H4 Headlights cause voltage drop?

vamram · Posted: Wed Dec 17, 2014 9:48 am Post subject:

Ashman, thanks for that great explanation. I believe this is the route i'll be going, new wire direct to the lights thru dedicated relays.

Mr. Duncan - is there a good way to fish the wire from the battery to the front? Through the heater channel? Or under the headliner across the roof? What do you use to do this?

Thanks!

Victor
_________________
Eventually, "we are what we pretend to be.’”
Give peace a chance - Stop Russian-Soviet Aggression!!

'74 Super 9/16 - present, in refurb process.
'73 Super - 6/18 - Present - Daily Driver!
'75 Super Le Grande...waiting it's turn in line behind '74.
Click to view image
Save the Supers!!

Mr.Duncan · Posted: Wed Dec 17, 2014 9:49 am Post subject:

I run wires next to the factory harness, and use fishtape, or a thin, yet strong metal wire to push/pull the wire through tight spots.
_________________
(Owner) www.vintagecarleds.com

Red 1971 Squareback Thread
Red 1966 Beetle Thread
---------------------------------------------------
1971 Green Super Beetle (sold)
1966 Ghia (sold)
1971 Blue Super Beetle (sold)
1966 Java Green Std Beetle (sold)
1971 Red Squareback (sold)
1966 Red Beetle

vamram · Posted: Wed Dec 17, 2014 10:26 am Post subject:

Ashman, I used fine sandpaper to clean the grounds and the fuse terminals on the inside of the car. I still have to do the same to the trunk-side fuse box connections. I'm also going to run a new wire from the alternator to the starter.

If I still get the drop after the cleaning and new alternator wire, i'll cut the last inch of the headlight wires and recrimp them per Aircooled's suggestion. If all of that combined doesn't fix it, THEN i'll go w/the 8gw wire from the battery to a fuse terminal like the one TX-73 pictured, and new wires from there to the lights w/the relay kits Mr. Duncan suggested using.
_________________
Eventually, "we are what we pretend to be.’”
Give peace a chance - Stop Russian-Soviet Aggression!!

'74 Super 9/16 - present, in refurb process.
'73 Super - 6/18 - Present - Daily Driver!
'75 Super Le Grande...waiting it's turn in line behind '74.
Click to view image
Save the Supers!!

ashman40 · Posted: Thu Dec 18, 2014 7:25 am Post subject:

Did you confirm where your dash voltmeter is connected?
It could be connected to the black (#15) ignition circuit or it could be on the black/yellow (X) accessories circuit that powers the headlights. Knowing which may make a difference in understanding why the voltage drops.
As described above, if the voltmeter is connected to the X circuit it will be sharing the current flow of the X circuit which also powers the headlights. When you turn the headlights ON your reduce the current/voltage available to power the voltmeter.

Also, I'm not sure I would trust the dash voltmeter over a good multimeter.
Compare the voltmeter readings with your multimeter.

Try this test...

Compare your results. As you move the load of the headlights further away from the X circuit and the #15 ignition circuit you should see the voltage at your voltmeter improve.
If there is little difference when powering the headlights from the #30 circuit (Test-C) and directly from the battery (Test-D) then you DON'T need to run a new wire from the battery, just tap the power to your new relays from the #8 input side of the fuse box.

I hope this is clear? The above tests illustrate the benefits of powering the headlight relays from different points along the electrical system.
_________________
AshMan40
---------------------------
'67 Beetle #1 {project car that never made it to the road Sad

}
'75 Beetle 1200LS (RHD Japan model) {junked due to frame rot}
'67 Beetle #2 {2019 project car - Wish me luck!}

vamram · Posted: Thu Dec 18, 2014 8:20 am Post subject:

Dexter, thanks for that detailed test plan. I'll be able to do tests A and B today, but may have to wait on C and D until Dec. 28. I'm getting some holiday travel in beginning later today w/la mia famiglia until then.

I'll post back what I get w/the tests i'm able to do today. In the meantime, Happy Holidays/Christmas/Hanukah/etc to TheSamba!

Blue Bug

_________________
Eventually, "we are what we pretend to be.’”
Give peace a chance - Stop Russian-Soviet Aggression!!

'74 Super 9/16 - present, in refurb process.
'73 Super - 6/18 - Present - Daily Driver!
'75 Super Le Grande...waiting it's turn in line behind '74.
Click to view image
Save the Supers!!

vamram · Posted: Thu Dec 18, 2014 10:51 am Post subject:

Ashman, here's what I was able to test before having to stop to pack my bags.

TEST A - IGNITION OFF//IGNITION ON
# 8 - 12.4+-// 11.8
# 10 - 0 // 11.83
# 12 - 0 // 11.82

Battery posts: didn't get to this.

TEST B - LIGHTS ON (Low beams only - the relay switched back to low and wouldn't go to Hi)
IGNITION OFF/IGNITION ON
#8 - 12.4/ 11.2
#10 - 0 / 10.7
#12 - 0 / 10.6

TEST C - Fuse 8 Removed
- 12.2v on the INPUT side - closer to the pedals
- jumpering it w/5 & 6 turns on the lights. Hi beams are #6
- I couldn't test voltage w/the jumper wire on because I don't have ends that can clip on those at the moment.

*ALSO*: You didn't ask me to test Fuse #9, but this one also has 12.2v on the INPUT side w/the ignition off. Should it be reading 0 volts?

I'll have to try the other parts of TEST C and the battery check when I return. And I ran out of time to trace the power wire for the VDO voltage gauge. I can tell you that it and the oil temp and pressure gauges appear to be powered in a daisy chain.

I will be on thesamba while on vacation so i'll check for any observations you or others may have using the partial test results.

Thanks again!

Victor
_________________
Eventually, "we are what we pretend to be.’”
Give peace a chance - Stop Russian-Soviet Aggression!!

'74 Super 9/16 - present, in refurb process.
'73 Super - 6/18 - Present - Daily Driver!
'75 Super Le Grande...waiting it's turn in line behind '74.
Click to view image
Save the Supers!!

Mr.Duncan · Posted: Thu Dec 18, 2014 10:57 am Post subject:

When you say "ignition on" do you mean, motor is running?

If so:

looks like you have a charging problem.
_________________
(Owner) www.vintagecarleds.com

Red 1971 Squareback Thread
Red 1966 Beetle Thread
---------------------------------------------------
1971 Green Super Beetle (sold)
1966 Ghia (sold)
1971 Blue Super Beetle (sold)
1966 Java Green Std Beetle (sold)
1971 Red Squareback (sold)
1966 Red Beetle

vamram · Posted: Thu Dec 18, 2014 11:06 am Post subject:

Duncan, ignition on is w the motor off. That's what I thought Ashman meant. Question

_________________
Eventually, "we are what we pretend to be.’”
Give peace a chance - Stop Russian-Soviet Aggression!!

'74 Super 9/16 - present, in refurb process.
'73 Super - 6/18 - Present - Daily Driver!
'75 Super Le Grande...waiting it's turn in line behind '74.
Click to view image
Save the Supers!!

ashman40 · Posted: Fri Dec 19, 2014 4:36 am Post subject:

vamram · Posted: Fri Dec 19, 2014 9:10 am Post subject:

Ashman, thanks for the analysis. I think you're right about the battery. It's two years old. The car was hard to start after it sat for 3 weeks waiting for body work and parts in November. I have a charge and will hook it up when I return.

Also, my older brother is an electrical engineer and agrees w/Aircooled that the original ends of the 42 year old harness are probably corroded, causing high resistance and recommends replacing the ends. He also recommends testing the lights one side at a time by disconnecting the headlights at the lamp, one first then the other.

Thanks!

Victor
_________________
Eventually, "we are what we pretend to be.’”
Give peace a chance - Stop Russian-Soviet Aggression!!

'74 Super 9/16 - present, in refurb process.
'73 Super - 6/18 - Present - Daily Driver!
'75 Super Le Grande...waiting it's turn in line behind '74.
Click to view image
Save the Supers!!

[email protected] · Posted: Fri Dec 19, 2014 11:38 am Post subject:

Just pointing out that each wire has 2 ends. I know it's obvious in reflection, but don't want to see only half the problem addressed.l
_________________
It's just advice, do whatever you want with it!

Please do NOT send me Private Messages through the Samba PM System (I will not see them). Send me an e-mail to john at aircooled dot net

"Like" our Facebook page at
http://www.facebook.com/vwpartsaircoolednet
and get a 5% off code for use on one order for VW Parts ON OUR PARTS STORE WEBSITE, vwparts.aircooled.net

ashman40 · Posted: Fri Dec 19, 2014 8:00 pm Post subject:

Here is an example of why you need to cut away the ends of the wires to reach clean conductors:

Image may have been reduced in size. Click image to view fullscreen.

Found this neat trick to acid etch the ends of old wires to clean them up. A bit tedious if you have lots of wires to do, but if you really can't afford to cut the length of the wire, then thorough cleaning is an alternative.
http://www.instructables.com/id/How-to-perfectly-clean-wires-in-minutes/
_________________
AshMan40
---------------------------
'67 Beetle #1 {project car that never made it to the road Sad

}
'75 Beetle 1200LS (RHD Japan model) {junked due to frame rot}
'67 Beetle #2 {2019 project car - Wish me luck!}

MacLeod Willy · Posted: Fri Dec 19, 2014 8:27 pm Post subject: trick

That trick is going right in my back pocket. Thanks!

Aussiebug · Posted: Sat Dec 20, 2014 12:03 am Post subject:

Ashman - I'd forgotten that trick from my valve radio days - it's back in the memory banks now. Thanks for the post.
_________________
Rob
Rob and Dave's aircooled VW pages
Repairs and maintenance for the home mechanic
http://www.vw-resource.com

rockerarm · Posted: Sat Dec 20, 2014 3:47 pm Post subject:

Hello all. Just saw this 4 page post and had to reply. It seems to me that not too many folks really know how to do a proper "voltage drop test". Properly used the DVOM will "do the math" and easily tell you what the voltage drop is. The main advantage to this "voltage drop test" is that it tests the circuit under load, as a treadmill would test a human being's various functions.

Try this. Access the back of both headlights. You have to use a digital DVOM (digital volt meter). Using your DVOM, hook the positive lead to the positive battery terminal and the negative lead to the back of one of your headlight. You will probably need to use a jumper lead to do this. Turn your headlights on and you can measure the "voltage drop" between the voltage source (battery) and the component (headlight). This will be the TOTAL VOLTAGE DROP from the battery to the headlight. You can check both low and high beam circuits individually. You can also check a ground circuit in the same manner. If a problem exists then you can expand the voltage drop test to individual circuits, IE: you can simply use this test across a fuse for the headlight.

PLEASE, go to you tube and type in voltage drop test and watch the show.

I hope this helps, Bill.

vamram · Posted: Sat Dec 27, 2014 6:10 pm Post subject:

I watched a couple of the youtube videos, good stuff for me. So i have several places to check for resistance.

Arrived back home today and had time to change the relay I thought was bad because the headlights wouldn't switch between hi/low beam, but get stuck at one or the other.

Turns out it's not the relay. Even w/the new relay, i can't toggle between hi/lo beams. Currently it's stuck at hi. So I guess in addition to resolving the weak battery and the voltage drop, now I've got a possibly bad turn signal switch. Sad

And tomorrow's forecast is 40s w/80% chance of rain. Sheesh. Mad

_________________
Eventually, "we are what we pretend to be.’”
Give peace a chance - Stop Russian-Soviet Aggression!!

'74 Super 9/16 - present, in refurb process.
'73 Super - 6/18 - Present - Daily Driver!
'75 Super Le Grande...waiting it's turn in line behind '74.
Click to view image
Save the Supers!!

ashman40 · Posted: Sat Dec 27, 2014 9:49 pm Post subject:

vamram · Posted: Sun Dec 28, 2014 8:37 am Post subject:

Thanks Ashman. Is the dimmer switch in the turn signal assembly or is it the switch in the dash that I pull to turn on the lights?

I'll try to rig up a jumper wire test today and report back.

I bought this relay from Pierside parts: http://www.piersideparts.net/111941583.html

Although it looks like the original silver swf relay, it's actually black and a bit heavier. It's 5-prongs.

Thanks,

Victor
_________________
Eventually, "we are what we pretend to be.’”
Give peace a chance - Stop Russian-Soviet Aggression!!

'74 Super 9/16 - present, in refurb process.
'73 Super - 6/18 - Present - Daily Driver!
'75 Super Le Grande...waiting it's turn in line behind '74.
Click to view image
Save the Supers!!

Blue69Baja · Posted: Sun Dec 28, 2014 8:59 am Post subject:

Test B procedure has a problem with Ignition on!

One will get inconsistent readings when turning on the ignition.

Why? If the points are closed you will get about an additional 3-4 amp extra draw during the test, thus less voltage for the reading. Points open, no drain through the coil, points to ground.

For this test I would either make sure the points are closed or open.... OR disconnect the wire (typically green) to the dizzy.

Jim
_________________
69 Baja with a 1914...
72 Super 100% orig...W/ factory air... 56,000mi
Even the spare is original..

vamram · Posted: Sun Dec 28, 2014 9:46 am Post subject:

Jim - i use a compufire electronic ignition rather than points. Do you recommend disconnecting both of its leads for test B?
_________________
Eventually, "we are what we pretend to be.’”
Give peace a chance - Stop Russian-Soviet Aggression!!

'74 Super 9/16 - present, in refurb process.
'73 Super - 6/18 - Present - Daily Driver!
'75 Super Le Grande...waiting it's turn in line behind '74.
Click to view image
Save the Supers!!


Hello! Log in or Register \| Help \| Donate \| Buy Shirts	See all banner ads \| Advertise on TheSamba.com

H4 Headlights cause voltage drop?
Page: Previous 1, 2, 3, 4, 5, 6, 7, 8, 9 Next

Forum Index -> Beetle - Late Model/Super - 1968-up		Share:
		Print View

	Forum Index -> Beetle - Late Model/Super - 1968-up	All times are Mountain Standard Time/Pacific Daylight Savings Time Page: Previous 1, 2, 3, 4, 5, 6, 7, 8, 9 Next
Page 4 of 9