Fuse 5 blown ('02 Jetta TDI)

In May'09, Fuse #5 blew (when starting car I assume or when I last turned it off). Today, while driving (at highway speed) the fuse blew again. Twice in 9 months is not normal...is it?

When the fuse blows, the cluster light for cruise does not work, and the parking brake light comes on solid and warning beeps for 5 minutes then stops (while driving). If you stop at a stop sign or whatever, the beeping will start back up again (for another 5 minutes).

So, this fuse controls heated seats, cruise control, and parking brake (sensor?)....

Does anyone know what else this fuse controls, or why/where it could be shorting out (or overloading).

I did not have cruise control on, nor were the heated seats on.

One other thing, both times the fuse blew, it was raining out (and windy)...

Fuse #5 controls the following: Comfort system, cruise control, Climatronic, A/C, heated seat control modules, day/night dimming mirror, control module and control unit for multi-function steering wheel. This is all I know referring to my Bentley manual.

ok, so I have basic heat and A/C, heated seats, and cruise control...
I don't have Climatronic, multifunction steering, day/night mirrir....

I wasn't using A/C, heated seats, or cruise...

So...where in the wiring would I be getting moisture/wet to short out...If not any ideas on how/why I am overloading that fuse?

HELP needed...

Well, I replaced the fuse (7.5A) and as soon as I started the car, it blew again....this time I smelled smoke. Turned off the car, and the fuse was blown.

So, was the burnt smell the fuse, or something inside the car, or something that got sucked in through the defroster....

Also, does anyone have any wiring diragrams or know anything about this circuit....

On a side note,
Why does the parking brake light on the cluster light up (red, at that)?
Isn't red supposed to be "don't drive, turn car off, ect"...???
Why is there an annoying warning beep?
Can I disable this warning beep?

I checked the WD's in my Bentley and it seems that this fuse 5 is wired to the cruise control switch(E45) and the cruise control push button switch(set) (E227). From there the wiring leads to the ECU. I don't see how any rain water could have penetrated these switches that are mounted to the steering column. My only guess is to do a sniff test in this area since you did detect a burning odor. If I come up with any worth while info I will let you know.

Much appreciated, I will start from there...
anybody else with ideas...

does this circuit include the seat heater elements, or just the heated seats controller?

ok, so I removed both heated seat switches and replaced FUSE# 5 and guess what....more issues of sorts....
the fuse did not blow so this is a good sign that one or both of the switches is bad (or there is a wire worn and shorted on the same circuit.)

BUT...when I turned the car on with fuse#5 installed again , my engine fans both came on permanently and at high speed. The thing is, my fans haven't worked for over two years. My AC hasn't worked either - I was thinking my fan controller(s) were bad or AC was low on pressure...

So what would cause my fans to run at full speed (my AC was off).

Is there anyone out there with a electrical diagram of the FUSE 5 circuit...

Just a guess. Possible that the fan circuit has shorted on the #5 circuit. You removed the excess load which was blowing the fuse when you removed the heated seats. They could run at full speed because they are shorted before hitting the rheostat that controls speed. Again, just a guess.

I've got a Bentley, pm me with a private email address and I'll scan that circuit page. Got to warn you though, it won't happen before Sunday, maybe later. I'm at work now, won't be home till late tonite, and I'll be wrenching on my own vehicle tommorrow.

cleaver said:

ok, so I removed both heated seat switches and replaced FUSE# 5 and guess what....more issues of sorts....
the fuse did not blow so this is a good sign that one or both of the switches is bad (or there is a wire worn and shorted on the same circuit.)

BUT...when I turned the car on with fuse#5 installed again , my engine fans both came on permanently and at high speed. The thing is, my fans haven't worked for over two years. My AC hasn't worked either - I was thinking my fan controller(s) were bad or AC was low on pressure...

So what would cause my fans to run at full speed (my AC was off).

Is there anyone out there with a electrical diagram of the FUSE 5 circuit...

Click to expand...

Just found one more issue.
When the car is running with the parking brake set, the daytime headlights are on...usually the lights are off until the parking brake is released....(without the headlights actually being turned on)

Here's some diagrams from the Bentley...

Mk4(2000) Wiring diagram: http://volkswagen.msk.ru/electro/wd_g4_00.pdf

2-Speed Fan Diagram: (May be Mk3...)
http://volkswagen.msk.ru/electro/g4/g4_wd12.pdf

Heated Seats: (Again, may be Mk3)
http://volkswagen.msk.ru/electro/g4/g4_wd19.pdf

Standard Equipment:
http://volkswagen.msk.ru/electro/g4/g4_wd29.pdf

Lots more are available but you have to read through a lot of russian to find the english links.

http://volkswagen.msk.ru

much appreciated, i will take a look at these tomorrow morning...

I guess I had better brush up on my russian

I have reviewed most of the diagrams but fuse 5 circuit goes everywhere it seems...I think I need some advice from an electical guru...................

I plugged my multimeter in to test the current on Fuse#5 (no heated seat switches installed); this is what I observed:

Current Draw: 0.5Amp
- both cooling fans on high speed
all other "systems" working fine
- recirc servo-motor works again (and recirc light beside A/C light)
- daytime headlights work as they should
- parking brake light off (no beeping)
- cruise control active again
- comfort system module working again

So the only items that have issue are the heated seats switches installed and both cooling fans are on. There has to be a short between the cooling fan LOGIC and the heated seats (since only 0.5A being drawn)...

Questions:
1. Does the heated seats switches draw a lot of current when they are both set to "zero" off?
2. Does anyone know where the cooling fan logic could cross this fuse 5 circuit?

Try unplugging your Air conditioning pressure sensor. I think it is mounted just in front of the firewall passenger side.

Then replace fuse 5 and see what happens.

I will work on other possibilites.

Fuse 5 also supplies your fresh air door flap motor.

I pulled connector off of A/C pressure switch, I think. It is located behind to left of anti-shudder valve, yes? (pretty much under in-cabin filter area.)
Once I re-placed fuse #5, and started car, both fans did not turn on this time. Engine temp was about 8*C (inside my warehouse).
So, I replaced both heated seat switches and fuse #5 and all is good with the AC pressure switch disconnected.

The only concern I have is that the AC pressure is good, and I have a short somewhere along the circuit....

Cleaver,
I think that your AC pressure sensor has failed, is loading down the circuit, and is sending a signal to your AC system that you have very high pressure in the system, which causes the fans to run.

Since high pressure is impossible in the AC system this time of year (pressure follows temperature), you know the sensor is bad.

Just leave it unplugged, put everything else back in service, and see if you never have any other issues.

To replace the sensor, you just unscrew it from its base. Think of it being screwed into a valve stem. It might leak a very little bit as you unscrew it while in an intermittent position, but once it is completely unscrewed from the schrader valve it should be leak tight.

Dan

very much appreciated, I will leave it unplugged as soon as I can get the connection covered up. (we have too much salt and crap on the roads right now - I actually have junks of powered salt on my car body that I can "scoop" off). I guess I need a car wash .

I will plug the heated seat switches back in and see if I blow the fuse again (with the high pressure switch unplugged).

I noticed that the both cooling fans alternately spin high for 3-4 seconds, then spin low speed for 3-4 seconds (rather than spinning at high all the time as I posted earlier).

You think this is still a bad AC Pressure sensor?

I will be installing the heated seat switches tonight/tomorrow so I will let you know if the fuse blows again....

Mike

Cleaver,
Are you saying that the fans are still cycling as you describe? Or that they WERE cycling as you describe until you unplugged the pressure sensor?

That unit is often called the high pressure sensor or the high pressure switch. but it is not a switch after about May of 99, it is a sensor.

And a bad sensor could cause either continuos high speed fan operation, or high then low (I have actually seen that before), or no fan operation. Theoretically it could cause continous low speed operation, too, but I have not seen or heard of that.

Good luck.

The fans were high, low, high, before i unplugged the sensor. I will take your best judgement and accept that the sensor is bad....I took a quick look at the wiring and haven't found any shorts along the way (worn wires, ect...)

I will pick up a sensor at some point, not really worried until spring/summer hits.

Very much appreciated Dan and all others that have provided input...

I would like to give an update on this 6 month old thread but there is really nothing to give (except some confidence).

I am confident that the sensor is bad, I didn't have time (lazy) this summer to replace the sensor so I don't know for sure. After blowing 3-4 fuses (#5) I haven't had any problems with this circuit since unplugging the sensor.

I will give an update next summer (LOL) when I get around to finally fixing it.

Sorry for the crappy update, but thats all I got....

I am having the same issues as you were with number 5 blowing... Have you had anymore issues since unplugging the A/C sensor?

no, no issues since. I did buy a new sensor and plugged it back in and the fuse hasn't blown since.

Hi, fuse 5 keeps blowing as soon as i put on heated mirrors, and hand brake light stays on until i put a new fuse but turn off heated mirrors. when fuse is blown, the air recirculate switch also trighers the handbrake light. where do i start looking?? thanks

Sounds like a short in the heated mirror wiring: I don't believe that bad mirror elements can do this, but it might be something to remember to check anyway (if nothing else is found). Check the wiring in the flex boot in your driver's side door. If that's not it then you're likely going to have to keep looking around.

Has there been any work/activity in either of the front doors?

Haha thanks but figured out the problem this morning. when i changed my heater core i had pinched pin 1 of the CCM under the steering column which was direct short to ground!!