Lights flicker and electrical system resets randomly

chrishall

Member
Joined
Sep 12, 2012
Location
Canada
TDI
2004 Jetta TDI
Hello all. This is my first post!

I have a 2004 Jetta TDI. 8 months ago it started showing signs of electrical problems, but not consistently. The dash lights and head lights will flicker while the car was at low RPM's. If I used the power windows during this condition, often the car would nearly stall. Adding any electrical load with Windows, power seats or A/C would cause the car to nearly stall. When I shut the car off during this condition, the dash goes blank, resets the trip KM's, resets the radio time, and the car makes a strange humming noise and sometimes the horn goes. I have to put the key back in and turn it off and on several times or add electrical load (like the brake lights) to make it stop. After it stops, the radio clock is 12:00 and the trip KM reads 0.0.

I took it to a dealership and they said some kind of relay had gone bad and they replaced it. The problem occured again a few days later. (but it was always intermittent)

I took the car back to the dealership and they said they found a problem with the generator. I agreed to have that replaced. I asked them why they thought the relay was the problem in the first place but they said the codes came up with a bad relay first, and then they tested the generator and it was not producing enough amps. (30 - 40)

The problem came back, but not for several weeks. This time they said the generator was bad (again) producing a few amps. They figured the replacement generator was bad so they replaced it again under warrantee. But they also said the generator was not charging the battery to spec because the battery could not take the charge. They also said the generator would not be covered for future problems if the battery was not replaced because the battery could be burning out the generator. I was planning to replace the battery anyway because it was over 6 years old and I live in a cold climate. So I had them replace the generator and battery at the same time.

The problem came back after 4 months. (which is now) I suspect when I take it back to the dealership they will have some new story to feed me. But the generator and battery are covered for replacement for 12 months, so I am hesitant to take it to another shop at this point because if the generator and/or battery are toast again, then I need the original shop to replace under warrantee.

Not sure what to do next. This car is otherwise amazing and has been for many years. So I am not in the mood to sell it. has anyone seen this before? Any ideas on what the problem might be or what I can test myself?

Thanks everyone.
Chris
 

BobnOH

not-a-mechanic
Joined
May 29, 2004
Location
central Ohio
TDI
New Beetle 2003 manual
sounds typical of a weak battery, but first check the terminals, big wire connections and grounds
 

Dodoma

Veteran Member
Joined
Mar 30, 2004
TDI
2002 Jetta White
The time is again to replace the battery and the generator or alternator, as long as it is done free.
 

Bkcorso

Veteran Member
Joined
Feb 28, 2006
Location
Phoenix, Arizona
TDI
2001 Golf
Using the power windows was almost causing it to stall ? Would the car start back up normally the next day ? Did you regularly have to get a jump start ?

If using the power windows was using all the available current so that even the computer couldn't keep the car running, You shouldn't have been able to start the engine.

I would certainly be cleaning ground connections.
 

chrishall

Member
Joined
Sep 12, 2012
Location
Canada
TDI
2004 Jetta TDI
Bkcorso: That's correct. When the lights are flickering (and that's not all the time) the use of anything with heavy load, like two windows at once, causes the car to nearly stall and resets the clock, the radio and the trip distance meter. But if the lights are not flickering (running normal I will call it) then this behaviour does not occur. By the way, the car always starts. Even right after these power problems exhibit themselves.

I will look at the grounding again. That is one thing I did earlier this year but did not appear to help.
 

chrishall

Member
Joined
Sep 12, 2012
Location
Canada
TDI
2004 Jetta TDI
One more thing I will clarify,

While the car is running and if the dash lights and headlights appear to be flickering, when I turn off the car the radio, clock and trip meter reset will always reset. (and sometimes the horm will sound)

While the car is running and the lights appear normal, when I turn off the car all systems remain normal as well. (clock, trip meter, radio, etc do not reset)
 

Bkcorso

Veteran Member
Joined
Feb 28, 2006
Location
Phoenix, Arizona
TDI
2001 Golf
It isn't fun, but removing and cleaning the major ground areas are a good idea. Not just "looking them over" If you aren't blowing any fuses, flickering is usually associated with ground issues. If your cluster is losing power I would find where that ground is and clean it. The resetting of the trip/clock/radio is an indication it has lost power.
 

krispy

Member
Joined
Mar 12, 2001
Location
Milford, CT, USA
TDI
Golf GLS, 2002, Indigo Blue
I had similar problems for months, and I finally fixed it. I had a rough idle, the engine would "pulse" and all the lights would flicker in time to it. The sunroof would not operate most times (but worked fine when the car was not running) and I would sometimes have the ABS/brake lights flash and get three beeps from the cluster. I cleaned all the grounds and sprayed them with electrical cleaner, and this made a slight improvement for a couple of days, but the problems came back just the same. It turns out, it was the Positive battery cables, and I cleaned them good from the alternator to the starter, and then the starter up to the battery, and all the wires in the terminal block on top of the battery. There was lots of green corrosion where everything hooked to the starter, and on a braided cable on the starter. Again, I cleaned everything good with a wire brush and contact cleaner, and now the car runs flawless. All the electrical items function normally,and no more flickering. I hope this helps others with this similar problem and who have cleaned all the grounds without fixing the problem.
 

chrishall

Member
Joined
Sep 12, 2012
Location
Canada
TDI
2004 Jetta TDI
Found time today to clean all connections (both positive and negative) from the battery. Neg to the bottom of the battery tray, and also connected across to the block. Pos on both cables as well. Also remove and cleaned all the positive cables in the positive cable tray terminal block. Used electrical cleaner and wire brush on all connections. Here's hoping the problem is gone. Will still take the car into the shop to check battery and alternator condition, as they are still covered for replacement if they are toast. Will update this thread with more info later.
 

RookTDI

New member
Joined
Aug 24, 2024
Location
Alberta
TDI
1.9l DOHC TDI
Did you figure out what the problem was exactly?
I have a Mark 1V 2005 jetta tdi that has all the exact same electrical problems yours had, windows almost stalling the car, the resets, everything. I didn't notice these problems happening until after I had swapped out my factory headlight bulbs for LED bulbs. Could that have been the cause?

Looking forward to hearing back
Thanks!
 

Alchemist

Veteran Member
Joined
Nov 3, 2007
Location
Lethbridge, Alberta
TDI
'04 ALH Golf
The OP hasn't been on since 2012, so don't expect a reply. As mentioned above, check all connections, both positive and negative, between battery, alternator, body and engine. It is probably a loose, corroded or burnt connection.
 

RookTDI

New member
Joined
Aug 24, 2024
Location
Alberta
TDI
1.9l DOHC TDI
Thanks for the reply!

Yea I'll have to check all of those, I'm going later to buy some resistors for my LED headlights I put in a while ago, none of these problems started happening till I made the swap, so hopefully that helps too!
 
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