Pulsing lights

mavapa

Veteran Member
Joined
Aug 29, 2000
Location
rome, ga
TDI
2001 golf
All of the lights on my '01 Golf pulse while the engine is running - headlights, dash lights, dome light if it's on, everything. It's a fairly high frequency, maybe a couple or so pulses per second. It is most noticeable at idle or at low speeds. They do not pulse with the engine off. Could this be the voltage regulator, or what?
 

puter

Top Post Dawg
Joined
Jun 19, 2007
Location
Tacoma, Washington
TDI
2002 Jetta GLS
I would suspect the battery.

The battery would be used to smooth out the current, if it can't maintain a very good charge then you would see pulses from the alternator.

I'm a CE person tho, not a mechanic, so it's just a guess.
 

gforce1108

Top Post Dawg
Joined
Aug 2, 2006
Location
Newburgh, NY
TDI
04 Jetta GLS BEW, 14 Audi A7 V6 TDI, 13 Porsche Cayenne V6 TDI
My buddy that rebuilds alternators says it's probably the voltage regulator. Not sure on these if it's internal to the alternator or inside the ECU (many new cars are now this way).
 

2004STARWARSTDI

Top Post Dawg
Joined
Oct 19, 2004
Location
LAKELAND, FL
TDI
2004 Platinum Gray GLS Jetta / 2006 Silver Jetta with DSG
pulsing lights

Take car to autozone or advanced auto parts. They will check charging system to include alternator, voltage regulator & battery for free. :cool: This will save you $$$ just replacing parts blindly.:D I once replace voltage regulator to find out the alternator was bad. Lost $$ on voltage regulator because they won't accept electrical items back!:mad:
 

VinW

Active member
Joined
Jan 1, 2003
Location
canada
I've got something similar but it only happens when the car is cold and the gears (auto tranny) switch. The interior/exterior lights all dim and return to normal all the same time as the gears switch?? As soon as the car is warmed up problem gone?? Anyone got some answers on this one? Is it the same thing just not as far gone?

...Thanks in Advance
 

cardinarky

Veteran Member
Joined
Oct 26, 2002
Location
arkansas
TDI
NB 99 White
VinW:

I have had the same problem on my 99 Beetle forever. It goes away as soon as the car gets up to running temperature. Car has 105K and has many electrical quirks.
 

mavapa

Veteran Member
Joined
Aug 29, 2000
Location
rome, ga
TDI
2001 golf
I had been leaning towards the voltage regulator. 2004SWTDI, I think your suggestion is a good idea.
 

mk3

Veteran Member
Joined
Sep 13, 2005
Location
Wisconsin, USA
TDI
03 Jetta GLS 5-speed
I wouldn't wait. You have a lot of expensive electronics in this vehicle that could be harmed by the rapid fluctuation of voltage and current. Could it be the clutch pulley on the alternator is slipping a little bit? I think the alternator should be thoroughly checked out.
 

kbrenny

Veteran Member
Joined
Jul 9, 2008
Location
Mora, MN
TDI
2002 Jetta wagon TDI
I looked into replacing the voltage regulator on mine when it started going south but it cost around $90 with a 90 day warranty and the entire alternator (rebuilt) with a lifetime warranty was $130. For the $40 difference I think I am just going to go ahead and do the entire alternator.
 

Gearhead51

Veteran Member
Joined
Jun 11, 2008
Location
Suwanee (Atlanta), GA
TDI
2000 Jetta
I just got my Jetta running. I have a similar issue. I would say that I get about 1.5 to 2 pulses a second. I've checked the voltages, and they fluctuate to 12.5 (off pulse) to 14.1 (on pulse). You can see the tach drop 100 RPM when the alternator loads, then it goes back up when the alt. unloads. I think I'm going to replace the voltage regulator and see what happens.

I know that you can replace the regulator without pulling the alt, but how on earth does the alt. come out? I got my car with a bad engine, and as I was doing the swap, I tried to pull the alt. in frame, and couldn't figure out how it comes out, so I left it in and swapped it on the stand before putting the new engine in.
 

VinW

Active member
Joined
Jan 1, 2003
Location
canada
VinW said:
I've got something similar but it only happens when the car is cold and the gears (auto tranny) switch. The interior/exterior lights all dim and return to normal all the same time as the gears switch?? As soon as the car is warmed up problem gone?? Anyone got some answers on this one? Is it the same thing just not as far gone?

...Thanks in Advance

I forgot to mention a "click" noise from what seems to be under the dash around my right knee at the same time that the light dims and the gears shift?
 

mattyc5094

Well-known member
Joined
Dec 14, 2005
Location
Patterson N.Y.
TDI
2006 jetta BRM,2000 Jetta ALH 2009 sportwagon tdi (totalled),1999.5golf tdi 1998 GOLF (4) RABBIT diesels, 81 Dasher diesel, 2005 DODGE CUMMINS
i get the same pulse with click on my 99 golf, thought it was auto trans but did a 5speed conversion and still does it when rpms drop down at shifts. this proves its not only on auto trans cars. definately a relay on the fuse block. could this be the glow plug relay giving glow plugs a little heat when rpms drop??? can someone help us out
 

puter

Top Post Dawg
Joined
Jun 19, 2007
Location
Tacoma, Washington
TDI
2002 Jetta GLS
do you have any engine codes, and if so do any of them read short to ground?

I have seen some of these symptoms when the ground under the battery is loose.
 

mattyc5094

Well-known member
Joined
Dec 14, 2005
Location
Patterson N.Y.
TDI
2006 jetta BRM,2000 Jetta ALH 2009 sportwagon tdi (totalled),1999.5golf tdi 1998 GOLF (4) RABBIT diesels, 81 Dasher diesel, 2005 DODGE CUMMINS
Thanks For How To Link, That Is Like My Bible, Great Links!. This Is Only A Cold Engine Temp Thing. Never Get It In Summer. Only Days Glow Plugs Kick In. Has Done This Since I Bought It Used 3 Yrs Ago. Would Like To See If It Is A Glow Plug Relay Under Dash. No Other Relay Is Set To Engine Temp Needs. I Do Not Have Engine Coolant Heater Because Car Was Auto From Factory.
 

Antsrcool

Vendor
Joined
Sep 18, 2007
Location
MA Springfield
TDI
2010 Cup Edition
that click is your glowplugs reamining on even after teh car is running for a few mins. when you rev past a certain rpm (cant remember whihc) you can hear teh GP relay kicking in and out......its all normal and your wasting money on a new ALT
 

PharoahTDI

Veteran Member
Joined
Apr 7, 2004
Location
Alliston, ON
TDI
None
I am just having a similar problem this morning. All the lights pulse on and off and get worse when I turn on my defroster. Also my scangauge shows the voltage going up to 15.2 volts. I know the battery is good and I have cleaned all grounds and contacts.
Could it be the alternator?
 

jasman19

Well-known member
Joined
May 11, 2007
Location
Vancouver, WA
TDI
2004 Golf
I'll toss my two cents in... I had a similar problem minus the voltage issue that you're describing with your scanner (multimeter?). My voltage off my alternator was 14.6 with a static voltage of 12.6 on my battery. I thought for sure it was ground issue, but I found out that the real issue was the 109 relay. I cleaned my grounds and I also ran a redundant ground under the battery box anyways. I though it was odd that the main ground cable stud is a inch from the headlight harness ground and the dash/ecu ground. I noticed a huge improvement in drivability, fuel mileage (so far it looks good), and performance. I mean, when I started it cold the thing was basically missing on a cylinder and the lights would go on and off in a very obvious fashion. Hope that helps, but I find it curious that you're voltage readings off your alternator are so high and low. The relay was $25 from the dealership and I know an alternator or a voltage regulator is more. I would take it to autozone like one of the other members suggested earlier and have the charging system checked out :D
 

jasman19

Well-known member
Joined
May 11, 2007
Location
Vancouver, WA
TDI
2004 Golf
I have an update on this issue that my help some of you other tdiers out there. After I replaced the 109 relay I noticed that the problem "got better" but what really caused the issue to "get better" was the outside temp warmed up for a couple days. After the temp dropped the problem came back and actually got worse. After troubleshooting my car for about an hour and not finding any issues I decided to check the fuel filter. When I drained it out a bunch of crap came out, so I decided to drain the filter down and reprime the system. This made all the difference in the world, and its even been down to near 20F and I've had no issues. I replaced the filter 20k ago, but the catch is that I'm running B20 so I suspect the B20 is freeing up some garbage that was in the fuel system from when the car ran diesel only. I have a new fuel filter on the way to replace this one, and I would advise anyone who is running biodiesel to change their filter atleast every 20k if not a bit sooner.
 

mk3

Veteran Member
Joined
Sep 13, 2005
Location
Wisconsin, USA
TDI
03 Jetta GLS 5-speed
Interesting. 20K happens to be the specified replacement interval for the fuel filter according to the manual. Drain at 10K and replace at 20K.
 

jasman19

Well-known member
Joined
May 11, 2007
Location
Vancouver, WA
TDI
2004 Golf
My manual says 30k for filter replacement, but I'm sticking with an earlier scheduled replacement. So far my car has been running strong since I swapped filters, and the temperature has dropped here recently.
 

TurbineTech

Veteran Member
Joined
Feb 22, 2003
Location
Burnaby, BC
TDI
2003 Jetta
Mine does the same thing. I just tonight took it back to the alternator shop that replaced it and he changed the regulator without removing the alternator and it helped a bit. It was going from 13.5-14 but was staying above 14 afterward with fluctuations in the decimal points. It is intermittant. I know I need to change my fuel filter and am going to do that next.
 

Po'man racing

Active member
Joined
Jul 8, 2009
Location
Middle Tennessee
TDI
2003 Jetta GLS Wagon 5spd
I'm having a similar issue with my interior lights with the car not running. When I open the door to get in the interior lights flicker and I can hear a relay under the steering wheel chattering in unison with the interior lights. The interior lights I'm describing are the map lights located in the sunroof switch housing and the lights above the rear door openings. My instrument lights don't have the same problem though, they burn nice and steady. Not trying to hijack the thread, just stumbled across this and it's similar to what I'm experiencing. When I get a chance I'm going to pull the panel under the steering wheel and try to see if I can feel which relay is chattering. I haven't had a chance to try and trace it to a specific relay in the wiring schematic yet.
 

Po'man racing

Active member
Joined
Jul 8, 2009
Location
Middle Tennessee
TDI
2003 Jetta GLS Wagon 5spd
This thread has been dead for a while but wanted to follow up on what fixed my pulsing interior lights. The problem progressed with the lights and I eventually lost function of my hatch release from the key fob and the button on the door. Found the clicking I heard under the dash to be the CCM under the dash. Bought a CCM from the dealer and it corrected the pulsing light condition I experienced.
 
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