Question: I have a new but cheap alternator. This is the negative circuit voltage loss. Used my multimeter to check the dc voltage while running and got 11.9v-12v. Question: I have an 03 Dakota. Ask an assistant to start the engine and hold engine speed at about 1500 RPM. I believe is the same model. Question: I have a 2014 Nissan Pathfinder. The next checkpoints will help you isolate the source of the noise. Answer: Make sure you have clean and tight connections to the voltage regulator. Now repeat the test, but this time, connect your meter leads between the battery negative post and the alternator case. Otherwise you can check the repair manual in your local library. Last year, the car didn’t want to start, so I replaced the battery. further down in this article. It seems to charge the battery, but then the battery light comes on. I have driven the car, and I haven't had any problems running the AC, lights or radio. This post can give you an idea about checking for voltage drop: Question. Make a Visual Inspection of the System. Answer: Check the belt. You find yourself adding water to the battery frequently. I can unplug the alternator, plug it back, and the light will go out. Answer: Have the battery check; this could be a worn belt and/or belt tensioner issue. What happens behind the scenes will shock you. In turn, the alternator needs to replenish the battery and provide the power for the vehicle loads through the charging cables and connections. Voltmeter (–) test lead to battery (–) post. Had battery checked twice. I am not sure what this means I'm assuming an under charge but I'm not sure. Dan Ferrell (author) on September 17, 2019: There could be a problem in the charging system. This year I installed a new battery. This other post may help here: If necessary, have the alternator checked (worn, bad voltage regulator) and battery. 1)  With the carbon pile tester still connected, connect the voltmeter to the negative  battery cable. They replaced the Alternator. Your reading should be at least 0.5 volts above base voltage for your system to keep up with electrical system demands. Calculating Total Circuit Voltage Drop 2. 3)  Read the voltmeter and record voltage. You should get around 0.4V or less of voltage drop. The battery voltage was 14.09, cranking 10.590. Use a belt wear indicator or check your maintenance schedule for the replacement interval suggested by your car manufacturer. Take a look at the grounds and the output wiring to the battery. After 20 seconds, the alternator quits charging. Hi Dan got a 2017 pathfinder battery light cane on car stop moving . I changed two alternators, but I still have the same problem. It is just running on the battery. A question, if a/c compressor pulley is not free spinning on its own but belt is sliding right past it as intended would that put strain on any other parts associated, with desired effect. if you cut the lights and radio and A/C in this situation the car gets the last amount of juice and rides good again enough to get to a safe place. It is good to pay attention to any changes in the gauges. 1)  Add positive circuit loss and negative circuit loss to get total system loss. I have a self exciting alt, 24v it only stays excitied when i have the warning lamp hooked up. My compressor belt is dragging when i switch the aircondition on. Do you have any idea what's going on? However, when I turn the a/c and bright lights on to put it under a greater load, voltage drops down to 12.0-12.3. Look for white residue under the cap (if module is located inside). What would cause my Cadillac's battery to heat up? You should get 0.5 to 2 volts higher than base voltage. I have not driven it yet. This is the positive circuit voltage loss. Most alternators use diodes inside a rectifier to turn Alternating Current (AC) into Direct Current (DC) for use by the system. The battery was excellent, but the alternator showed low charge. Question: I have a Toyota Corolla VVTI model 2004, I have changed the alternator but the battery indicator is still present. 1993 F250 4x4 7.5 gas engine. h) There could be an alternator wiring problem. Even so, the shaft bushings and … Have the battery checked to see if there was any damage. I have changed the alternator more than 8 times. If it does, the alternator needs new brushes. What should I have the mechanics do next? You can even do these measurements yourself with the manual. Dan Ferrell (author) on September 07, 2019: Probably the nut holding the stud to the rectifier is loose. It will help you identify wires, specific components, and possibly suggest some specific tests recommended by your manufacturer. Check the section "Troubleshooting for Unusual Charging System Voltage Drops" below to check for wiring problems that can lead to this condition. Answer: Have the battery and alternator checked. I found an aritcle that said to connect the black wire of my multimeter to the ground on the batter and positive check the 4 insertes of the plug that connects into the alternator. Copyright © 2021 BorgWarner Inc. All rights reserved. g) If you recently added an electrical accessory to the vehicle, you may have over passed your alternator's capacity. After replacing it and checking my work, the battery light with a warning "check charging system" comes on. It will work fine at times, then at other times the voltage steadily drops, especially if I turn the lights on. Touch the black meter lead to the alternator case (ground). MAY I ASK A QUESTION . Check the cable for damage, or a problem at the connectors. A typical alternator may last anywhere from 8 to 12 years. At home, with the transmission in Neutral or Park, increase engine speed to the same rpm and see if the light comes on. Question: I installed a new 105-amp alternator in my 1982 Chevrolet C10. Answer: If the negative cable gets too hot just cranking the engine, there's too much resistance in that part of the circuit. Often, it is possible to diagnose and solve the problem on your own using a few simple tests and tools. Tapping the alternator shake the brushes a bit and help them make better contact or the copper wires connected to the brushes are damaged. The key point here is to do the proper diagnostic as soon as possible because a bad alternator can ruin an otherwise good battery, and other components as well, depending on the fault. I have a 2012 kia sorento. 7). ", A voltage drop test will assess voltage losses at the battery, the alternator and the starter. One is to buy and keep it for years hoping that the price increases, the other is to buy for a low price and flip it for a quick profit. 2018 ford F-59. Light dim and radio and everything turns off as battery drains is that my alternatoe. This other post may help: Also, make sure to watch this other video: https://www.youtube.com/watch?v=OqylgRKiC-A. Then, check the voltage drop on the charging circuit: Then, have the alternator checked, if necessary. please help me. Still, the price was $400 for the part. Belt should have the proper pressure. Answer: Check the serpentine belt and the pulleys it runs on. A sudden change in the load can cause the voltage to fluctuate while the regulator is trying to stabilize it. Got the battery tested and recharged, replaced the alternator and the warning light went off and came back after a month. If your battery and alternator test good, check the charging circuit. This is an important figure due to the fact that OEM alternators are typically ill-equipped to handle additional loads from aftermarket equipment and upgrades. On early models the indicator light on the dashboard should come on when the ignition key is in the On position, otherwise, you'll have problems at idle. ensure the engine is running for best results. A worn belt may slip intermittently, affecting the charging system. If this happened right after installing the new battery, probably the negative cable is not well connected or is damaged or there's some corrosion. 1- Is it possible to cause a short if the battery is hooked up back with the alternator removed? If it is Okay, the circuit to the warning light is shorted. And check the circuit fuse for the radio. And I check the dc voltage while the car is running and I'm getting 12.8v. WHEN THE GENSET RUN WITHOUT LOAD THERE IS AN ALARM HIGH VOLTAGE BATTERY 30.2V . The output voltage of an alternator depends essentially upon the total flux in the air gap. 2)  Load the carbon pile tester to 500 amps and record voltage. Answer: Have your battery tested and also make sure all battery cables and their respective connections between the alternator and starter are tight and clean. There could be a bad connection or wire that is not too evident. Question: Can brake fluid ruin the coating of copper wires inside the alternator? Consult your vehicle repair manual, if necessary, to locate the alternator fuse or fusible link. Question: Why does my '99 Bonneville’s charging system go down to 12 volts only when in drive or while idling? Any help ? I have a 2001 Infiniti g20 and It starts but wont stay running and the battery is draining after I charged it at autozone. An RV is an expensive thing to buy, and once sold, it depreciates literally every month. Make sure the alternator is the problem. Because the voltage in a healthy ground circuit should be about zero, some technicians call it ground zero. New car? What could it be? My truck still will start but will shut off once batterie is dead. Are you taking the voltage directly off the battery itself or the cable clamps? It happened again yesterday. Start the engine and let it idle. Hope this helps. Once you've determined the condition of the system, you can go over the next section to zero in on the potential problem(s) that may be causing the condition of the charging system. What about trouble codes? They agreed alternator replaced the alternator and it is still doing the same thing do you have any idea what else could be wrong? What’s the cultiprit. Checking the circuit voltage drop will help. Question: I had my alternator rebuilt. And now, about 6 months later, the same thing is happening. crankshaft comes from the electrical load power drawn from the alternator. So far it does not seem to drain the battery. Less likely, but it could happen, a fault in the computer can prevent the alternator from charging the battery. Ground this wire and turn the ignition to On. I have a brand new alternator, PCM, and ACDelco battery. Also, check the belt and pulleys. It’s simply not there yet the alternator is not charging . "One volt drop generally equals a loss of 30 engine cranking rpms. This other post will give you an idea on how to go about the test: Question: I replaced the original alternator on my 2015 Kia Forte. Alternator problems and charging system problems can affect your vehicle in different ways. What do I do next? What can cause this problem? I would be concerned if output voltage exceeded 15v though. Check the voltage drop in the circuit. If the voltage drop exceeds specification, check for corrosion, frayed strands of wire, loose connections or a battery cable gauge that is too small. There's a special circuit for the battery indicator on the dashboard. a) Check the drive belt or serpentine belt, especially if you haven't replaced it in the last five years. If your vehicle is equipped with a heated windshield, don't turn it on; this can make alternator voltage go over 100 V. Since you'll be working around alternator connections, this could be dangerous. Add a temporary ground connection from the battery to the chassis. Answer: Check the connections. They should be clean and tight. If not, check the wires and connections between the battery and alternator. These alternators need the right pulley ratio and pulley diameter to work correctly. You may want to try a voltage drop test. The alternator is at the heart of the charging system of your vehicle. Go over section IV in the post. Why does the light come on and not go out? I have an aftermarket voltage regulator, and a high output 320 amp alternator and my battery dies if I don’t unhook the wire from my battery to the cars fuse box. – atraudes Feb 1 '17 at 0:35. How can I check the alternator? He checked it again, replaced the regulator and said it's putting out full voltage, but on the car, it's doing exactly as I mentioned before, no voltage at idle, full voltage when revving the engine. Answer: First, make sure the belt is properly installed, not slipping, and accessory pulleys are running OK. If there are charging system issues, also check that the wire and connections going to the starter are all good. When one or more diodes go bad, AC can leak into the electrical system. The battery,alternator and belts are new. At no load, this flux is established and determined exclusively by the dc field excitation. Question: On my way home, the alternator light came on but made it home fine. Hope this helps. Problems only happen once things warm up a little. Occasionally cylinder 7 and 8 are too lean. I replaced the alternator because it was causing a camshaft position sensor code. Thank you for sharing your opinion and experience. Answer: This is usually caused by a faulty diode(s), making alternator work extra-hard. Is there a way to tighten it do I take alternator apart and replace the Standard Ignition Alternator Terminal? Answer: If your battery is good, the alternator rate of charge will drop after recharging the battery upon firing up the engine. I replaced both. 2)  If the voltage is greater than 12.6 volts (AGM batteries 12.8 volts), surface charge must be removed. I just replace my ecu because its faulty. I would love other people's two cents on these. Dan Ferrell (author) on February 25, 2020: Have the battery tested at your local auto parts store. You'd be surprised what you find out. Now I am confused. Identifying the type of noise and when it happens can help you diagnose your transmission problem. When my truck's air conditioning or heater is on, the voltage drops below or at 12v and makes a load squeal sound. You should get around 13.5 or so. Can you give me any pointers? Answer: The problem might be with the battery, starting system, ignition or fuel system. Some models, like GM, have a fusible link in the circuit. If everything seems okay, have your battery tested. Otherwise, the charging system can't meet the demand and charge your battery. Alternator quality can be another factor of course. What else could it be? The Bullnose Mercedes is a real truck. Here's a test you can do: Use a length of vacuum hose to listen for alternator noises. You might get occasionally over 16V from the alternator. If you suspect a problem with the charging system, have the battery tested first. Also, you may want to check the charging circuit. The battery light would come on at idle, and then when I reached approximately 2000 rpm, it would go off. Question: On my 2003 GT Mustang, when accelerating, my battery light flashes 3 times. Think of your starting and charging cables as a two-way street. 1. Two reliable mechanics can’t figure it out. Question: Can the dash charging gauge on a '67 Pontiac Catalina cause the charging system not to work? flicker on and off intermittently during acceleration and deceleration. Also if your reading volts from your efi system the alternator might be ok, but heaps of voltage drop in the wiring and connectors. This other post may help: I have a 1999 jeep cheakee and the alteenate has been tasted and is good but. Can you give me some pointers, please? e) There's a parasitic battery drain stealing power from your battery. It comes on for a few seconds then turns off for a while. If the alternator or charging system was faulty, it could've damaged the battery. Belt, cleaned batt.post,cables and all wires on fender mounted starter solenoid. Dan Ferrell (author) on September 09, 2019: There could be a loose wire in the circuit. Now I am having a problem getting it to charge at idle, I get 14.5 volts at 1500 rpm, but as soon as I release the throttle it drops down to battery voltage, I've returned the alternator once already. What is going on? Check your meter display. Powerful, noisy, smelly, rattly. Occasionally, a BATTERY SYSTEM FAILURE light will come on. These other posts may help: I have a GMC truck my daughter left two of the interior lights on when she got out eventually I think they automatically shut off when I went to start it that morning Deb interior lights come on to show they were left on it started right up I only live maybe four blocks from work went to work shut it off came home at lunch went back then she took it to work a lot farther a couple miles or so down the road she got gas shut it off when she went to start it it kind of did the click click click the click a friend charge the battery the keep has been popping off but when she drove it it was like start acting like it wanted to die and the lights went down but I don't know I get I wasn't with her so I'm not sure would that be that battery or could that be the alternator. Thought it was fixed but now the battery is dead and won’t recharge. The next day, the truck was hard to crank and would only stay running if my foot remained on the gas. This other post may help: o have a 2000 chevy silverado 4.3 i put new alternator and battery and relays but yet its still dragging where dose the one wire go to from the alternator and why dose it keep dragging. The belt is good, connections are good. Connect the carbon pile tester positive lead to the B+ stud on the starter solenoid. Make sure the belt has the proper tension. So consider your options. 2)  Connect the voltmeter (set on low scale) to look for excessive resistance on the (+) side. Have your battery checked at a local auto parts store. 3. Engine Cranks Slowly, Doesn't Crank or Stalls. Under load, however, the air gap flux is determined by the ampere-turns of the rotor and the ampere-turns of the stator. I ran new wires to the PCM and fuse box for the connector. Sometimes you can notice this when the headlights, instrument panel lights, and other interior lights dim during engine operation. (Your battery should have a minimum of 12.4 volts.) It's not uncommon for an alternator or starter to be replaced because it’s believed to be faulty or run its normal life cycle... only to later discover that the root cause of the problem doesn’t reside with the alternator or starter. Like I said been on 2 years along with abs light. Volts so it was working good. Question: So I have a 1998 Honda Accord, and it burned out the alternator and battery at the same time. I'd start by checking the alternator and battery fist. Question: I have a 2001 Toyota Solar, and the alternator keeps wearing out. Of course, you want to make sure you got the right alternator for your application. Troubleshooting for Unusual Charging System Voltage Drops." If a single phase of a three-phase alternator is heavily loaded, its voltage will be reduced due to the IR and IXL drops in the stator winding. Question: I got a 2012 Nissan Xterra. It is a good idea to have on hand the vehicle repair manual (or a good aftermarket manual) for your particular car make and model. They may have the manual in the reference section. Best of all, it is bullnosed, with a big ugly vertical exhaust stack. This is the negative circuit voltage loss. A year later, I noticed the lights started to dim, then to fade back up. For the sake of argument, presuming there is no parallel causes. If not, the circuit for the warning light might be the issue. I have replaced the alternator twice, and replaced the battery with a good one out of my own WRX. With no accessories on, the car makes a healthy 14.0-14.4 volts. Troubleshoot for unusual voltage drop. Answer: The problem could be in the circuit. everything came back with the normal .2 .3 ohms reading. If it's loose, it won't charge properly during hard accelerations. Turn on all electrical accessories like A/C, blower motor, headlights, defroster, wipers. 1)  Ensure the battery is charged to 12.4 volts minimum (AGM batteries 12.6 volts). I have also noticed the positive battery post on my battery gets hot. If there's too much resistance in the circuit, it'll wear out your alternator. Recently, the ABS light went on, then, after a few minutes the regular red brake light lit and the car stopped. This convenient troubleshooting guide will help you find out what you need to know, using a few simple checks you can do at home using a test light or digital multimeter (DMM) and possibly a few other common tools. Question: I have a ‘03 Chevy Silverado alternator that whines and displays a check engine code, mainly knock sensor. Question: I have a 2006 Ford Freestyle. On some newer models using the incorrect battery can affect the alternator, especially those that interact with the ECU. Usually when alternators failed prematurely is because of a bad battery (electrical), voltage regulator issues, high electric loads (e.g. Voltmeter (+) test lead to starter ground stud or case. It means that the alternator voltage output is below 12 volts, or over its limit or has stopped charging the battery and your car is running on battery power. Whenever the load on the alternator is varied, the terminal voltage will also vary. If you don't have a scanner get a free scan from your local auto parts store. These other posts may help: Have 06 scion tc replaced alternator with a 05 that was in junkyard said they tesed it but battier still does not charge. Maybe there's an issue with the circuit or you may be expecting a charge at a low RPM threshold. Hope this helps. You can make some repairs using a few common tools. It starts up good and idles good now as well, but when I give it full throttle and get close to 3,000 RPMs, my battery light and park brake lights comes on and flashes at me. Question: I have a 1966 Ford Mustang and have swapped out the alternator 3 times. Do you know where I can find a visual of where all the grounds are on this truck? Question: I have a 2004 Ford F150. Touch the red meter lead to the alternator battery terminal B+. This fault could point to a faulty alternator or voltage regulator. Do This If the Indicator Light Stays On, or Goes On and Off. the other day, I suddenly lost power steering, the dash light came on, followed by the ABS light and the handbrake. Thank you! i) Have the alternator and battery checked. This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional. Changed alternator, changed battery, still voltage drops. Make sure that it’s good. d) Check your battery yourself, or take it to your local auto parts store. Put meter on it while running and watched min/max for about 45 min. Before you blame your battery, or the alternator, here are some preliminary checks you may want to do. ... but under load will drop voltage. 5a. Hope it helps. 5. It's possible the vehicle's diagnostic system is causing the light to come on after replacing the battery and/or alternator. The next three tests are best done using a load tester, but you still can use your digital voltmeter. Check your battery and see the "Alternator AC Voltage Leak Check" subsection further down in this article. Photo courtesy of Pentti Immonen on Wikimedia. The output of an alternator is usually expressed in amperes, which is essentially just the amount of current that the unit is capable of providing to all of the equipment that’s hooked into the electrical system. The battery is also brand new. 3)  Turn on and adjust the carbon pile to alternator-rated amperage output. Usually the problem here is the voltage regulator. You can try taking it apart and tighten the bolt. Make sure it’s still in good operating condition. Usually, the first sign that your charging system is in trouble is a "battery," "ALT," or "CHARGE" warning light illuminating on your instrument panel while driving. Many of these stores will test your battery for free. Question: I have a 2012 Town and Country with 110k miles. This other post may help: Question: What would cause my alternator to be charging where it supposed to be, then cause it to drop all of the sudden? There could be a number of things that triggered the ABS light - problems with the tone ring, wheel bearing, speed sensor (and wiring). Answer: Probably you are dealing with an alternator with worn brushes. Got a new battery and have the same problem with battery drain. One of the best ways to check the output of the alternator is to conduct a load test. 1)  Add positive circuit loss and negative circuit loss to get total system loss. Starter Circuit Voltage Drop Test (–) Side As you drive the car, you can monitor the voltage to see if the alternator is putting out over 13v at all rpm's. This voltage will be maintained when the battery is fully charged and the electrical load is low. the truck doesnt die. There could be a problem with the voltage regulator. Dan Ferrell (author) on September 21, 2018: Put new battery and altinator on 2001 f150 and its still over chargeing is it the pcm? There could also be a problem in the charging circuit, a loose, corroded or damaged wire can also prevent full voltage at low rpm. Often, engine grounds or loose wires or connections in the circuit can cause this problem. On startup, I have 14 volts at the battery. You'll prevent a faulty component from ruining other parts in the system, which would make your repair more expensive. Question: I have a Nissan Wingroad and I had to replace the battery before 18 months of use as it wouldn't start without jump starting. I dont want to drive my car until i figure it out. This post will give you an idea about how to go about it. Answer: Check all the grounds -- battery to body and body to engine. After a while, the warning lights went off by its self, power steering was restored. Answer: There could be too much resistance on that side of the circuit. Also check the connecitons to the alternator and wires. Also check that it has the right size battery cables hook to the battery. Measure battery voltage across the battery posts with your DMM. Dan Ferrell writes about do-it-yourself car maintenance and repair. The alternator went bad, and I replaced it along with the battery. Ive already double checked my work. Installed a voltemeter to read battery output and is always 12.4-12.6 off and 13.6-14.1 on. I know on a Harley it damages the voltage regulator if it comes unplugged while it’s running but if you unplug it before you start it it doesn’t hurt to run it other than the battery will go dead. I don’t want to pay another $ 600 to replace the alternator. We don't know what it is and have begun looking at the grounding cables and still flying blind trying to solve the issue. I have a problem with the alternator for COLORADA DMAX, I cannot seem to start the vehicle, we only start the vehicle once we charge the battery.Hoever this does not last, we can only start the veichle once the battery is charged.Please help? I changed my alternator in July 2018. Question: Our engine will take too much time to start. You have already charged your battery a couple of times and you just found out the battery is undercharged again. The voltage should hold fairly steady on a good battery while the lights are on but would 0.01V drop every 1-2s on a weak battery. What is the correct position, is there a charging problem or not? Voltmeter (–) test lead to the alternator ground stud or case. A basic knowledge on the electronic fuel injection system eliminates the guesswork in the calibration of LPG-powered cars. Voltmeter (-) test lead to starter B+ post. PLEASE HELP? If you notice the headlights, instrument panel, or interior lights dimming or flickering, power windows running slow, radio or gauges don't operate as they should, either your battery has a low charge, or there's one or more faulty diodes inside the alternator. The problem with newer belts is they look good even if they are worn. Dan Ferrell (author) on October 03, 2019: it seems the probelm is either in the charging circuit or the engine grounds. Can it kill the alternator if the connector comes out while the engine is running? Watch the engine rpm when the battery light comes on. Voltage drops on the positive side of the charging circuit can cause undercharging. Answer: You need to download the trouble codes. I’ve changed the battery and the alternator. (after replacing the alternator the battery light has been consistently on even with the change of the other parts. If the connector is OK, make sure you have the correct alternator for your particular model. Answer: Check the system specifications in your vehicle repair manual.