loom problems?

[MadMullet]

Hey users!...a quick (but i hope not overly complex) question from a Newbie..


We run 2008 f150s, and have recently developed some significant electrical problems. It appears that somewhere on the harness we have a dead short, or possibly a voltage regulator issue..i've run the multi meter over the loom and came up with the following results:

Battery voltage = 13.5 V
V at trim switch fuse block = V(batt)
V at isc/injector pump etc fuse block = V(batt) -4V
V at starter relay fuse block = .2 V

Main relay and both 50A fuses intact, as are both 20 A and the songle 30A fuse.

there is also a very low V at trim switch coupling

Have any of you had simliar issues with the loom, or have any helpful hints as to where(how?) to further isolate the problem?

Many thanks in advance


MadMullet aka Mikey the very upset guide

PS battery charge is optimal, and all leads/ cables etc have been inspected and are in fair condition..no corrosion/wear/chafing etc....

[99yam40]

What does V(batt) -4V mean?
13.5 - 4 = 9.5v? or -4 volts? seems that it would be easier to just state the voltage as it reads on the meter

A dead short would fry( melt) a wire/ cable and run the battery down.
Is that what is happening?

A high resistance in the wiring or a bad connection will drop the voltage without getting hot unless you are pulling a lot of current through it, I am guessing that is what you are trying to describe.

Do a voltage drop test from the battery on through the wiring and see where the high resistance is located. could be internal to the battery cable or cable end connectors.

[MadMullet]

Thanks for the advice Boss, (please excuse my poor description...i'm good at breaking em but not so crash hot at fixing em teehee )

It does indeed look like a dead short's draining battery power: the loom looks intact with no damage, as do the battery cables etc. (both the positive and negative straps going direct to the battery have had new terminals crimped on in the last weeks)
I might have to hit Yamaha up for the Workshop manual..

Cheers again mate

Mullet

[MadMullet]

Hey there Just-boss..

indeed batteries have been dying..... finally found the fault(s)..

Was a combination of bad positive battery strap, and also bad main earth strap going back to negative terminal from the block ( screw on block had flogged out and wasn't providing a good return path)

Phew!!



Many thanks for the advice aye

Mullet boy

[99yam40]

good to hear you have it fixed.

What is flogged out in normal words?

You said it was a dead short, did the positive short to ground somewhere or was it just bad connections?

[MadMullet]

Hey again Boss,

It ended up just being a bad connection(s).....wasn't a positive short to ground...(i hope)

the earth strap (just below the starter motor on the port side) had stripped the thread on the 8mm screw that connected the strap to the block...around 3-5 mm up the thread it had 'flogged out' (thread on the screw was rounded over) and seems that the increased play in the screw caused a bad earth (rectified with a lovely shiny new Stainless split washer for now)

I guess i should apologise for my (mis)use of jargon... we 'Orstralians' have a slightly differatn vernacular

Mullet

[MadMullet]

oh...and we can't type