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Discussion Starter · #1 ·
I have a 2002 Jetta TDI Manuel. New to me from brother.

While there are some issues I can deal with ....soft touch turned to goo, etc there is one thing I am worried about.

He said the lights(all electrics) will go out intermittently. Head lights, turn signals, radio, interior lights. He says the car runs fine while the electronics are out(except no headlights). Usually only happens for a few seconds but occasionally will last minutes. Longest it has happened is 10 minutes and the lights all come back on by themselves.


Any Ideas on what could cause this and what needs to be done for fixing? He is a outboard mechanic and has kept the car up great, but he doesnt like to mess with wiring/electrics. I'm sure he has checked the basics. Any ideas?
 

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Discussion Starter · #2 ·
Any Ideas?

I've seen the low vs high beam discussions, the interior lights go off, and the lights won't turn off threads. But I didn't find one on all lights going off intermittently. I have to pick this up and drive it 1700 miles in Dec.

thanks
 

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Likely corrosion or a bad connection I would think. I would inspect all of the wires around the battery and the headlights. Make sure they look serviceable, the connections are tight and corrosion free, and lastly that any grounds are tight and properly grounded.

9 times out of 10, electrical problems are due to bad grounds. The other "1" something is broke.
 

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Likely corrosion or a bad connection I would think. I would inspect all of the wires around the battery and the headlights. Make sure they look serviceable, the connections are tight and corrosion free, and lastly that any grounds are tight and properly grounded.

9 times out of 10, electrical problems are due to bad grounds. The other "1" something is broke.
This and check all your fuses for corrosion and bad contacts.... I just had one of the fuses were loose and a lightly corroded , when I Hit a bump the dash light went off, abs light lite, think the head light also went off.... one of the fuse in on top of the battery was corroded and the contact was loose..... fixed, no issue since. Talk about optimum location to place a fuse box with all the acid fumes.....
 

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Discussion Starter · #6 ·
Thanks for all the info, Now I have a few good places to start looking. I wanted to make sure the headlights failing mixed with all other electrics going out didn't point at something specific. Appreciated.
 

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Discussion Starter · #7 ·
I drove the car 1100 miles yesterday. Quite the stressful ride but all went as well as I could hope.

After about 200 miles the battery light(red) started coming on and off seemingly randomly. It would disappear for an hour then come back and blink(not rhythmically) and would even stay on solid for a few minutes, then I wouldn't see it for an hour. Turning on accessories(radio, wipers, etc) would sometimes trigger the battery light, sometimes not.

I noticed the headlights and the interior lights constantly flickering, switching between normal and dim in 1 second intervals.

Toward the end of the ride(17 hours) the interior lights would fade away then come back, the gauges would lose power when this happened, and the fuel gauge didn't work for a while(showed empty), then started working again.

So now my list of possible culprits is

ground under the battery

cable from battery to alternator

battery and battery connections

regulator in alternator

pulley/pulley clutch/belt on alternator

Ignition switch.



Not to familiar with how to check all these, but I will do some research on each one.

Also someone I work with and who is a mechanic mentioned it could be the computer, but everything seems to be fine except for the light show. ~50mpg at 70-75 mph.

Drove it to work today, same light show, but ran fine. Hoping to get some time this week to start on it.

Anyone have any other ideas with craziness I mentioned.
 

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.............
So now my list of possible culprits is

ground under the battery

cable from battery to alternator

battery and battery connections

regulator in alternator

pulley/pulley clutch/belt on alternator

Ignition switch.


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Check the fuses on top of your battery.... for corrosion or loose contacts... VW MkIV notorious problem area., some one decided that battery fumes won't corrode contacts and the best cut cost placement for a fuse box is right on top of the battery...... Check for the wiring for any gray or greenish tarnish oxidation.... check contact for burn marks indication of wiring / contact corrosion. You can search what each of those fuse does....

Probably not the alternator / ignition switch.... otherwise your car would shut down or have other issues. such as a dead battery or car won't start.... battery is there as a buffer for the electrical demands and start up.....

Could be a bad connection any where, but the best place to start is right at that fuse box.
 

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Check the fuses on top of your battery.... for corrosion or loose contacts... VW MkIV notorious problem area., some one decided that battery fumes won't corrode contacts and the best cut cost placement for a fuse box is right on top of the battery...... Check for the wiring for any gray or greenish tarnish oxidation.... check contact for burn marks indication of wiring / contact corrosion. You can search what each of those fuse does....

Probably not the alternator / ignition switch.... otherwise your car would shut down or have other issues. such as a dead battery or car won't start.... battery is there as a buffer for the electrical demands and start up.....

Could be a bad connection any where, but the best place to start is right at that fuse box.
this. also, I have seen the main positive cable INTO the battery top fuse box short internally. you can replace that for $30.
 

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Discussion Starter · #10 ·
Great info, thx. I checked the voltages before leaving for work this morning. 12.4 off, 14.3-14.4 when running. So Fuses, grounds. cables, will be my focus this weekend. A brief look at the fuses on top of the battery looked good, they had some VERY faint white/gray corrosion on them, very slight, looks like a couple of dried water stains. I will clean those off, but they look good.

Also My brother put in a new (non VW) radiohead and said he has had trouble reading the computer with it plugged in, Radio needs to be unplugged to read the computer. So I am trying to get him to dig up the stock radio so I can switch it back.
 

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Great info, thx. I checked the voltages before leaving for work this morning. 12.4 off, 14.3-14.4 when running. So Fuses, grounds. cables, will be my focus this weekend. A brief look at the fuses on top of the battery looked good, they had some VERY faint white/gray corrosion on them, very slight, looks like a couple of dried water stains. I will clean those off, but they look good.

Also My brother put in a new (non VW) radiohead and said he has had trouble reading the computer with it plugged in, Radio needs to be unplugged to read the computer. So I am trying to get him to dig up the stock radio so I can switch it back.
K line issues definitely
 

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Discussion Starter · #12 · (Edited)
Can you elaborate. Going to start researching K-line right now. What is it? Can it cause the light show on my dash as well as causing the computer to be unreadable?

EDIT: reading the Rosstech info on K-Line right now. Yet another reason to slap my knucklehead brother.
 

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Can you elaborate. Going to start researching K-line right now. What is it? Can it cause the light show on my dash as well as causing the computer to be unreadable?

EDIT: reading the Rosstech info on K-Line right now. Yet another reason to slap my knucklehead brother.
If you have the older VW that is non-canbus units, Leave the K-line un-hook, just tape it off, cut it but don't ground it. If you have the Can_bus units , you'll needed an adapter otherwise dealing with constant resets, not sure if that would cause your headlight or dash to dim but definitely would cause your ECU issues. Ran fine for me 10+ years that way.
 

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Discussion Starter · #14 ·
Is there a thread on that procedure? I don't have much experience. Sounds like I need to cut a wire and tie it up. Where is this cut made. On the new radio side or cut a wire coming out of the cars harness? Car should be non canbus(2002 tdi jetta).
 

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I had this exact same issue recently..I tested the battery and alternator and they were fine. I checked all fuses..i checked top of battery and i checked under the battery and checked all major grounds and redid some...Nothing permanently fixed the issue. I knew it had to be a ground so i used a diy on here to run a hyper grounds from one fender to throttle body to coil to central point to transmission then to battery then to opposite fender and fixed all the issues 100%.
 

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Is there a thread on that procedure? I don't have much experience. Sounds like I need to cut a wire and tie it up. Where is this cut made. On the new radio side or cut a wire coming out of the cars harness? Car should be non canbus(2002 tdi jetta).
at the top of the form page is the FAQ/DIY thread, in there is a link and info regarding the K Line :thumbup:

edit - for the lazy : http://www.ross-tech.com/vag-com/aftermarket-radio.html
 

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Discussion Starter · #19 ·
Thanks to all for all the help. I've never messed with wiring before. This all a little over my head. I am gonna read everything again. See if I can figure out where to cut the K-Line and check all the grounds.
 

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Discussion Starter · #20 ·
Had very little time this weekend to do anything but clean the battery terminals.

I 'm having a hard time finding the ground points in the TDI, although to be honest I looked at it for a few minutes max.

The engine light is a sensor that needs to be fixed(I was told), but I can't read the computer until I take out(or unplug) the new fangled radio.

here is a quick video of what happenes. Once tgis week it went a whole commute without a battery light or dash light failure, but usually it does this every 15 minutes....

[video]http://vidmg.photobucket.com/albums/v74/mjayn/20151216_163303_zpstr0wpy8x.mp4[/video]

Engine doesn't die and headlights and radio seem to always stay on, so thats good, but its still driving me crazy.
 
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