Electrical Issues, Short or Open?

To the uninitiated, one electrical issue looks like the next.  'My lights quit working, can you fix it?' is a common question, or some variant thereof... I think its a short'.  I explain that I can't know until I check it over with test equipment, and ask the client if they did the basics and checked the fuses.  Usually that question gets a blank look for an answer...  

If you have never studied electricity, an automotive electrical system can look insanely complex with wires everywhere, switches in all sorts of places, various black boxes and connectors scattered everywhere, and to top it all off, nothing is labeled, which makes it even less friendly.  

All circuits in a car, motorcycle, RV or boat are all very similar.  You have a source of power- the battery or alternator or both, a fuse to protect the circuit, a switch, loads that are being powered (light, fan, etc...) and then the wires to connect it all up and conduct electricity from the source to the load and back.

All loads need two wires, one for the supply or negative side, one for the positive or return side.  Someone a long time ago screwed things up by saying that the positive side of a battery is the source of current, but that is nonsense and we need to kill that old confusing and useless paradigm.

Here comes the physics part of it... you have been warned.

Electrons form the outer, reactive shell of an atom of stuff, lets say metal in this case.  Those electrons, the source of the word electricity, carry a charge we arbitrarily call 'negative' while the inner portion of the atom carries a 'positive' charge.  It is these charges and the polarity difference that keeps atoms together, the positive and negative charges are pulled together by forces created by that polarity.  The weak electromagnetic force in physics is the direct result of these charges and  defines the interactions between those charged particles.

Extra electrons on the negative plates of a fully charged battery is what creates the negative charge on that terminal of the battery, and the lack of electrons is what creates the positive terminal.  Current physically flows from the negative side with excess electrons to the positive side with not enough electrons.  Voltage is considered to be the strength of the force created by the difference in the number of electrons stripped form the positive and dropped to the negative side during charging.  A discharged battery has the same number of electrons in both plates, therefore no voltage or current flow can happen.

A flow of electrons, bumped from one atom to the next on and on down the wire, is what we call electricity.  The voltage is the pressure driving the electrons down the wire, while current or number of amps is the actual measured number of electrons that are flowing in a given time past a given point.

In a standard circuit, the current flow is controlled by the resistance of the wires and load, and by the voltage pushing it down the line.  A fuse is rated for a specific flow of current through it, after which the wire inside melts and burns out stopping the flow of electrons through it.  If the resistance is too low in the circuit, the current goes up in direct proportion to the reduced resistance.  The same resistance can pass more current if the voltage is raised as well.  Either way, some safety device should be installed to prevent that over-current from damaging other components and wiring.

An open circuit is the simplest and most common form of failure.  It is also the hardest to track down.  An open circuit is simply one that no longer connects, thus current does not flow.  Somewhere in the circuit, something broke and no longer is connected and conducting.  It could be a switch that no longer switches, a burned out bulb or other component, or even as simple as an old fuse that finally blew from years of use near its limit.  Then there are the nightmare scenarios where there is a break in a wire somewhere in that massive bundle of wires and now we need to find it.  It could be broken in any of a thousand places along as much as 50 feet of wire in a bigger vehicle.  Like I said... nightmare scenario.  In these cases, I will often run a new wire with the old ones and power that load directly skipping the old wire entirely.

If two wires melt or rub through and touch metal to metal, the result is a connection that was not intended and usually results in over current.  This is a 'short circuit'  Literally, the circuit is too short to be healthy, it skips the load and has found a shorter path from one side of the battery back to the other side.  Hopefully the overloading of the circuit results in blowing a fuse, but if the circuit is one of the main power distribution wires, the fuse may be so high powered that it never blows, even while wires are smoking and catching fire.  

Replacing a blown fuse with one of a higher rating is always dangerous and stupid even for trained and experienced technicians running diagnostic tests.  Find the cause of the short, find it and fix it.  Then replace the fuse with the correct one and carry on.  Intentionally overloading a circuit by using a higher current fuse than the wire is designed for WILL result in a wiring fire.

A short circuit from improperly routed wires, or over-fused, under-wired circuits causing a fire is the biggest danger in self wired vehicles.  The car owner has the option to install stereo systems, additional lights and power sockets, inverters and appliances nowdays.  All these new and interesting electrical add-ons can be bought in the parts stores  or truckstops easily but have no decent instructions to educate the novice installer how to keep it safe.  

Helping your mechanic diagnose electrical problems starts by properly describing the problem.  If you can tell your mechanic that the windshield wipers have an open circuit and don't work, its very different from saying it has a short circuit in which the fuse blows every time and you smell burning plastic.  Correctly stating the problem is the first step to your mechanic not spending hours to determine what kind of fault is happening.  

Hope that clarifies a few things for ya... til next time...

MW outta here :-)




 

Help Your Mechanic Help You

First, happy August, its mid-summer up north here, mid winter for the southerners, I smell a change in the air for us all... Hows that for prophetic eh?

K, back on topic...

 If, and this is a big IF, you pay attention, are aware of changes in your reality, and you check over your vehicle and fluids on a regular basis, you are the best diagnostic tool your mechanic has in his or her toolbox.  You, as the owner/ operator are the first defense against vehicle breakdowns, the first one to recognize a problem or change and the best person to describe the problems as they arise. 

You know your vehicle, your mechanic works on it.  You know whats normal, your mechanic knows how it 'should' be.  You know how things change over time, what is different today from yesterday or last month, while your mechanic can say 'thats worn out and needs replacing'.  

When a problem arises or something seemingly changes, paying close attention and gathering information like a good investigator using all your senses to help your mechanic define and determine the problem can save you time, money, and machine downtime.

Being the best diagnostician you can be is crucial to preventing shistey mechanics from scamming you, having your vehicle hijacked by a mechanic who doesn't know diagnostics very well, or having the wrong parts changed.

When you can explain that the grinding, scraping noise appears to be coming from the rear, maybe right side, and only happens after letting off the brakes, the mechanic will know much more than when you only tell them that there is a noise in the car.  

A good mechanic, on a quick test drive with an experienced ear can track down simple issues, but you, as the driver, can help give crucial info that can speed up that problem finding.  

If you are driving along and feel a new vibration, what just changed?  What did you do just before it changed, what kind of road conditions changed, did you hit a big bump, a piece of road shrapnel, a pothole, puddle , patch of gravel or small animal?  

Is it a vibration, or a grinding sound?

Is the feeling of it coming from the seat under your butt, or from the steering wheel? 

Is it worse turning right or left? 

 Does it only happen when you accelerate? 

All the info you can offer to your mechanic, related or not, may prove to be the important missing piece to determining cause and getting it fixed quickly.

The other day, a client called me kind of scared for her vehicle and family.  When she called me, she could only say that the car was bucking and shaking at about 15mph, not accelerating beyond that.  I said I would check it out first thing in the morning, and not to drive it anymore tonite now that she was home.  I immediately suspected fuel pump, fuel filter, wet ignition, or ECM sensor failure.

Upon complete diagnostic inspection to check everything and a test drive- all of which took a bit over an hour- I concluded that it was all in the automatic transmission.  How you ask?  

The truck fired right up, and OBD2 codes came up irrelevant.  During the test drive I noticed I could change the behavior of the vehicle with the shifter.  Starting out in D it would clunk, then buck, shudder and not accelerate well at all.  If I shifted it into L and followed engine RPM shifting like with a standard transmission, it would clunk only once and accelerate normally.  Still not a happy transmission, but noticeably better treating it more like a manual.  After asking a few questions, I concluded it is time for a transmission fluid & filter change and flush: hope that fixes it.  It may not tho... it may be a shredded transmission, may be too late already for the price of over 10 years of no fluid changes.

Taking the time to determine what changes the behavior, what does nothing and is unrelated, and what might seem unrelated are all aspects of putting on your investigator hat and listening, feeling, observing  and noting what changes, what causes what, what seems to be causal or corollary versus what seems coincidental.  Even mentioning that the fluid has not been changed since you have owned the vehicle is valuable info to share with your mechanic.  Collect all the info you can to give your mechanic the best chance to properly diagnose the problem quickly and effectively.

When something changes, or some new noise or malfunction comes into being, ask yourself these questions:  

   1- Does it change when I...? (turn the steering wheel, press the brakes, run over bumps in the road, turn on the lights or blower, etc...)
 
   2- When did it start? (after driving thru a puddle, taking a hard left turn to avoid a collision, adding questionable fuel from a backwoods fuel station, or cleaning the engine, etc...)

   3- What are the noticed symptoms?  (it grinds when I..., it shakes when..., the car won't stay straight and pulls right hard when I hit the brakes, etc...)

When you roll into your mechanic, a good description of a problem might be:
  
 'Hey Bob g'mornin.  Thanks for the emergency checkup, Heres a breakfast burrito from that little cafe up the street.  Hey, so I drove through a fairly deep puddle at 30 mph yesterday and now every time I hit the brakes the car immediately pulls really hard to the left.  There is a harsh grinding sound from what sounds like the left front wheel and the steering wheel shudders when I take a left turn and hit the brakes at the same time... Oh, and it gets really bad over 40 too.  I know you just did the brakes and they have been fine until the puddle incident.  I don't feel any other clunking or vibration, and the car feels stable and steers fine without the brakes engaged'

You could also simply say 'It makes a grinding noise' and pay the mechanic to figure it out while you wait and pay and pay and wait.

The burrito scenario ( Yes, your mechanic will be grateful for a hearty snack- I like coffee and chocolatey stuff myself ) with the additional information yields much quicker results for diagnosis and repair. 

This scenario gives the mechanic several places to start with diagnostics and with a quick test drive can probably determine the problem.  That added description required nothing but simple observation skills on your part, no technical knowledge at all.  This procedure of observation is simply noticing when things change, what they changed to and any other connections that seem valid.  

To Tom & Ray Magliozzi; AKA Click and Clack, the Tappet Brothers; who always kept it lively, taught me oodles about customer service and always got people to make the silliest sounds trying to describe the problems... 

Thanks guys, ya goofy buggers ya, lotsa laughs!!. 


And yes, we mechanics do get some harmless but entertaining chuckles at the expense of the lay persons using such funny noises to describe the problem their machines are experiencing.  We love it, it makes our day to hear it, thanks to you as well.  

:-)




Til the next round... MW out n zoomin...





 

    

Embracing the Clutch: Tips and Hints

Have you, do you currently, or do you want in the future to drive a standard, manual, stick shift transmission? If so, this one is for you.  

There are some distinct advantages to a manual transmissions, and a few minor drawbacks too.  Its no secret among my friends and clients that I really don't like automatic transmissions, but I do recognize they have their place in some applications.  I get great clutch life from my vehicles, and great performance on the street or off road.  I prefer my vehicle with a third pedal, thanks, and here are my basic rules to getting the most value from that third pedal.  

There are many benefits to owning and driving a manual transmission vehicle.  Being able to more quickly adapt to changing driving conditions with forethought instead of only reacting after things change as an automatic transmission does, more accurate and fine control of acceleration and deceleration, and a more fun and visceral connection to the road and machine are the primary reasons people choose to own a manual transmission equipped vehicle.  Not to mention the interaction of human and machine helps to relieve road weariness and prevent driver fatigue as quickly. 

Manual transmissions are simpler in many ways and have nowhere near the number of moving parts as an automatic.  Manual transmissions are generally tougher, longer lasting, easier to repair and change fluids, and also lighter weight. An automatic transmission wastes fuel through slippage unless it locks the torque converter between shifts whereas a manual transmission is locked to the engine when the clutch pedal is released, assuring that all the power from the engine goes to the wheels not wasted as heat from fluid shear.

The purpose of the clutch is to allow a smooth transition from stopped to moving by slipping slightly between the engine, spinning  many hundreds of RPM even at idle and the transmission shaft connected to the wheels on the ground, which are all completely stopped.  The clutch absorbs the difference in speed between the engine and transmission by slipping and wasting energy as heat.   Any time the clutch pedal is in the middle of its throw, neither fully in and released, free to spin; or out and completely locked together as one unit spinning together, the clutch is wearing out and being damaged by heat.

So, the first rule of a clutch pedal is get your foot off of it. Period.  No exceptions.  Either the clutch pedal is on its way in and held there, or on its way out, but it is not a foot rest. Keeping any additional, even slight and gentle, pressure on the clutch pedal results in faster release bearing wear, slippage of the clutch, and increased heat in the clutch housing.  

Next rule:  Keep the engine revved only the minimum needed to obtain smooth operation and no higher during initial engagement and startup in first gear.  Most automotive engines produce smooth power around 1000 RPM and this is generally an excellent engine speed to start off at.  A little more throttle may be necessary on a hill or accelerating hard into traffic, but overall, the lower the speed of the engine during startup, the better for clutch longevity and eliminating heat build up. 


The higher the engines speed during clutch release, the more energy is wasted as heat in the clutch housing due to slippage and friction.  This heat buildup can ruin engine and transmission seals from long term overheating and can drastically shorten the life of the clutch from glazing and polishing of the surfaces involved. 

The way I explain starting from a stop to rookie drivers of manual transmission is like this: I recommend getting your left foot off the clutch as quicky and smoothly as possible without over-revving the engine while eliminating bucking or lurching.  Thats it...

I teach newcomers to manual transmissions to start the vehicle nice and smooth on flat pavement with no accelerator pedal use at all.  Get the car up and rolling with the clutch pedal all the way out as quick as possible with no accelerator use whatsoever.  None, No go pedal.  Just pull your right foot up to the seat and use only your left foot to engage and release the clutch.  Get as smooth and fast as you can, and when you can do that fast and easy, then you can add a bit of throttle to make the transition faster yet.


When shifting gears, the rule is the same as starting out, smooth and fast.  Shifting should be a much faster transition of clutch pedal position than starting from a stop.  Clutch in; shift gears; clutch out- done.   That fast, that smooth.  No bucking or lurching or whiplash.  Smooth like velvet.  

The shock to the system from too rapid a release of the clutch can break parts in the drive systems, can ruin rubber or plastic mounts, tear tires or destroy shocks, struts, bearings or driveshafts.  Not to mention giving your passengers a lifetime of neck pain.  Again, the keyword is smooth.  

Over revving and under revving of the engine are another point worthy of touching on briefly.  Every engine has a powerband, a range of engine speeds that produce maximum peak horsepower.  The 'wider' the powerband, the greater the range of RPM that the engine can produce power most efficiently and thus the greatest acceleration.  Generally speaking, for engine longevity, most situations dictate keeping engine RPM in the bottom 1/3 of the powerband when not accelerating.  Each engine is different, but having 2/3 or more of the overall power the engine is capable of at the touch of the skinny pedal is wise in most conditions. 

Over-revving causes unnecessary and rapid engine wear and wastes fuel.  If an engine will produce the power to accelerate in a higher gear, upshift.  If you shift into a higher gear and lose speed immediately, downshift and accelerate rapidly to a higher speed to prevent speed loss again when you aupshift.  If need be, slow down and stay in a lower gear if the engine cannot make enough power in the higher gear.  Its a 'feel' thing.  Let the engine work where it is happiest.

If you need to accelerate, don't be afraid to use the higher RPM range of the engine, but if you are just cruising along, use the highest gear possible that allows the engine to run smoothly without chugging.  If you push the accelerator down and the engine speed does not increase immediately, you are in too high a gear for the speed and you need to downshift to a lower gear.  This is referred to as 'lugging' the engine and causes overheating of valves and pistons and rapid wear on the piston sides and skirts as well as added bearing damage.

Downshifting early before climbing or descending a hill is a wise tactic as opposed to letting the speed change significantly and then expending additional energy as fuel or wasted in the brakes to bring the vehicle back to desired speed.  If you upshift out of 3rd gear into 4th at 80kph (55mph)then you can downshift onto third gear at roughly that same speed.  Never downshift into a lower gear at a speed significantly higher than you would upshift out of that gear when accelerating.  This action can over-rev an engine and potentially cause severe damage.  

This article turned out longer than I thought it would be, but I think I covered all the important points.  I hope it clears up some misconceptions and increases the life and reliability of your clutch and other related parts.  Also, hopefully I converted a few drivers away from wasteful automatics back to simpler, cheaper, longer lasting manuals.  After operating a manual transmission for a few hours, most people are comfortable and capable and no longer need to think about the process.  So don't be afraid of that third pedal, make use of it and enjoy it.  Relish the ability to interact as a driver instead of being chained to a computer that tries to think for you, keeps you passively bored, and takes away your control and enjoyment of the driving experience.

Happy driving happy drivers...