Electrical Harness

My wife's '03 325 had total engine failure twice, soon after she bought it
(New).

First time @ the dealer, they couldn't find the problem. Second time, they
realized a harness was mis-routed and overheated, thus changing capacitance
and interrupting the communication with the onbaord computer.

Rerouting the harness fixed the problem, and there hasn't been a recurrrence
since.
 >> Stay informed about: Electrical Harness 

"Dave Plowman (News)" <dave RemoveThis @davenoise.co.uk> wrote in message
news:4ff64e431adave@davenoise.co.uk...
> In article
> <6d3d2302-d9db-41bb-8094-acd8425b2198 RemoveThis @y21g2000hsf.googlegroups.com>,
> <afcbfcc RemoveThis @hotmail.com> wrote:
>> I have a 2003 BMW 325xi. I know almost nothing about cars.
>
>> I took my car to the dealer last week because the engine was riding
>> very rough; the dealer diagnosed the problem as a cylinder not working
>> (due to issues with a coil).
>
>> A few days after I left the dealer, the problem came back, and I took
>> the car back to the dealer again. This time, they said that there is
>> a short in the electrical system and that they will need to replace
>> the electrical harness to fix the problem. They said that it could
>> take them 4-5 hours to replac the harness.
>
>> My questions are:
>
>> - Does this sound right?
>
> I suppose it could be. Although a short is most unlikely. A break or poor
> connection is more common.
>
>> - What is en electrical harness, and where is it located?
>
> Wiring (obviously) goes to every electrical part of the car and this is
> referred to as the harness or loom. It consists of many sections which
> plug together. The engine electronics will be one of those sections and
> it's that which will be replaced.
>
>> - What does replacing an electrical harness entail? WIll the dealer
>> have to remove my dash, carpeting, or door panels?
>
> In this case I'd think not.
>
>> Thank you for your help.
>
> Unless there is severe damage to that part of the wiring loom (which is
> unlikely) a competent auto electrician would normally repair it. The fault
> is most likely at a connector which can be replaced. But most garages
> don't have competent auto electricians - you'd need to find a specialist.
>
> In the UK the labour time you've quoted would cost over $1000 at a dealer.
>
> The ECU should be giving a code which identifies the fault and a
> competent auto electrician should be able to test and repair that section
> of the harness pretty quickly.
>


To expand a little bit on what Dave said, the harness in question here
should reside entirely within the engine compartment, but there is a very
small chance (some makers do this part differently, which is my hedge here)
that the harness they are focused on terminates behind the glove
compartment, and therefore enters the passenger compartment.

By your description (the OP, not Dave) the dealership found a defective
coil. In prior years -- engine designs -- there was one coil and a wire
leading from the distributor to each spark plug, you may recall seeing a
batch of heavy black wires on other kinds of engines. Your BMW uses an
individual coil for each spark plug. This is arguably a more costly design,
but is also a more efficient design and is worth the cost-up. In any case,
the coil has to be told when to discharge in order to create the spark
needed by the engine. Your roughness was the result of at least one coil not
firing (discharging) properly. The initial diagnosis was the coil had
failed, the current diagnosis is that the control to the coil is failing.
This control comes from the harness that they want to replace.

The harness is not likely to be shorted as it is to be open.

I think they don't have a clue and are simply guessing at what to do next.
What _I_ would do next is to swap a couple of coils around to see if the
problem moves. If the #3 cylinder is misfiriing -- the engine gives a
trouble code that tells them which cylinder is not working right -- then
swap the coil on this cylinder with one on a different cylinder and keep
track of which one was swapped. Assuming the engine contiunes to run poorly,
the trouble code should move to where the coil went IF the coil is the
problem, or should remain on the #3 cylinder if the wiring is the trouble.
This is a simple test that should take about 10 minutes to set up and
perhaps a minute or two of observation.

(Sorry, I think I swapped the terms cylinder and spark plug. People that
know this stuff will understand the swap and it isn't a problem. For the
novice, a misfiring spark plug and a cylinder that is not working are the
same thing within the confines of this problem ... )
 >> Stay informed about: Electrical Harness 

<afcbfcc DeleteThis @hotmail.com> wrote:
>I have a 2003 BMW 325xi. I know almost nothing about cars.
>
>I took my car to the dealer last week because the engine was riding
>very rough; the dealer diagnosed the problem as a cylinder not working
>(due to issues with a coil).

Okay, this makes sense. What he saw was that there was no spark on
that cylinder. So they replaced the coil (without actually diagnosing
the problem carefully).

>A few days after I left the dealer, the problem came back, and I took
>the car back to the dealer again. This time, they said that there is
>a short in the electrical system and that they will need to replace
>the electrical harness to fix the problem. They said that it could
>take them 4-5 hours to replac the harness.

Probably not a short, probably a bad connector on the harness. These
things do fail.

>My questions are:
>
>- Does this sound right?

It does.

>- What is en electrical harness, and where is it located?

It's any bundle of cables. I assume that the one that is the problem is
between the ECU and the coils. But there are hundreds of premade wiring
harnesses in one of those cars.

>- What does replacing an electrical harness entail? WIll the dealer
>have to remove my dash, carpeting, or door panels?

I don't know where the ECU on your car is, but if it's in the glove
compartment, it could be a bit of a pain.

I suggest you take the car to an independant mechanic and have him FIX the
wiring harness rather than just replacing the whole thing as a unit. It
should be a lot less expensive.

While you're at it, have him pack all the connections with dielectric grease.
This will keep air, water, and road grime from getting into connectors and
causing more problems in the future.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
 >> Stay informed about: Electrical Harness 

In article <wxlOk.55595$Zc.4857@newsfe09.iad>,
JimmyG <jimmypotts DeleteThis @yahoo.com> wrote:
> First time @ the dealer, they couldn't find the problem. Second time,
> they realized a harness was mis-routed and overheated, thus changing
> capacitance and interrupting the communication with the onbaord
> computer.

Crikey.

--
*'Progress' and 'Change' are not synonyms.

Dave Plowman dave DeleteThis @davenoise.co.uk London SW
To e-mail, change noise into sound.
 >> Stay informed about: Electrical Harness 

<afcbfcc RemoveThis @hotmail.com> wrote in message
news:6d3d2302-d9db-41bb-8094-acd8425b2198@y21g2000hsf.googlegroups.com...
>I have a 2003 BMW 325xi. I know almost nothing about cars.
>
> I took my car to the dealer last week because the engine was riding
> very rough; the dealer diagnosed the problem as a cylinder not working
> (due to issues with a coil).
>
> A few days after I left the dealer, the problem came back, and I took
> the car back to the dealer again. This time, they said that there is
> a short in the electrical system and that they will need to replace
> the electrical harness to fix the problem. They said that it could
> take them 4-5 hours to replac the harness.
>


Your car is OBD II (On Board Diagnostics, Level 2) compliant. This means
that the Check Engine light ought to have come on due to your reported
problems. the dealership's service department should have pulled codes for
you and put them on the service report. We need those codes to offer
assistance.

The codes for the failed coils should be in a range of P0300 through P0306,
where P0300 is a general malfunction and P0301 through P0306 are specific
cylinder misfires, where 1 through 6 specify which cylinder(s) misfired.

Here is a complete list of OBD II Codes, (don't be concerned that the title
of the page specifies 1996 through 2003)

http://autorepair.about.com/od/obdcodedatabase/a/OBD_1996_year.htm
 >> Stay informed about: Electrical Harness 

afcbfcc RemoveThis @hotmail.com wrote:
> I have a 2003 BMW 325xi. I know almost nothing about cars.
>
> I took my car to the dealer last week because the engine was riding
> very rough; the dealer diagnosed the problem as a cylinder not working
> (due to issues with a coil).
>
> A few days after I left the dealer, the problem came back, and I took
> the car back to the dealer again. This time, they said that there is
> a short in the electrical system and that they will need to replace
> the electrical harness to fix the problem. They said that it could
> take them 4-5 hours to replac the harness.
>
> My questions are:
>
> - Does this sound right?
> - What is en electrical harness, and where is it located?
> - What does replacing an electrical harness entail? WIll the dealer
> have to remove my dash, carpeting, or door panels?
>
> Thank you for your help.
>
> --AJ

Did they actually REPLACE coil(s)? My 2004 330 started running poorly
one day, took it to the dealer where they said there was a recall of a
number of cars due to coils with manufacturing defects. They replaced
all six and no problems since. I assume your dealer checked the recall
list?

lj
 >> Stay informed about: Electrical Harness 

in article
6d3d2302-d9db-41bb-8094-acd8425b2198.TakeThisOut@y21g2000hsf.googlegroups.com,
afcbfcc.TakeThisOut@hotmail.com at afcbfcc.TakeThisOut@hotmail.com wrote on 10/29/08 6:49 PM:

> - Does this sound right?
> - What is en electrical harness, and where is it located?
> - What does replacing an electrical harness entail? WIll the dealer
> have to remove my dash, carpeting, or door panels?


nope ... unless it is warrenty.

then fine ... swap out the harness if they want.

otherwise ... big NOOOOOO.

also ... your Dealership is making poor mechanical decisions to make more
money from you ... IMO of course.

There are lots of fine minds here, well educated, learned as to the subject
matter. As you read on ... you will find out more concerning your Dx and
the solution possiblities.

Your BMW certified mechanic will sort this out ... not a problem.

If your BMW certified mechanic owns his own shop ... and not from the
dealership you will only have him or her to talk to.

I think cause your dash lights are not going off ... like the check engine
light ... they might be making this recommendation ... if they are pulling
proper codes from the computer and such.

Still ... just repair what is broken in the harness if it is isolated.

If the harness, wire loom is burned and smoking and fused ... well then
there is a bigger problem going on.

Cars are like watches with thousands of parts ... and about 4% of the time
the parts just do not fit and work properly.

In California we have "Lemmon Laws" ... as cars, trucks, conveyances are so
important ... that we want a good one ... that comes out 96% of time easily
enough.

The Car Manufactures know about this manfacturing problem and can not
eliminate the human element that makes for the human variable in what it
makes sorry to say ... so there are lemmon laws in my state.

Get a second opinion.

Your dealership ... maybe on the right track ... but with the poor way they
handled the first problem supposedly .. they are still working the solution
poorly and at your expense.

Slow economy ... watch out for dealerships as they have lots of overhead to
protect with sales and all ... so the cash cow is you or who ever walks into
the door for repairs as they can take advantage of them.

IMO again.

sumbuddie wear blind sea


 >> Stay informed about: Electrical Harness