighth or quarter inch.

[hls30.com]

1) take the Alternator to AutoZone or any place that will check it for free-it could be the root of this evil.

2) None of us could be that lucky, go throught the battery connections and fuse box with your VOM, check the resistance across each connection. (One lead on a clean area on each side of the connection-just like you checked your engine grounds-but the leads will only be 1/2" apart) When you find a connection with high resistance, take it apart, clean it, put it back together, and check it again. For there to be that much resistantance in your system, the problem is between the battery and the out bound wires at the fuse box.

Will

[sblake01]

Originally posted by ChrisA

You might have to experiment with pulley sizing. Take your stock pulley down to the parts house and see if they can get anything smaller by say eighth or quarter inch.

I'm amazed that this keeps coming up. I don't think pulley size is the answer. My 78 with air, stereo, amp, etc. doesn't do this and it has a stock alternator. The problem has to be elsewhere. You spin that alternator faster than it was designed for and you are asking for premature alternator problems IMHO.

[Xargon321]

Ya im going to have to check the resistance, the alt should be new i bought a new one and a vr cause they where both bad, i get the amp meter to move up when i give it gas, but at idle with the lights on it show that it cant keep up.

The alt it rated to spin 1000-13,500 rev/min i dont think going to a slightly smaller pully will bring it out side that range.

hmm i just thought of somthing else im going to thave to check the part # off the alt they might have given me the 37.5 one insted of the 45 amp one :stupid:

[TomoHawk]

You should read the specs on your alternator when you find the part #. Like an engine, it has a "power band" where it puts out the best, so you would want the pulleys be the right diameter(s) to keep the alternator spinning in that RPM range. Keep in mind the kind of driving you do for pulley selection (street "stop-n-go", highway, racing).

my $.0002.... oops- $.02

[Xargon321]

ok changed out all the fuses, Guess i didnt look at them hard enough :stupid: had a 15a in the left light and a almost rotten fuse in the right, and varies others where to high of fues, i cleaned the fuse holders and replaced the fues and it seems to be a little bit better but its still very noticable

[TomoHawk]

Now do clean all the rest of the connectors, and somehow miraculously cure the wires of corrosion from the inside.

Then tell me how.

[beandip]

Way back you said that you took the batt from a car that had NOT been driven regularly , did you put it on the battery charger??? First off before you can gague this voltage problem you MUST start with a good fully charged batt. The pulley size change is not a good idea unless you only drive slow ! They are sized so that they will generate enough rpm for the alt . or water pump or what ever to spin at a speed to do there job in a normal condition. Now have you looked at the head light bulbs ? Are they seald beams or have they been upgraded to halogen units? They will draw more current. You said that the battery connections were removed from the batt, did they get cleaned of all dirt and crud at that time. Is the surface of the batt clean ? If allowed to become dirty on the top or outside there will be a current loss that can be mesured with a meter there. As was stated before start cleaning ALL connections ,caroded connections will cause resistance and heat in the wireing and failure. When you start the engine DO NOT have any lights on untill the engine is running. After checking what I have just suggested the problem still exists I recommend that you have the electrical systime checked by a professional. :classic:

[beandip]

There is no doubt that there is an abnormal condition that you are experiencing . Especially when you state that the functioning of the wypers cause the radio to stop working . Who installed the radio and where did they get the power supply for it ? Was the wireing cobbed up to do the install? I dont know if this will make a difference in this case, but there should be a ground strap at the rear of the engine to the firewall to ground the block. I doubt that this would cause your problem but it will cut down on static on the radio. Here is a test that you can try . go out and turn on the head lights with the engine off as well as all other electrical items, just the head lights. Now blow the horn and watch the difference in the brightness of the lights. If they dim much at all have the battery checked. Have a load check done not just a meter that shows voltage. You need to see what it shows under load. Then go from there in your quest. 1st do the test 2nd clean all electrical contacts, grounds , all of it. 3rd charge the batt . and do the horn test again . 4th load test. Where I live they sell batteries at the tire shop and can do a load test. and will do it free. Good luck. Gary