Fuse #4 Blow every time the ignition is turned on!

Like the title mentions........I've been fighting this issue all winter (at least 5 months). I've done tons of searching on the net and forums for answers but to no avail.

Fuse # 4 blows as soon as the ignition is turned on ........this means no heated seats, no backup light, ESP light on the dash stays on and the ESP button does not work and from what I've read, possibly no A/C but can't check that now since it's cold outside.

What I have done so far, I cleaned the grounds located on the drivers side under and in front of the battery tray. I also opened up the big harness in front of the engine to see if there was any frayed wire but not this time.

I've read a thread where they mentioned a short coming from the heated windshield nozzle and a severed wire where the hood hinge is.

So, I looked into it and guess what I was convinced I found the problem.

I cleaned up the whole area without connecting back the wires together but making sure they were not touching nothing. Meaning, no more short and the fuse should no longer blow right?.......wrong, put a new fuse in and as soon as I turned the ignition .....the fuse blew.

Checked the bulbs for the backups but everything looks fine.

I order a short find but not convinced that is going to help so I depending on the gurus on this forum.

I've also inspected under the seat but nothing out of the ordinary, I'm planning to remove them this weekend to have a closer look for a possible short.

I've came across plenty of threads with this exact problem but they all die off without a solution or problem found. Almost everyone of those threads are cliff hangers.

I would really appreciate everyones input, especially the one that had the same issue.

Thanks to all in advance.

Get an multi meter and isolate and check separate circuits/items for resistance/continuity. Most meters have a setting where the will emit a sound if there is no resistance i.e. A short.

The wires on the reverse light switch harness are prone to wear. Mine were broken right where the harness plugs into the switch by the shift tower basically underneath the battery box.

First try to find a circuit breaker to put in place of the fuse. Next, unplug all of the components on that circuit and see if blows the fuse. If it doesn't, start plugging things in until it blows.

If it still blows with everything unplugged, well, you have a bunch of wiring to open up. Dig into those threads you mentioned and check everything that is suggested, no matter how crazy it may seem. While looking, be sure to keep your eyes open for wires in unusual spots, or maybe black areas that shouldn't be black or shiny areas that shouldn't be shiny. These are some signs that things are rubbing when they shouldn't be.

Thx Dieselmonkey02 for the quick reply very much appreciated.

Concerning the reverse light switch harness under the battery tray, I had all that out last week to clean the 3 grounds that were underneath. Needless to say they were fairly clean but I took them apart and cleaned them anyhow.

I also ordered a Bentley Manual for my car hoping that will help me figure things out but I'm not going to hold my breath on that one. It should be arriving in a couple of weeks.

It will probably come in more handy when doing mechanical repairs, my "forte" is not electricity.

As for a multi meter it would probably be a good time to replace my old one but if you would be nice enough to give me a crash course how to attack the problem with a multi meter .......I will be all ears.

Whitedog:

Don"t have a circuit breaker but after wasting a bunch of 5 amp fuses I found a thread where he made one with a car light bulb. When I plugged the bulb to fuse#4 the bulb stays on. The theory would be once the short is found and fixed the bulb should go off.

I attacked the problem in this manner last week with the bulb and checked the grounds under the battery tray and the backup light on the trunk lid. I was hoping the light bulb would of went off while wiggling the wires. That didn't happen.

I will most probably taking all your advise and applying it this weekend but the only thing is that they are announcing -33C that is -27F. Even in a garage it still is pretty cold. My luck, a cold front which is pretty rare during this time of year.

Could you direct me a little more concerning where I can find that harness. Did a little searching......correct me if I'm wrong plz, If I follow the reverse switch on the transmission it should bring me to the famous harness plug.... right.

Once again, thx for the input.

Get yourself wiring diagrams and see what is on that circuit and go from there. The light bulb trick should work nicely to allow you to isolate the short.

Its possible that a control module is shorted internally and causing the short but you won't know this until you start methodically troubleshooting. Going around and randomly doing things is a poor way to troubleshoot and can end up setting you up for a wild goose chase.

Just unplug your seat heater for example and check across the pins hot wire to its negative wire or a ground. It should have some resistance (not sure of any spec), if it has zero ohms it's probably shorted. Or unplug every thing on that circuit and plug in one thing at a time until the fuse pops , the part that blows the fuse would be the culprit.
It seems to be something on that circuit that is always on or has power at all times that the key is on is the problem. Or a broken power wire somewhere.

A vag com scan may tell you what is not working too.

I used an old sealed beam headlamp bulb to find shorts. Work great, and I used to get plenty of them that had one good filament left. It'll be nice and bright with a dead short, but will dim if you find the culprit while wiggling wires around, and no need to constantly be resetting it like a circuit breaker.

Thx once again guys for all the responses.......

I made a few phone calls and I just might have some willing to scan the car with a Vag com.

I'll try to get out there later this evening.

I guess the next best thing to try unplugging everything on the circuit.

I understand unplugging the heated seats, high pressure switch for the AC, heated nozzle, rear brake lights but is there a connection somewhere for the "ESP"?

Any other input is very welcomed ...... willing to try anything at this point.

If you get everything except the ESP unplugged and it does/doesn't blow it, it takes that out of the equation.

I'm laughing my head off and feeling stupid at the same time ...... oh boy, I don't know why I didn't figure that one on my own.....
Sorry buddy ....
I'm still laughing

To save you on the fuses and help locate the short, I recommend a tool similar to S&G Tool Aid 25100 Short Tester (around $30.00) . I had one that was similar from the Snap Off truck when I use to wrench at the dealer. The key benefit is that it would act as a circuit breaker and reset, so you dont burn thru a bunch of fuses. The hand held gauge picked up electrical field where the short was in the harness. As others have mentioned, the more you can isolate the circuits, the easier it will be to pinpoint.

I had a fair amount of success with the tool (still have it). If for only the automatic circuit breaker. The gauge worked on several of the shorts I encountered. Back in the day, electrical shorts didnt pay cr*p on warranty book rate, you got a flat 50 time units to diagnose and the time for what ever the part was that you needed to replace, if applicable. (On the other hand, insurance & customer pay electrical was gravy work ) In SoCal, I use to get at least 1 or 2 a week that would require a harness repair due to a radio theft. Fond memories ;-)

kbaisley,

Thanks a lot for the amazing information, wish you would of sent it a week earlier. I ordered a short finder (the electronic thing that beeps in order to find your short.).

If that doesn't find it, I'll consider looking into the tool you mentioned.

Now for all you people out there........

Yes, I did order a Bentley manual but have to recieved it yet, I can never understand why the shipping is so long between US and Canada.

I got my codes read but the fellow said its best he clears all of them and then re-reads them in a week because he thought there was a lot of old codes that were not vleared.

I also found a fellow in my area that was selling a Vag com, I should be a proud ower of a Vag com soon...

Nevertheless, I was planning to act the issue today since I had the time. So, I started planning out where I should start.

As I was looking into disconnecting the heated seats first........I searched the net for some instructions that just put more questions and doubts in my head.

I have no problems removing my seats which I figure is probably not necessary. Where the problem lies is.......which one of the connectors is for the heated seat????

Some posts say that if I disconnect the airbag and then connect the battery (which I need to do to see if the short is still there after I disconnect the heated seats.) it can cause the airbags to go off.

Now, what I was thinking ......if I can just disconnect the heat seat without unpluging the airbag I should not have anything to worry about.

My questions are ..........

1 - Can anyone tell me which connector is for the heated seat????

2 - Is there any danger disconnecting all the connectors under the seat and then connecting the battery to see if my fuse still shorts???

Just for additional information.....the only thing that is electric (besides the heat) is the back rest and nothing on the passenger seat. But they both have 3 connectors on each side.

Thanks again for the help!!!!!

UPDATE:

Not sure if GOOD or BAD.

While waiting for a response from the ubove post, I decided to go fidel around the car with my new Instrument (Short finder...Beeping one).

I started first with the 12v bulb plugged into fuse 4 and wiggled wires from the heated seat connectors, engine bay, trunk and under the dash. The light bulb stayed on the whole time and did not even flicker. I even disconnected the A/C high pressure switch hoping that the bulb would go off and I would have found the problen immediately but no....Light stayed on.

I then disconnected the battery and and connected the beeping transmitter onto fuse #4 and started exploring the wire harness, heated seat connectors etc.

I did not discover anything special, so I decided to wrap everything up and wait to see what responses I got on the forum and attack the issue intelligently.

As I put everything together, I dropped the 12v bulb and the glass bulb broke ....making a hole the size of a pencil eraser. the filaments were intact so I wondered if the buld would light up anyways.

So I plugged up the bulb and turned on the igniton.......low and behold the bulb lit up for only a few seconds and then smoked.

So, I decided to put in a new fuse in #4............I turned on the ignition and it didn't pop......I almost fainted (Not). I started the engine and no more "ASR" light on the dash, heated seat are working and so are the back up lights........dont know if A/C is working....its still too cold out.

I know that the problem is not resolved the right way and I'm convinced that the fuse will blow again but I will keep you all posted. I just hope it doesn't happen while driving to Florida this summer because my wife will loose it on me.

Till Later

Thanks a million

I didn't even think to ask if it was the right amperage fuse. K.I.S.S- keep it simple stupid.
Who knows, the electronic stuff on these cars sometimes has a mind of its own.

Believe me it was the right amperage fuse ....i went through enough of them .......lol
Problem has not come back yet. Im convinced the I must of moved something and now its not grounding itself causing the fuse not to blow.......to be followed.

Tech tip to pass along

IMO, VW seems to be the most unreliable when it comes to fuse diagrams.
I don't recall even a label inside the fuse cover of the driver side dash fuse box.
Lord knows the Jetta's owners manual wasn't that accurate with its fuse diagrams.
I have found it a good practice to open up the various fuse,relay box covers and take good close up pictures. I did this on my cars when they were new, so the photos would be accurate.
Take photos when the car is running good without any troubles.
This way you have an accurate picture of what fuse goes where.
You know which fuse positions should be vacant or have a fuse installed, you know what color fuse goes in each position and therefore it's amp rating.
It's easy to pull out a fuse and put it back in the incorrect position.

Thanks edge130,

Not a bad idea, Ill make sure to do that......it wont hurt for sure.

Just wondering if you had found the problem and this was another dead end thread that you had complained about in your very own post? Or did you never find the issue?

You couldn't make this up !

EZTiger 12 - Thank you for what looks on the surface anyway like a ridiculous addition to the post. How could that have fixed the issue, it makes no sense !
Well, I shared your frustration attempting to fix this issue on my wifes car and in desperation tried your fix - I'm mad right ?
I took a blown fuse and soldered two wires to the pins (after exposing them) and then to a 12v brake light bulb that was lying around. I didn't go as far as breaking the glass, I didn't need to.
I plugged it onto #4 fuse holder and the bulb illuminated, then it dimmed, then it got bright again and dimmed once more. This went on for 30 seconds or so until the bulb went out and stayed that way.
That fixed the issue, I put in a fresh fuse and its worked to this day ! (months ago). I don't do forums, I guess you would call me a lurker but I had to join (I will revert to lurking following this post) and pass this on, just because its total madness but it did work !.
I hope this helps someone in the future because the fault was causing significant hair loss..

It might have been the G65 High pressure AC switch. I had exactly the same issue (and I suspect that you have actually read my posting when you have mentioned in your initial posting that you have read about it somewhere on this forum). I tend to believe that something was casing a short in the G65 sensor switch and the short was somehow eliminated when you have removed and re-installed it.