Identify this Dash Relay / melted wire

[floodwood]

I went to turn on the van this morning and it wouldnt start / weak start. As I went to check to see if I had killed the battery by checking the headlight switch, white smoke started emitting from the dash behind the fuse box!

I quickly shut off the van, removed the keys, and thankfully a fire extinguisher was not needed. However, one brown ground wire was totally melted. Tracing the issue back, it appears that a heavy red wire leading to what I believe is a 50 amp fuse overheated, melting and breaking the brown wire in the process. Thankfully the damage was limited, and i removed the little metal strip thing that I think is a fuse

I have a few clarifying questions for the samba to diagnose and repair this issue.

1. What is this relay? 251-919-505 // 12V // 70A
I suspect that it is an AC relay, but in my tintop this relay was located in the back in the D pillar and it was not present in this area.
This thread seems to imply its part of the Rad / AC system, but again this was not present on my AC tintop.
https://www.thesamba.com/vw/forum/viewtopic.php?p=7089318

2. Is the little shitty metal strip inbetween the posts a fuse?

2a. Where can a new one be purchased?

3. Will replacing said fuse resolve this problem?

4. Clearly the post where the red wire comes in overheated, melting a ground wire for another circuit that happened to be touching it - see blue circle in picture 3. Where does this red wire go and what could be causing the overheating?

5. Is the car safe to start and drive since this fuse has been removed, thus breaking the circuit? As for the melted brown wire, this should be a simple fix to recrimp and reground that circuit to the ground tree.


My working theory is that this 50 amp fuse wore out and had high resistance, thus overheating and melting the brown wire that was touching it, thus causing the smoking / fire situation. However, I am perplexed how this happened within 2 seconds of trying to start the car.

[crazyvwvanman]

From what I see the brown wire rubbed against the screw head of the direct battery feed thick red wire until it shorted to the screw head.
Then battery current flowed from the red wire's screw head into the smaller brown to the ground tree and melted the smaller brown.

The thick red wire only feeds the radiator fan high speed relay through the 50 amp strip fuse.
No current flows through that red wire unless the rad fan is running in fan jet mode.
So no reason for the red to get hot if fan not running in high speed.

Mark

[Silverghost500]

I believe that is the relay for the radiator fan. The brown wires are ground wires that are going to that round, multi connector screwed into the bodywork.

I wouldn't recommend driving it just yet. Still need some troubleshooting. Might look at the wires going to the radiator fan, the resistor behind the left headlight, and inspect more of the wiring there under the dash where the wires fried.
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[ALIKA T3]

Like said, this is the 50 amp fuse for the high speed fan relay.

From the look of it, somebody worked in there and did a shit job. The left wire should be pointing down or running horizontal as to not stress it.
Also that burnt mark is from another wire that arc'd on the screw, prolly a ground wire....
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[floodwood]

I bought a 50 amp MIDI fuse to replace the old one as suggested in other threads.

This relay is clearly for the radiator fan as mentioned. However, I am still not clear if this is an A/C related relay, or if it’s required for regular functioning of the radiator.

[crazyvwvanman]

It is the high speed fan relay.
Needed whether you use A/C or not.
Shown in the A/C wiring diagrams though it acts independently of the A/C.

Mark

[floodwood]

As an update to this post, I was able to repair the melted ground wire and put in a brand new 50 amp MIDI fuse.

Testing voltage on both lugs showed that these are always powered.

After starting up the van and running & driving it for about 20 min, there were no repeat issues. Additionally, an IR gun showed both lugs at 73 degrees / ambient temperature both before and after the test drive / radiator cycle. I also ran the AC for a few seconds and the lugs did not heat up at that time either.

It would seem that I am out of the woods and have fixed the problem, but wanted to see if there is anything else worth checking before embarking on a 500 mile trip this weekend.

[ALIKA T3]

[GreggK]

[quote="floodwood"]I bought a 50 amp MIDI fuse to replace the old one as suggested in other threads.

Could you show the fuse you used to replace with? Thanks.
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[floodwood]

https://www.amazon.com/50A-Midi-Fuses-Automotive-A...d_source=1

[GreggK]

Thanks for the pic. Same thing I saw but wanted to confirm. Glad you got it sorted. Take care.
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[floodwood]

Pleased to share that after my repair last week, I was able to successfully head 500 miles upstate for a soggy weekend of bushwacking and swimming with the dog and friends.

Thank you all for the wealth of knowledge here. This thread can be marked as "SOLVED" for anyone that has a similar future issue

[dobryan]

Good job. And thanks for the report back.
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