Earth by ECU Melting

P

pugtk

Sunday Drivers
Hi All,

So had my car mapped up with ap performace, went well all day.

So brought the car home, hoped in for a spin and a heap of smoke started to come from the ecu area.

So on inspection the earth beside the ecu had melted back upto where it joins in the loom.

Any common reasons for this?
 
No never heard if that before did you do anything with the battery ? Also check your leads on the battery and the alternator in case it?s over charging
 
Could also be a bad, loose earth strap between chassis and block?

D.C is very susceptible to high resistance caused by corrosion, poor connections etc.

A new strap between battery and chassis, chassis to block can definitely do no harm,
Current could to be finding it?s way back through ECU earth as it has no other path.

Think we all overlook the age factor on cables, around 80% of wiring faults they reckon are wire and connection problem as opposed to parts.

Hope this helps


Sent from my iPhone using Tapatalk
 
20191006_121331_ec2a5d1015340141aed010104a01038a144fe0d9.jpg


So its the red wire earthed by the ecu.

Also the second time to melt.
 
scoobysub said:
No never heard if that before did you do anything with the battery ? Also check your leads on the battery and the alternator in case it?s over charging
Click to expand...

Not overcharging, all earths in the engine bay are ok.

No loose battery cables either
 
HawkAl said:
Could also be a bad, loose earth strap between chassis and block?

D.C is very susceptible to high resistance caused by corrosion, poor connections etc.

A new strap between battery and chassis, chassis to block can definitely do no harm,
Current could to be finding it?s way back through ECU earth as it has no other path.

Think we all overlook the age factor on cables, around 80% of wiring faults they reckon are wire and connection problem as opposed to parts.

Hope this helps


Sent from my iPhone using Tapatalk
Click to expand...


Food for thought, I would have been under the impression for a earth to melt, 12v would have needed to pass through it
 
The same current (measured in amps ) therefore the same heat will be passed through a positive or negative cable irrespective of voltage.

Could be well worth borrowing a D.C clamp meter to see what current is actually flowing through the red earth cable, a multimeter set to D.C amps will work either by putting it in series between the chassis and cable lug.

I?m as intrigued as you are to see what the problem is!


Sent from my iPhone using Tapatalk
 
Very unusual for a red factory wire to be an earth are you sure it?s an earth . Have you any rewireing in Ecu ? but red to earth I?d say is wrong but again someone with more wiring experience might know better .
 
scoobysub said:
Very unusual for a red factory wire to be an earth are you sure it?s an earth . Have you any rewireing in Ecu ? but red to earth I?d say is wrong but again someone with more wiring experience might know better .
Click to expand...

It was originally black, I was having issues with poor lights etc a year ago and I found this same wire melted.

I replaced all the melted wire upto the point it joins into the main loom.

But I don't want to change it again with out getting to the root of the problem this time.
 
You need a pin out and wiring diagram of the your car to get the proper location of that wire as something is not right :thumbsup:
 
Even if you get a budget multimeter you can check the current flowing through the earth by removing the lug from the chassis and place the meter in series.

You can record a change once you start to turn on lights, heater etc.

May be of help, . .also on a different note handy way of checking a parasitic power drain if a battery is discharging too quickly once left idle for a few days.


Sent from my iPhone using Tapatalk
 
HawkAl said:
Even if you get a budget multimeter you can check the current flowing through the earth by removing the lug from the chassis and place the meter in series.

You can record a change once you start to turn on lights, heater etc.

May be of help, . .also on a different note handy way of checking a parasitic power drain if a battery is discharging too quickly once left idle for a few days.


Sent from my iPhone using Tapatalk
Click to expand...


So whats the next step if there is a current going through the earth? Also there should be no current through an earth? right?

Apart from looking for a short/visible wire damage somewhere along the way. Thats about the height of my wiring knowledge

Where would I get a wiring diagram for a version 4 ?
 
You will have current through your earth but I believe it is excess current which caused the wire to melt.

If I were to guess from pictures I would say max current flow should be less than 10 Amps.

Turning on ancillaries and seeing what causes the spike would be a good start.

The wire could also be too small for an additional item that was added to the loom or used to renew an earth from a headlight etc.


Sent from my iPhone using Tapatalk
 
You must log in or register to reply here.
Back
Top