Always check the fuse...

[budgetzagato]

Spent part of today fixing a lot of dead electrical accessories in my Scorpion. Turned loose the fuse panel and other things to figure out the source of the problem. Turned out to be a bad fuse B.

Fuse B does way too much, heater fan, brake lights, turn signals, tachometer, to name a few. The fuse that was bad was a cheap 8A fuse with a plastic core. All the rest are ceramic.

It looked fine but it wasn't making contact. The plastic melted at the ends allowing a loose fit and loss of contact.

No more plastic fuses for me!

 

[Rupunzell]

Poor connection = higher contact resistance which results in significant heating of that connection and loss in power to the fused system.

This is why all connections must be clean and solid. Poor connections are not only a cause significant damage, they can cause a fire....

Those EU open fuses were ceramic for a good reason, they have better mechanical stability with time and temperature. If the plastic body fuses get hot and begins to soften, the mechanical contact force will lower causing a poor connection and higher contact resistance, then lots of heat. This is positive feed back in self destructive direction.. Eventually, the connection is lost or cooked or even flame on..


Bernice

Spent part of today fixing a lot of dead electrical accessories in my Scorpion. Turned loose the fuse panel and other things to figure out the source of the problem. Turned out to be a bad fuse B.

Fuse B does way too much, heater fan, brake lights, turn signals, tachometer, to name a few. The fuse that was bad was a cheap 8A fuse with a plastic core. All the rest are ceramic.

It looked fine but it wasn't making contact. The plastic melted at the ends allowing a loose fit and loss of contact.

No more plastic fuses for me!

 

[budgetzagato]

Yep!

Don't I know it.

At least this was an easy fix. My Vanagon has an intermittent ignition issue that's giving me grey hair.

 

[kmead]

Ignition issue or is it the fuel pump relay? My old Golf had an intermittent fuel pump relay problem where there was a failed solder connection inside the relay. It drove me nuts as it would run perfectly fine all the time and then wouldn't start at the most inopportune times.

What a pain. Replaced the relay and never a problem again.

 

[budgetzagato]

Ignition...

Specifically the hall effect sensor in the distributor, or the wiring. It developed gradually, started as tach dropping out, then developed into stalling. First tried tune up and new ign. switch. Swapped in a used sensor and it was fixed for about 2 months. Then started up again.

A new sensor this time, but fri. am had some tach drops. Went through it all again yesterday and a drive today showed no problems.

Did all the Bentley checks and found nothing wrong. R&R'd the fuse panel harnesses looking for a bad contact. Re-checked coil, sensor voltage and ECU function. If it continues to fault then it might be the ECU, or a bad new part.

We'll see. First one went 25 years so they should be robust.

 

[budgetzagato]

Pic of fuse...

The offensive little guy:

 

[zonker]

what amazes me is that the fuse did not blow. I wonder how melted it would have been if it was a 16A fuse??

 

[budgetzagato]

Maybe less so, since a 16A fuse might run cooler than an 8A fuse.

 

[zonker]

Maybe less so, since a 16A fuse might run cooler than an 8A fuse.

Ah yes. Never mind :mallet:

 

[Rupunzell]

More contact resistance related than fuse rating related.

One of the really bad things about those old european fused is the bare copper contacts or some used brass contacts. These tend to corrode resulting in poor contact with higher than acceptable resistance. This increased contact resistance sucks power from the connection and turns it into heat..

Do check the contact pressure and overall condition of these connections as they are problem prone.

Adding silver paste or other contact compound could help as this stuff is common in many power installations to prevent contact corrosion and help lower contact resistance.


Bernice

Maybe less so, since a 16A fuse might run cooler than an 8A fuse.

 

[Rupunzell]

Note the deformed end.. it is no longer the original length. This is caused the contact pressure to disappear increasing contact resistance and slowly cooking this fuse.

In time this could have gone up in smoke.


Bernice

The offensive little guy:

 

[budgetzagato]

And while I was looking...

And while I was looking I found this bad brown wire splice:

Obviously the connector had been bypassed and the brown wire poorly spliced. I cut this out and used a new union and my ratcheting crimpers for a solid connection.

As a result, the heater fan is more robust. Using the fan with anything else (wipers, lights) on no longer results in a glowing generator warning light. So, if you get the glow, check your brown wire connections for a loose, corroded or otherwise bad connection.