VW Beetle Forum banner
1 - 7 of 7 Posts

·
Registered
Joined
·
44 Posts
Discussion Starter · #1 ·
Probably going to get flamed for the second picture but this is the third fuse box she's burned up in a year and a half. Went through everything today, cleaned all the grounds, ran a 4ga alternator wire parallel with the factory, added a block to negative battery terminal ground and for safety/testing a 110a circuit breaker. Also replaced the temp sensor as the temps were bouncing between 52 and 190. Temps stable now

Temp across all the connections is low but in retrospect I didn't hear the fans blowing hard when the A/C was on. Took it out for a test drive and it got sluggish and then the traction control and ABS light came on. Popped the hood and the circuit breaker was tripped. Reset the breaker and the fans kicked on high, ABS/TSC lights went out and engine power returned. So I'm pretty sure the fan(s) is what is killing the fuse box.

Came home and it tripped again, the drivers side fan was spinning slow and the passenger side fan was not spinning at all.

So do I replace both or start with the passenger side? Or is it the whole unit and if I can get one I'm in for a fun couple of days in the driveway?

Pics attached for humor and creative Dad testing.
Bottle Glass bottle Beer bottle Alcoholic beverage Mass production
Motor vehicle Automotive design Gas Auto part Automotive exterior
 

·
Registered
Joined
·
44 Posts
Discussion Starter · #2 ·
Quick update, for sure a bad fan switch. Jumped and fans came on. Replaced it and fans are cycling.

Pulled the circuit breaker out as I suspect the startup current of the fan was killing it and or as it was cheap Amazon it probably was tripping before 110. Temps across the new fuse box are 120-130F with everything on.
 

·
Registered
Joined
·
44 Posts
Discussion Starter · #3 · (Edited)
Resolved, bad fan switch, loose/corroded connections caused fuse box. Cleaned everything up an all is well.

For sure a strange situation. Guessing the battery got really low when she drove it home with the burnt fuse box and never got a good charge when I was testing it with the circuit breaker.

The car would lose power but no lights would come on, eventually I'd get a ABS and TCS light and by the time I got home it has a CEL. Pulled codes with OBDeleven and it was all low voltage related. Trans, O2 sensor, Airbag system all reporting low voltage.

Can't really explain why the fuse box burned up. Suspect that connection loosened up. I cleaned all the connections, ran an extra ground from the engine to the battery, put in a new fuse box and pulled that circuit breaker. Did a quick test drive and it started out running sluggish again but within a couple of blocks power restored. Drove it another 30 miles and it ran fine. Guessing the battery was really low, it did crank a little weak.

After that drive, I ran the car at idle for 30 min with everything on, lights, AC, heated seats, rear defroster, etc. and all is fine with the new box and wiring. Main lines got up to 160f but tend to hold around 150. It was 89 here today and I was working in the sun.

I did notice that the nuts on the new fuse box weren't really tight when I installed it. So I hit all of them before the first drive and then after the car cooled down, I was able to get about another 1/4 to 1/2 turn out of each and hit everything with terminal protectant spray. Going to put this on my weekly checklist.
 

·
Registered
Joined
·
2,550 Posts
Quick update, for sure a bad fan switch. Jumped and fans came on. Replaced it and fans are cycling.

Pulled the circuit breaker out as I suspect the startup current of the fan was killing it and or as it was cheap Amazon it probably was tripping before 110. Temps across the new fuse box are 120-130F with everything on.
what are you calling a bad fan switch? You mean the fan control module? i think that when the fans are bad they melt the green 30 amp fuse in the fuse box, third from L to R. Good to hear you got it cleared up.
 

·
Registered
Joined
·
44 Posts
Discussion Starter · #5 ·
what are you calling a bad fan switch? You mean the fan control module? i think that when the fans are bad they melt the green 30 amp fuse in the fuse box, third from L to R. Good to hear you got it cleared up.

There is two wire sensor/switch near the front of the motor, right side that I replaced after the 4 wire coolant temp sensor.
 

·
Registered
Joined
·
2,550 Posts
There is two wire sensor/switch near the front of the motor, right side that I replaced after the 4 wire coolant temp sensor.
You mean the A/C cut off switch mounted on a "Y" coolant hose ? one of it's hose goes to the electric pump one goes to the radiator and one goes to the flange on the motor. That switch puts both fans in high speed and cuts off the A/C. You're fans might still be pulling too much current when they go into fast speed mode.
 

·
Registered
Joined
·
44 Posts
Discussion Starter · #7 ·
Yep that's the one! They were not coming on at all, I jumpered it and ran the fans for 40 min in the driveway with the new box in. No issues. Replaced the switch and so far so good.

Wondering if the last fuse box loosened up a bit? With everything on today, I was pulling no more than 50 amps DC with my clamp meter. I torqued the heck out of this fuse box, found most of the connections on the fixed side were loose as well.
 
1 - 7 of 7 Posts
Top