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J1 Samba Member
Joined: February 10, 2014 Posts: 698 Location: SoCal
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Posted: Fri May 27, 2016 10:12 am Post subject: Diagnosing dim headlights and dash lights |
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How do I diagnose whether it's a ground problem or just bad bulbs or relay or something else?
My headlights and dash lights are definitely too dim. Other lights all work fine but not sure whether they'd be considered dim since they are colored like the turn signals.
I'm hoping for step by step troubleshooting tips before I spend more time and money. Note: I'm too stupid and lazy to understand electrical stuff. Thanks as always. _________________ 1971 Ghia coupe. Assume I know nothing and you'll be pretty darn close to the truth. |
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swavananda Samba Member
Joined: February 14, 2009 Posts: 889 Location: Can o' Scruz
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Posted: Fri May 27, 2016 12:19 pm Post subject: Re: Diagnosing dim headlights and dash lights |
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http://www.thesamba.com/vw/archives/info/wiring/70-71ghia.jpg
I would first suspect the switch is crapping out. With your volt meter, check out various point of connection to establish where you have the right voltage . 12.5 static, 13+ while running. Start with Battery > Voltage reg. > fuse block > Light switch and then output from switch ,in particular the#56 tab , still good ?,then the dimmer relay ,then head light socket.... where ever the voltage drops is your suspect. But the switch is already a weak link in design, Transferring high amps through a lousy contact . |
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c21darrel Samba Member
Joined: January 22, 2009 Posts: 8206 Location: San Dimas
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kiwighia68 Samba Member
Joined: October 20, 2013 Posts: 2867 Location: Auckland, New Zealand
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Posted: Fri May 27, 2016 1:26 pm Post subject: Re: Diagnosing dim headlights and dash lights |
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c21darrel wrote: |
...As far as the dash lights, you have the switch rotated fully to the right, correct. :wink: :)
Im with you...i hate electrical and im not good at it. :cry: :oops: |
Echo that. Hate it and no good at it. But that's why we have people like swavananda around.
I closed the door on electrics yesterday - after good advice from swavananda - and never want to open it again. (I even thought my dash lights were not working when all it was, was that the switch was not turned all the way to the right, exactly as you say.) _________________ Festina lente - hasten slowly
1968 Ghia named Emiko
Resto completed Dec 2015 |
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swavananda Samba Member
Joined: February 14, 2009 Posts: 889 Location: Can o' Scruz
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Posted: Fri May 27, 2016 2:38 pm Post subject: Re: Diagnosing dim headlights and dash lights |
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Here is a great article and 'Mod' improvement for your headlights circuit , It might give you a headache trying to figure it out though. Basically like I said, The switch is trying to push about 20 amps through a dodgy connection, It only gets worse with age. Solution is to hard wire HI/Lo circuits through relays and use the switch only to trigger the relays. It makes a huge difference and mandatory if you thinking about running higher watt bulbs than 60/55.
http://www.danielsternlighting.com/tech/relays/relays.html |
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Mellow Yellow 74 Samba Member
Joined: October 14, 2014 Posts: 1615 Location: Sydney, Australia
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Posted: Fri May 27, 2016 3:25 pm Post subject: Re: Diagnosing dim headlights and dash lights |
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Jay Brown sells these through the classifieds http://www.thesamba.com/vw/classifieds/detail.php?id=1007337.
They are good quality, good value and he is great to deal with.
They are advertised as for Vanagon but I have installed them on my Bus as well and they work great. I also bought a set for my KG to use once I finish my resto (in about 5 years - lol). Just double check they are the right ones when you order. _________________ 1962 Karmann Ghia
1974 Deluxe Microbus
1985 Caravelle (Vanagon) |
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e&m_ghia Samba Member
Joined: April 04, 2011 Posts: 418 Location: NoVA
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Posted: Fri May 27, 2016 7:49 pm Post subject: Re: Diagnosing dim headlights and dash lights |
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swavananda wrote: |
Here is a great article and 'Mod' improvement for your headlights circuit , It might give you a headache trying to figure it out though. Basically like I said, The switch is trying to push about 20 amps through a dodgy connection, It only gets worse with age. Solution is to hard wire HI/Lo circuits through relays and use the switch only to trigger the relays. It makes a huge difference and mandatory if you thinking about running higher watt bulbs than 60/55.
http://www.danielsternlighting.com/tech/relays/relays.html |
Rule 1: Don't assume that the wiring you have is the wiring in the book. Many of these cars have decades of modifications, and some of the after-market harnesses & things will lead you down the wrong path…
Rule 2: There is no other guide, so you have to start from the book anyway…
swavananda had it right, though. You have to trace out each circuit. The wiring diagrams (e.g., in Bentley guide) are a mess, but they're what we have. So copy or down-load one, enlarge it, trace each circuit from the load (headlight, etc) back to the source with high-lighter, and start measuring voltage drops… Work with just one circuit/wire at a time. Be prepared to be adaptive.
On our Ghia I ended up running almost everything from the large battery wire coming from the back of the car, through relays to the individual circuits. Most of the voltage drop was happening in the ignition switch, and I wasn't looking forward to frying that (Voltage_drop times current equals heat in the switch) so I by-passed most of the current through the relays. Headlights still aren't exactly bright by modern standards, with conventional bulbs, but they're better than they would have been - they get pretty much the full battery/alternator voltage.
I don't actually mind the electrical stuff. But my back can't take leaning over the spaghetti mess of wires left by previous owner, to which I've added, and working on it for any length of time… So we all have our constraints. (I keep on meaning to build a diving-board that will allow me to clean it all up while laying on my stomach. Some time.) |
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runamoc Samba Member
Joined: June 19, 2006 Posts: 5593 Location: 37.5N 77.1W
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Posted: Sat May 28, 2016 6:43 am Post subject: Re: Diagnosing dim headlights and dash lights |
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Easy enough to troubleshoot without buying a lot of un-needed relays to find out that's not the 'cure' to the problem.
Take a jumper cable, like the ones that have two 'alligator' clips. Look for the largest red wire on the fuse panel. That will be wire #30, always 'hot'. Put one end of the jumper cable on that and put the other end of the jumper cable on either the yellow or white headlight wires. You can hook to the individual yellow and white wires on the bottom of the fuses to check individual headlight filaments or to the top of the fuses where there is just one wire, yellow or white to check both low and high beams. If they are still dim, it's not the switch. Really, almost all cases you have described has been because of a bad ground. _________________ Daily driver: '69 Baja owned 44 yrs - Plan B: '81 Rabbit Diesel LS Deluxe - Plan C: '72 Ghia
Yard Art: 2 Sandrails
Outback: '69 Ghia - '68,'69,'70,'72 Beetle - '84 Scirocco, GTI - Pair of '02 Golfs-
VW Wiring = It's just wires |
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J1 Samba Member
Joined: February 10, 2014 Posts: 698 Location: SoCal
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Posted: Sat May 28, 2016 8:52 pm Post subject: Re: Diagnosing dim headlights and dash lights |
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Thanks for the suggestions. Looks like I'll actually have to think for this one. I wonder if this might require a "can an average joe..." kind of thread _________________ 1971 Ghia coupe. Assume I know nothing and you'll be pretty darn close to the truth. |
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runamoc Samba Member
Joined: June 19, 2006 Posts: 5593 Location: 37.5N 77.1W
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Posted: Sun May 29, 2016 5:18 am Post subject: Re: Diagnosing dim headlights and dash lights |
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Quote: |
think for this one |
I did too. To test the individual headlight filaments at the bottom of the fuse panel would require the fuses for the headlights to be taken out. Otherwise, the power would 'back feed' thru the fuses to the other filament. But you can still test both sides with just putting that jumper on. Good luck. _________________ Daily driver: '69 Baja owned 44 yrs - Plan B: '81 Rabbit Diesel LS Deluxe - Plan C: '72 Ghia
Yard Art: 2 Sandrails
Outback: '69 Ghia - '68,'69,'70,'72 Beetle - '84 Scirocco, GTI - Pair of '02 Golfs-
VW Wiring = It's just wires |
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J1 Samba Member
Joined: February 10, 2014 Posts: 698 Location: SoCal
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Posted: Tue Nov 29, 2016 11:44 pm Post subject: Re: Diagnosing dim headlights and dash lights |
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runamoc wrote: |
Take a jumper cable, like the ones that have two 'alligator' clips. Look for the largest red wire on the fuse panel. That will be wire #30, always 'hot'. Put one end of the jumper cable on that and put the other end of the jumper cable on either the yellow or white headlight wires. You can hook to the individual yellow and white wires on the bottom of the fuses to check individual headlight filaments or to the top of the fuses where there is just one wire, yellow or white to check both low and high beams. If they are still dim, it's not the switch. Really, almost all cases you have described has been because of a bad ground. |
Thanks for this tip. Finally got around to trying this. Headlights brighten when connecting with alligator clips. What does that mean and what do I do next? _________________ 1971 Ghia coupe. Assume I know nothing and you'll be pretty darn close to the truth. |
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Mellow Yellow 74 Samba Member
Joined: October 14, 2014 Posts: 1615 Location: Sydney, Australia
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Posted: Wed Nov 30, 2016 4:04 am Post subject: Re: Diagnosing dim headlights and dash lights |
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runamoc wrote: |
Easy enough to troubleshoot without buying a lot of un-needed relays to find out that's not the 'cure' to the problem. |
It may not solve the problem but adding headlight relays will improve the headlights a lot anyway once you fix the problem and maybe they will fix the problem. Samba member Jay Brown does a good quality headlight relay kit for buses and Vanagons and there is no reason why you can't use on a KG. _________________ 1962 Karmann Ghia
1974 Deluxe Microbus
1985 Caravelle (Vanagon) |
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runamoc Samba Member
Joined: June 19, 2006 Posts: 5593 Location: 37.5N 77.1W
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Posted: Wed Nov 30, 2016 8:16 am Post subject: Re: Diagnosing dim headlights and dash lights |
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Quote: |
adding headlight relays will improve the headlights a lot |
Using larger gauge wire will improve the headlight voltage more than any relay could. When I rewire a VW I always run a 10 gauge wire from the battery to the headlight switch directly. The white and yellow wires after that are also 10 gauge. Good for over 400 watts. _________________ Daily driver: '69 Baja owned 44 yrs - Plan B: '81 Rabbit Diesel LS Deluxe - Plan C: '72 Ghia
Yard Art: 2 Sandrails
Outback: '69 Ghia - '68,'69,'70,'72 Beetle - '84 Scirocco, GTI - Pair of '02 Golfs-
VW Wiring = It's just wires |
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swavananda Samba Member
Joined: February 14, 2009 Posts: 889 Location: Can o' Scruz
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Posted: Wed Nov 30, 2016 10:03 am Post subject: Re: Diagnosing dim headlights and dash lights |
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runamoc wrote: |
Quote: |
adding headlight relays will improve the headlights a lot |
Using larger gauge wire will improve the headlight voltage more than any relay could. When I rewire a VW I always run a 10 gauge wire from the battery to the headlight switch directly. The white and yellow wires after that are also 10 gauge. Good for over 400 watts. |
The issue is the connection inside the switch. If you never have done it, put your volt meter on #56 at the switch or at the headlight plug and take the reading. Usually it drops 1 to 2 volts or worse, from the incoming line at #30. The relays bypass the weak link in the switch. Running larger wires will not gain that voltage back.
Last edited by swavananda on Wed Nov 30, 2016 10:08 am; edited 1 time in total |
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swavananda Samba Member
Joined: February 14, 2009 Posts: 889 Location: Can o' Scruz
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Posted: Wed Nov 30, 2016 10:06 am Post subject: Re: Diagnosing dim headlights and dash lights |
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J1 wrote: |
runamoc wrote: |
Take a jumper cable, like the ones that have two 'alligator' clips. Look for the largest red wire on the fuse panel. That will be wire #30, always 'hot'. Put one end of the jumper cable on that and put the other end of the jumper cable on either the yellow or white headlight wires. You can hook to the individual yellow and white wires on the bottom of the fuses to check individual headlight filaments or to the top of the fuses where there is just one wire, yellow or white to check both low and high beams. If they are still dim, it's not the switch. Really, almost all cases you have described has been because of a bad ground. |
Thanks for this tip. Finally got around to trying this. Headlights brighten when connecting with alligator clips. What does that mean and what do I do next? |
That means the switch is bad, By by-passing the switch with the jumper you proved that the rest of the circuit is fine . If you have a volt meter try the above mentioned test to read what your voltage output is after the switch. You can try and dissect the switch and clean up the contacts........ |
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Mellow Yellow 74 Samba Member
Joined: October 14, 2014 Posts: 1615 Location: Sydney, Australia
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Posted: Wed Nov 30, 2016 1:01 pm Post subject: Re: Diagnosing dim headlights and dash lights |
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runamoc wrote: |
Quote: |
adding headlight relays will improve the headlights a lot |
Using larger gauge wire will improve the headlight voltage more than any relay could. When I rewire a VW I always run a 10 gauge wire from the battery to the headlight switch directly. The white and yellow wires after that are also 10 gauge. Good for over 400 watts. |
Yeah, but adding relays improves them quickly and easily without the need to replace all the existing wires. _________________ 1962 Karmann Ghia
1974 Deluxe Microbus
1985 Caravelle (Vanagon) |
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J1 Samba Member
Joined: February 10, 2014 Posts: 698 Location: SoCal
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Posted: Wed Nov 30, 2016 11:38 pm Post subject: Re: Diagnosing dim headlights and dash lights |
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swavananda wrote: |
That means the switch is bad, By by-passing the switch with the jumper you proved that the rest of the circuit is fine . If you have a volt meter try the above mentioned test to read what your voltage output is after the switch. You can try and dissect the switch and clean up the contacts........ |
I removed my sealed headlight and measured 9 volts. Not sure if that's where I should be testing but at least it confirms a voltage drop and dim lights and that it's not just me going blind!
I also removed the headlight switch after wrestling with the rats nest of wires. Should my next step be to clean these contacts? And if that doesn't help is my next option to just buy a new switch? This is the original so I assume it's likely time to send it to switch heaven.
_________________ 1971 Ghia coupe. Assume I know nothing and you'll be pretty darn close to the truth. |
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swavananda Samba Member
Joined: February 14, 2009 Posts: 889 Location: Can o' Scruz
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Posted: Thu Dec 01, 2016 10:13 am Post subject: Re: Diagnosing dim headlights and dash lights |
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J1 wrote: |
Should my next step be to clean these contacts? And if that doesn't help is my next option to just buy a new switch? This is the original so I assume it's likely time to send it to switch heaven.
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It is a bit tricky to open the switch . There is a spring loaded BB that makes the contacts inside. Work in a open bare space so you can find the little pieces if/when they pop out on you. Clean up the contacts, If they are not to fried or corroded ........ Try..... and reassemble. |
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Chochobeef Samba Member
Joined: May 01, 2013 Posts: 811 Location: Ft. Worth, Texas
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Posted: Thu Dec 01, 2016 12:41 pm Post subject: Re: Diagnosing dim headlights and dash lights |
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Re-assembling is the hard part. Take it slow and don't be surprised if it doesn't work the first time or something pops out wrong. It will take patience. |
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J1 Samba Member
Joined: February 10, 2014 Posts: 698 Location: SoCal
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Posted: Thu Dec 01, 2016 2:34 pm Post subject: Re: Diagnosing dim headlights and dash lights |
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How much more life can I get out of this headlight switch by disassembling and cleaning?
It would certainly be preferred to keep the original but if I'm only slightly delaying the inevitable death of this switch I'd rather spend $25 on a new replacement and use my time fixing something else. _________________ 1971 Ghia coupe. Assume I know nothing and you'll be pretty darn close to the truth. |
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