Ha Ha...I titled this post "SCARY Tech" because nothing seems to invoke as much fear and superstition in seasoned car folks than the prospect of diagnosing ans solving a sudden electrical problem! I've seen guys who wouldn't think twice about chopping a top, Z-ing a frame or rebuilding a Torqueflite practically go to tears over some sudden mysterious electrical glitch! It needn't be so intimidating, folks...and I hpe I can help you to view your car's electrical system with less doubt, fear and apprehension after you read through this post! Now, as always, a short disclaimer here! I can't BEGIN to cover every possible problem that you may encounter, but I will attempt to illustrate my approach to solving the problems I've encountered in my experience as both a professional and a backyard mechanic. I will cite some examples and walk you through the steps I took to solve them, and of course, this post will be open to replies from others who can share similar tips and examples. After you see how these things crop up and get solved, you won't tremble with fright the next time something goes awry in your car's wiring! BEGIN WITH BASICS The battery is the heart of your vehicle's electrical system. Without it, you won't have any juice to get it started, and no current to trace through the wires! A visual check of your battery is a great place to start this discussion! Look for cracks in the plastic case or evidence of leakage. Damaged batteries pose both an environemtal and a health risk, as well as being extremely corrosive to any metal the acid may reach. Safely dispose of any damaged battery! Next, check the cables and the connections. Whether you run a top post or side post battery, you want the cable ends to be clean and tight. Loose or dirty connections at the battery are responsible for more no-start, charging and electrical headaches than you may realize! It's a point of maintenence that you should keep on top of during regular service intervals. Inspect the cables themselves. If they are frayed and turning green, then replace them at once! Old cables increase the resistance in your car's electrical system and can create starting and charging problems...sometimes intermittently! When installing a new battery, take the time to clean the tray area below it. Remove any scale, rust, debris, or lost bolts or tools that may have collected there! Putting down a piece of old rubber floormat cut to the size and shape of the battery is also a good idea. Make sure that you have some sort of proper hold-down to keep the battery securely in place and to stop it from bouncing around, tipping over, or rubbing on something that could wear through the plastic case creating a hazardous acid leak. When hooking up your cables, apply a thin coat of No-Oxide or similar conductive grease to stave off corrosion and promote a good, long lasting connection. Use a voltmeter to test your battery's voltage. A typical 12 volt battery should read at least 13.2 volts at rest with no draw placed upon it. (If the engine is running, and your charging system works, you should be reading around 14 volts or so). If you have a load tester, you can test your battery at home, but most parts joints will do this for you free of charge if you bring a suspect battery to them. Most of today's batteries are the "maintenece free" type, with sealed caps, but some still require periodic checks to determine that the water level is up to par. Distilled water works best when topping off your battery's cells, but tap water will work out fine if you need to fill it that way, too. THINK STUPID! Now that we've covered making sure that your battery is installed and up to snuff, we can talk a little bit about diagnosis and repair. The Human Mind can create the wildest and most complex scenarios when pondering the possible causes for a newly discovered problem, and this can lead you on all sorts of wild goose chases! My tip to all is to "Think Stupid" when looking for an electrical problem, because the culprit is likely something...STUPID! Start with some common-sense tactics. What is the nature of the problem? Not charging? Won't start? Killing the battery after sitting a while? Something in particular not working? A fuse keeps blowing? Once you've determined just what the SYMPTOM is by putting your problem into one of the above catagories (or another of your own), you can think through the possible CAUSES that might lead to such a condition. I'll throw the "Think Stupid" phrase at ya as we go further into this journey of electrical quagmire! STARTING We can't very well worry about diagnosing OTHER problems, or even about getting to the party store before they close if the car won't START to begin with! If you turn the key, and the engines cranks very slowly or not at all...you are going NOWHERE, Buddy! Once more, back to the stuff I mentioned about the battery! Check those cables...are they tight and clean? I've gotten more than one stranded vehicle started by working the cable ends on the terminal post a little by hand...making a better connection and getting the engine fired. Think Stupid! Listen to what the car is doing (or NOT doing!). Does it click when you turn the key, but not crank? Do the dash lights go dim when you turn to "start" but nothing happens at the starter? Or does it do NOTHING at all? If nothing happens at all, and other electrical items such as the headlights work okay, then you have a break in the switcth-to-starter circuit somewhere. Could be a bad wire, a bad relay or solenoid, or a bad ignition/starter switch. Try jumping the relay or solenoid with a remote starter switch or (gasp!) a screwdriver blade. If the engine cranks normally, then you have a bad switch, or a break in the wiring somewhere most likely. If jumping the relay or solenoid engages the starter, but won't turn the engine over, check for something binding the engine up (hydrolock, tossed rod, siezed, etc!) or a bad starter may be to blame. Many times, a sharp rap on the starter casing will get you fired up one or two more times. Off road guys know this trick and have used it on the trails to get back to civilization without walking! With a hammer directly, or through something solid like a long 1/2" drive extension, deliver a serious blow to the starter housing and try it again. I have rarely failed to get at least ONE more "emergency start" out of a dying starter this way! Another thing that may cause this problem is a faulty or mis-adjusted neutral safety switch (if the vehicle is so equipped). Try wiggling the shifter (automatic) or pushing a little harder on the cluch pedal (stick shift). A buddy of mine went through the fun of replacing the starter on his V8 Mustang II only to find a sloppy netral safety switch to be the REAL problem. Think Stupid! Again...people will overlook STUPID problems in this area. A high school buddy of mine put closed chamber 429 heads on his 460 block with domed pistons. Cranked down the head bolts and went to fire it up. He spent two days and lots of money buying starters and relays, bigger battery and such before giving me a call. I looked at the crooked heads and the gap between the head and block and told him hist heads were cranked down onto the piston domes and keeping the motor from turning! An extreme case, but a classic STUPID mistake mis-diagnosed as an electrical problem! CHARGING By all means...run right out and buy a new alternator or generator when you experience a charging problem! Ha Ha Ha...no, that's NOT the way to do it...but it's what most folks often DO! Start with the basics...and (yep) THINK STUPID! To begin with...the alternator or generator has to TURN to work. I've been shocked to see people scratching their heads or buying expensive parts when they failed to notice that the belt had broken or jumped off of the pulley! Think Stupid! Even if your belt IS on, it may not be doing it's job. If it is excessively old or "glazed", it may be slipping enough to affect your alternator or generator's output. Inspect the condition of the belt and replace it if it looks suspect. Another consideration is belt tension. A loose belt won't grip the pulley properly and will fail to spin the charging device at the proper speed. Look for about 1/2" deflection between pulleys to determine proper tension. On some engines, ESPECIALLY Olds V8s of the late 70s and early 80s, you will notice that only a small portion of the pulley's circumfrence is actually in contact with the belt due to accessory layout. Good belts properly adjusted are ESSENTIAL to make these engines charge! They can slip enough to cause a problem without being audible...so be carefull! (Some models use a double grooved pulley and two belts to help solve this issue.) Once you've established that the charging device is indeed TURNING at the proper rate, you can look further into your problem. Checking the voltage output at the battery cables with a voltmeter should give you an indication of whether or not you're charging. (Should read around 14-14.5 volts as stated earlier). Another test that works "in the field" is to disconnect the battery cable with the engine running. In theory, if the engine stays running, then you're charging. If it stalls, then the charging system is putting out NOTHING and you're running off of the battery. Although this test works okay as a general field test for us 4x4 guys, it only really shows you whether or not your charging system is putting out enough juice to operate your ignition system. I've seen vehicles that would run with the positive cable disconnected, but were not charging well enough to operate headlights or keep the battery charged. Sometimes you will get warnings...such as a 'charge' light that comes on dimly. I've seen many GM cars with internally regulated alternators do this, and it generally indicates that one diode has failed within the alternator, and you're CHARGING, but not to full capacity. The beauty of internally regulated alternators is that you replace the regulator and the alternator in one shot. It also simplifies wiring and reduces the number of seperate components that could potentially fail and need replacement. On cars with external voltage regulators, ALWAYS CHECK THE HARNESS THAT PLUGS INTO THE REGULATOR! This is a good practice with ANY electrical component, but I have seen far too many people waste money buying a battery, alternator, and a regulator before realizing that one of the wires in the regulator harness was broken, pulled out of it's plug, or corroded to the point of not making contact! Once more...THINK STUPID...and eliminate the silly things BEFORE spending money throwing parts at the problem! Another "field test" that my old off road buddies used to try was to touch a wrench or the tip of a NON magnetic screwdriver to the back center portion of their alternator. If there was a magnetic pull, the alternator was thought to be good. Hey, I don't know how much truth there is to THAT one, but many guys insist that it works as well as pulling the battery cable! SHORT! Some of the most frustrating electrical problems to trace for many mechanics are short circuits, or current draws that drain the battery when the vehicle is parked. You can produce a short anytime a positive wire is allowed to contact ground...either through burned off insulation, metal rubbing on the wire, or other possibilities. The circuit that is shorted will fail to work, though...helping you trace your problem. Obvious things to look for include wires passed through the firewall or other sheetmetal without rubber gromets, wires that have come into contact with headers or exhaust manifolds, or components that have been damaged through vibration or impact. My first step when tracing a short is to disconnect the positive battery cable and hook a test light acroos from the cable end to the battery post. (Be sure all accessories are turned off and the doors are closed, and any underhood courtesy lamp bulbs are removed. If nothing is creating a draw, the light won't be lit. If something IS pulling current when it shouldn't be, the light will be illuminated. (You can use a voltmeter for more accurate results, but I've always been able to read what the light tells me very well!) If the test light is lit real BRIGHT, then you have a BIG draw somewhere. If it's dimmer, the draw is in a circuit that draws less current. I once had to find a dead short on a Ford Ranger for a customer. It was draining the battery in just a short amount of time, and really lit up my test light, indicating a hell of a draw somewhere. Well, thinking stupid lead me to reason that the only circuits that draw that much current at all times (potentially) are the headlights, brake lights, horn and cigarette lighter in most vehicles. A quick check showed me that the headlights, horn and brake lights worked fine, so I reached behind the dash and unplugged the hot wire to the cigarette lighter, and the test lamp went out! Upon removing and inspecting the lighter socket, I found a nickel welded across the contacts...producing the dead short! Thinking Stupid had prevailed...it wasn't some bizzare, complex problem...it was something stupid! By trying out various suspected circuits until you find a component that doesn't work, you can track down most shorts quickly. Once the non functional component is found, it can be checked, along with it's fuses and wires running to it, as well as any switches involved in the voltage path to said component. Intermittent shorts can be far more difficult to locate, because they seem to come and go. Let me share two examples of how Thinking Stupid helped me quickly solve intermittent shorts for customers. In one case, my partner had a Crown Victoria running in his stall with the radio going, doors open and visors pulled down with the vanity mirrors lit. The complaint was a frequently blown fuse. The items controlled by that fuse were the radio, courtesy lamps, door dinger and vanity mirror lights according to my partner. After sitting in the car for about 15 minutes, he called me over because the fuse had not blown yet. He hopped out and I hopped in. Thinking Stupid, I looked up and noticed that the owner favored driving around with the inner portion of the sunvisor unhooked...letting the visor (loaded up with coupons, papers, and other clutter) shake and vibrate as the car went down the road. I reached up and smacked the visor, instantly blowing the fuse and told my partner to insulate the wire inside of the visor that had been rubbed through due to the bouncing visor, and to advise the customer to keep the end clasped in it's holder! Another case was a friend's 4x4...the charge light would come on while driving, then he'd hit a bump and it'd go out. To me, that meant a wire was being bounced around and grounding out somewhere. It didn't take but a quick peek under the hood to spot a dangling wire near one header with the insulation burned away. Touching the wire to the header with the engine running lit the charge light...pulling it off made it go out! Thinking Stupid worked AGAIN! I wrapped the melted wire with electrical tape ans zip-tied it safely out of harm's way. Problem solved! Of course...some dead shorts can be more than just a pain in the ass...they can lead to smoke and fire real quick! A little common-sense when wiring or servicing the wiring on your vehicle will go a LONG way towards preventing these disasters... Insulate EVERYTHING. Use tape, shrink tubing, plastic wire looms, gromets, zip ties...whatever you have to use to keep wires snug and away from sharp metal or hot surfaces, or moving parts. Neatness in your wiring habits doesn't just LOOK nicer...it helps prevent glitches and dangerous shorts as well! When wiring a vehicle from scratch, you have the unique opprotunity to engineer a smart and trouble free electrical system that will be easy to trouble-shoot should the need arise for you, or someone else down the road, if you choose to take the extra time and do it RIGHT! (It's SO much nicer and simpler to diagnose electrical problems in a vehicle that was wired well and neatly in the first place, than to try and track miles of same color wiring run helter skelter like a Chinese fire drill in every direction with ten random splices per wire! It can be as nice or as unpleasant as YOU choose to make it!) SHIT DON'T WORK! If you have an electrical component that doesn't work...be it a bulb, a radio, a speaker, a wiper or what-have-you...don't panic! It can really only be one of a few things. First, the component could be defective or worn out. Disconnect it and check to see that you have power coming into the component or socket. If you have power, and the ground checks out good with a test light or a continuity tester, then the component is bad and needs to be replaced. If you have no power coming to the component, then you must trace the wiring back through the circuit to find out where the break is. It will likely be a fuse or a switch, or a faulty connection somewhere. With power coming into the component through the wire, hook a test light from the hot wire to the component to either the ground wire, or the surface where the component was grounded. If the light is on, then the ground is good, and the component is bad! OTHER ODDITIES I could go on all day listing other oddball instances and examples, but hopefully you're getting the idea. Wiring is not some black magic wizard's trade, it's a simple as current running through wires to a designated location. If current is not getting to that location, it is taking a short cut somewhere, and you need to put it back on the proper path! A word about tail or brake light bulbs. They often burn out the fillament, and the fillament can lay across the contacts inside the bulb and "backfeed", which will do odd things like keeping one arrow on your dash mounted turn signal indicators lit, or just blowing the fuse for that circut until you find the faulty bulb! Happens alot, actually! So many problems that drive people crazy when it comes to their electrical system can actually be easily diagnosed and repaired if you take a deep breath, clear your head, and think stupid sometimes! Don't make the problem more menacing or complicated than it actually is...odds are, it's something pretty damned stupid that's got you all in fits! You just gotta THINK stupid to find it!!!! Now, I know this post won't solve every electrical problem, far from it...but it should help to show you that these things are not spooky or impossible. With a little bit of experience, and application of the techniques I've outlined...you'll be thinking stupid and conquering electrical gremlins in No time...making you the hero amongst your buddies who freak out at the slightest electrical enigma!!!
Fat Hack; Good post, nothing scares the bejeezus out of rodders more than electrical snags. I'll save this, thanks.
FH, great practical tech. I agree that most all electrical problems turn out to be soemthing simple, but is often overlooked. You give good advice to break down the problem and think about what affects the different items in what way. So you can determine what the problem is and do effective problem solving, not parts replacing.
Outstanding coverage of the basics! I'll only add not to overlook loose or corroded ground connections - particularly on older cars & especially if running 6V system. [ QUOTE ] Another "field test" that my old off road buddies used to try was to touch a wrench or the tip of a NON magnetic screwdriver to the back center portion of their alternator. If there was a magnetic pull, the alternator was thought to be good. Hey, I don't know how much truth there is to THAT one, but many guys insist that it works as well as pulling the battery cable! [/ QUOTE ] This works well on alternators that have a separate voltage regulator. This test tells you that the alternator is getting the excitation voltage from the regulator. If there is no magnetic pull at the back of the alternator, it could be either the voltage regulator or the alternator. Again, excellent post!!
Thanks...great job on all the tech, FH. It's scary to think that all this good info is coming from someone who rides a girls bicycle....! Brian
One thing I forgot to mention involves a word of caution about car batteries. They give off explosive gasses, and playing around with them can be quite dangerous! (Ask me, I know!) When disconnecting cables, whether the vehicle is running (as in the field test I described) or not, always turn your head and look away as you pull the cable away from the post. One spark is all it takes to set that battery off like a BOMB! How do I know? When I was 18, I tried starting my motorcycle by running jumper cables from my running Chevelle's battery to the cables on the bike (no battery in the bike at all!). The bike fired right up, but something happened and the battery in the car exploded. Let me tell you, it sounded like a stick of dynamite, and the acid and shrapnel went EVERYWHERE! By some weird stroke of luck, I had my back to the car and was bent over messing with the choke on the bike. My jacket and jeans got an acid bath, and a few shards of plastic ripped through my coat, but did me no harm. Cleaning up that mess was quite the task, and within days, my jacket and jeans were disolved to nothing, and almost every wire and hose under the hood of the Chevelle had to be replaced! This story goes further, however...and takes a couple of interesting twists! Being that I had just blown up the battery in my car, I was in serious need of a NEW battery! The kid next door had been shaken out of bed by the explosion, and came over to see what was going on. He told me to take the old battery that one of his mom's boyfriends had left in their yard the year before. It was an AC Delco that had been sitting in the driveway next to the house for almost a full year. I dropped the battery in, and went to get the charger, expecting it to be dead. On a whim, the kid turned the key while I was in the garage and the car fired right up! Guess that puts to rest the age-old wive's tale about batteries going dead if left sitting on cement...or even outside! The other interesting twist was the exploded battery! It was an Accel Deltacell, and it had always been tough! I had run that very same battery in my old Pinto, and was able to drive the car half a block using the starter when it ran out of gas! Anyway, the exploded remnants of the Accel battery were sitting by my garage a few days later...litterally nothing more than two bent posts sticking up out of a shattered base that was maybe an inch in height at best. For fun, I hooked the jumper cables back up to the bike, and the "ghost battery" fired it right up! Amazing! But...back to the moral of the story...always shield your face when connecting or disconnecting any battery (or hooking and unhooking jumper cables)...you don't want the last thing you ever see to be pieces of your battery and a wall of acid coming at you! Think STUPID...but Work SMART!!!
Just to keep all this electrical tech in one post for easy future reference, I'll add some more tips and tricks I've gathered over the years with y'all here! FORD STARTERS The starters found on typical Ford V8 engines from the 60s on up into the 80s are among the simplest devices you will ever encounter. I'm talking about the type with no solenoid attatched to them...the ones that use the familiar fender-mounted relay. In my supemely low-dollar days, I discovered just how embarassingly EASY these starters are to service! Being so simple in design, the only thing short of physical damage (bent or siezed shaft, broken nose caone, etc) that ever stops them are dirty, pitted or grooved brushes and armature contact surfaces! If your starter looks to be free from damage, and the drive gear is in good shape, then you can save yourself the cost of a rebuilt starter by fixing it yourself. The process is so simple that it can be done sitting on a curb with a few basic tools if need be! With the starter removed from the engine, taking it apart is easy stuff. Remove the small inspection cover, then the two long, skinny bolts that hold the starter together. Inspect the brushes...if your starter cranked slowly or not at all, odds are that the concave contact surface of the brushes will be grooved, pitted, dirty or all of the above. I simply use my finger wrapped with emery cloth to "sand" the gooves out and bring the contact area back to a smooth, shiney clean finish. Be carefull to keep the half-round shape, though...do not sand 'em flat! Switching to a finer krokus cloth, I add a nice polish to the contact areas on the brushes and on the armature as well. At that point, I wipe off any sanding dust with a clean rag, and re-assemble the starter. Pop it back in and you're good to go! I've done this on my own Ford vehicles and several for others MANY times, and it's always worked out fine! Believe me...when you shell out your bucks for a "rebuilt" starter, you're lucky if you're getting one fixed THAT well in some cases! If I painted 'em, my fix-ups would look every bit as good as most "rebuilt" starters!!! What the heck...it's worth a TRY, ain't it? It can save you $30-$40 bucks and also the trouble of running back and forth to the parts joint to find a rebuilt that WORKS! (Another tip that old time four wheel and off road types will know well!) Alot of times, in the process of removing your starter, you may discover a bad switch-to-starter cable coming from your relay, and the end that connects to the starter may be badly corroded. In many cases, THAT will be your REAL problem! Always clean the cable end real good, or replace the cable. Once more, a thin coat of No-Oxide will keep that connection good for a long time! Another note, some Ford starters have the cable attatched to a threaded stud that comes out of the starter body, and others attatch the cable to a folded tab of metal with a threaded hole in it using a bolt. They can be interchanged, but the ones with the stud mount are usually labeled as "heavy duty" by most parts guys or backyard mechanics. I've used both on the same vehicle and noticed no difference. As long as the connection is clean and the brushes are in good shape, she'll crank!
The Jalopy Journal
