Question about 1993 GMC Sierra

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Truck has no electrical current (power) throughout truck. Has not run in several months. Battery still good. Alternator and ignition switch replaced.

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Sounds like its not grounded properly. Make sure your battery is grounded to the frame and the engine block. This way the assorted accessories and whatnot, that has (Pos.) power via wire connection, that is mounted to the frame or block, will successfully complete the circuit.

Posted on Nov 05, 2010

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if the bridge (three diode that turn AC current to DC in alternator) is bad it causes internal draw

Jun 19, 2014 | Chevrolet Blazer Cars & Trucks

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We have a second hand 2005 volvo S40. I have had alternator and battery changed in the past month an i'm having a issue with the wire that runs from the alternator to starter, it seem to be getting really...

Seems to me like a voltage meter would be a good place to start, to see just how much current is running through that wire. Check it in several key positions--off, on, starting, running. That should tell you a lot. It could be that power is being supplied at a time when it is not required. In which case, your ignition switch might be involved in the issue. Or a poor contact is making the wire act like an element instead of a conductor.

Oct 13, 2013 | Volvo S40 Cars & Trucks

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Truck keeps dieing

I will throw out a few ideas, maybe someone else had the identical problem and solved it. With the gauges spiking, you have electricity running around trying to find a place to ground. This is not the whole problem though, because something is staying connected long enough to drain your battery.
There are several Alternator tests, Voltage output, and the Diode tests. You can get good readings on Voltage and still have bad diodes. Diodes act like little gates to keep electric flowing in one direction. When these little gates fail, it allows the battery to discharge through the Alternator.
Your problem sounds also like a stuck Relay. Relays work differently than many people imagine. Relays not only connect the HOT positive wires, but also connect one Negative wire to another Negative wire. When the contact points inside the Relay stick, a Negative wire may stay connected when the vehicle is turned off. Same thing for Positive wires in the Relay.
"Not starting" when shut off is confusing. Do you mean it cranks normally and does not fire up? or do you mean the Battery is dead and the starter will not crank the engine? If the Battery is too low to crank the engine immediately after driving, then the Alternator is not charging while you are driving and is not showing a discharge.
You may simply have a bad Ignition switch. The Alternator needs power from the ignition switch and it gets into the Alternator through the small plastic clip that goes into the Alternator case. Shorting inside the Ignition switch can also affect the Relays powered through the switch. The Ignition switch would be a good place to start to make sure all circuits are getting reliable power and that when the key is out, power is really off.
So have Autozone, Advance, or Oreilys do a Diode test on the Alternator on the truck. Its free and doing it on the truck can reveal truck wiring problems that will not show up on a bench check.
Hope this helps.

May 28, 2013 | Chevrolet C1500 Cars & Trucks

1 Answer

What's draining my battery?

1: Faulty Battery: inspect and fill it with distilled water, if needed: battery may be shorted out

2: Alternator: the voltage regulator inside alternator will drain battery when it quits working: break unit open, and replace the regulator: or replace the entire unit with a rebuilt alternator.

3: Loose alternator belt, which slips and does not allow for enough revolutions to fully charge the battery - especially at night-time, when you are running your headlights and such.

Now, to do a test, which will tell you if the alternator has failed, in 10 minutes:

1) Simply loosen, but Do Not Remove, the battery post clamps / cables, from battery.

2) Start Engine.

3) With engine running, REMOVE both cables from battery posts (engine should continue to run) (if it does not / dies out upon removal of cables, then test no further): ensure to secure the positive post cable - wrap it with a rag, or set it on cardboard or rubber, so it does not ground: then reach inside, and turn ON your headlights: upon doing so, and highlights are ignited, if the engine dies out - if the engine quits running the instant you turn your lights on, with the battery cable disconnected off - that means that the alternator is Not Charging; that it is not producing enough current to run itself / maintain itself running / maintain the engine running; so it does not produce enough electricity to keep your battery fully charged - and, is in fact, draining your battery of any available current which was stored in it.

So, more likely then not, it's the electronic regulator / diode stored inside of the large alternator unit: but, because, your car is a 1990, the brushes on your alternator are shot anyway; so you are better off just replacing the whole unit and belt: and battery if need be.

I hope this helps somewhat: where, with ENGINE RUNNING at normal / higher idle speed, and BATTERY DISCONNECTED, and ACCESSORIES RUNNING, especially headlights and heater - the Engine Must Remain ON / Running - on solely alternator power.

In that: the battery is only required to start the car; stored energy / current for the purpose of starting the car, as supplied by the alternator - and adjusted by the regulator: a faulty regulator will fry your battery, by over-charging / allowing too much electricity to flow.

Good Luck,


Sep 18, 2011 | 1990 Lincoln Town Car

1 Answer

Truck was parked for a year. Battery, alternator, and Idle control valve have all been replaced. Truck will start, but the battery will not hold a charge, the dash gauges die and the truck shuts off. ...

With the truck running, use a multi-meter to check the + and - on the battery for around 14.2-14.6 volts. If the voltage is lower than this, there is a fault in the charging circuit. Check the Alternator Fuse to see if it is blown, trace the wires to the alternator and check for damage to the wires. If all looks good, you may have gotten a bad alternator. An ignition switch failure can also prevent the alternator from charging, but since your vehicle runs your ignition switch is probably fine.

Mar 10, 2011 | Dodge Dakota Cars & Trucks

1 Answer

I have a 2000 f 250 superduty I replaced battery and alternator but its still not charging

Check out your main wiring harness from the Alternators' heavy wiring. Some models had a green fuse a foot or two from the Alternator. It may be in a rubber cap like a Marine fitting and it may be blown.

If no success, the electric system is finicky. Although your battery may be new, a fully charged battery is putting out about 13.2 to 13.4 Volts. The Antitheft lockout will interfere with the charging and sometimes the cranking systems.

I have worked on trucks like yours and you need to fully charge the battery before connecting it to your truck. I have jump started similar trucks and they will charge with a jump attached, then stop charging several minutes after the jumper is off. You really need to watch the Volt gauge the first 30-40 miles after replacing the Battery to verify charging.

There is a remote chance that your Ignition switch is not providing current to the Alternator. The Alternator needs current going to the brushes inside. Check for power going to the Alternators plugin on the Alternators' casing with the Ignition switch ON. If it is dead, change the Ignition switch

Thanks for Using Fixya.

Jan 14, 2011 | 2000 Ford F250 Super Duty Crew Cabs

1 Answer

Car will not turn over. Dome light is flashing and a hissing noise coming from the dashboard.

You may have to replace your starter. The hissing sound that you are hearing my be the current coming from a faulty starter. Note: Replacing a starter, alternator, or battery can create massive electrical current that short out several electrical systems, it is good to have alternator and battery checked to make sure they are still strong before replacing the starter. Good luck.

Sep 19, 2010 | 2003 Chevrolet Monte Carlo

2 Answers

My car battery was dead when went to start. I jumped it them went to town in other car and came back and would not start again. Lights come on but will not turn over does not sound like it is trying to...

HI. It is possible that the battery has reached its life span, and may need to be replaced. If this is a new battery, the charging system may be malfunctioning. Use the procedure below to inspect the entire charging assembly for faults.

Wear protective eye wear and clothing and remove all jewelry when checking your battery and charging system. Jewelry is a good conductor of electricity and is not recommended. Most batteries wear out every 3 to 5 years and need to be replaced. Always replace your battery with an equal replacement battery to assure proper operation. Automotive batteries have a +positive terminal (red), - negative terminal (black). Electricity is stored in the battery and then supplied to the vehicle when the engine is not running. While the engine is running the vehicles alternator charges the battery for future use. (Note: never disconnect the battery while the engine is running. If the battery cable is disconnected from the battery a spark can be generated which can cause the battery to explode or a major electrical malfunction to occur.)

To check a battery surface voltage, remove the positive terminal protective cover. Connect the +positive side meter lead (red) to the positive side battery terminal. Connect the - negative (black) side meter lead to the negative battery terminal. With the vehicle not running and the car sitting over night the battery voltage should be between 12.5 and 12.8 volts.(You will need to use a voltmeter for this testing procedure)

The alternator is rotated by a drive belt driven by the vehicles engine while it is running. Electrical voltage and amperage are generated to recharge the battery and supply voltage to the electrical system of the car. The alternator is held in place with mounting bolts. There is a main electrical wire on the rear of the alternator that supplies voltage to a main voltage junction box. If your alternator is not charging properly, your battery will slowly drain down from operating all the electrical systems in your car and stop the car from running.(most non charge states will be the cause of a loose belt or a low tension rate, due to a mis-adjusted alternator. make sure you have enough tension in the belt for full rotation of the alt pulley)

Next, you will need to check the alternators output with the Amp meter.

Testing the amperage output of the alternator is good for measuring the amount (not the level) of voltage the alternator can produce. This test can be tricky because if the alternator is weak it can still show it as producing amperage. Which is good, but if the voltage is low, it will still allow the battery to go dead. To check the amperage output of an alternator an amp meter is needed. Once the meter is connected start the engine. Next turn on all electrical accessories and raise the engine idle to about 1200 RPM. The alternator should output the max amperage it was designed to produce. Example: a 90 amp alternator should output about 88 amps. Note: An alternator cannot sustain maximum output for long periods of time. If the alternator is forced to operate at maximum output it will overheat and fail. An alternator is designed to operate at max amperage output only for a reasonable amount of time.

((Connect the voltage meter lead the same way you would in a battery static voltage check, Start engine (do not drive) at engine idle the voltage should be between 13.6 to 14.3 volts. If not the alternator may need replacing.)))

Now, if the charging system is ok, move on to the starter, and ignition switch. Use this procedure to inspect these additional areas.

Step 1
Check for 12 volts on the large wire attached to the top terminal on the starter relay. It should have battery voltage. If not, the battery, terminals or wire is bad.

Step 2
Check the small wire on the solenoid for power when the key is in the start position. Remove the small wire on the solenoid and have a helper hold the key in the start position. Check the wire for battery voltage. If there is voltage, the starter is bad. If there is no voltage, replace the wire.

Step 3
Check the fuse in the fuse box under the hood on the left fender well. If it is good, check the relay by pulling it out and checking for power at one terminal with the key off. If there is no power, the problem is in the fuse box between the fuse and the relay. If there is power, have the helper hold the key in the start position once again and check for power at another terminal from the ignition key. If there is power, the relay is bad. If there is no power, the starter circuit is suspect.

Step 4
Check to see if there is power to the neutral safety switch if there is no power at the relay. Use the voltmeter to check for power with the key in start. If there is power going in, check for power going out. If there is no power going in, the security system or ignition switch is suspect. If there is power going in and none coming out, the switch is bad. If there is power coming out, the problem is between the neutral switch and the relay.

Step 5
Remove the cover on the bottom of the steering column. Check the solid yellow wire for power when the key is in the start position. If there is no power, the ignition switch is bad.

Dec 11, 2009 | 2007 Hyundai Elantra Limited Sedan

1 Answer

87 f250 drained brand new battery

I would first have the alternator checked by an auto electrician to ensure it is working correctly and is providing the correct volume of current. It may be faulty and when driving you will be drawing battery power instead of power from the alternator to run the electrics. This will drain the battery.

Alternators do not last forever and if you are still running the original unit it is likely to be on it's last legs and you will need a replacement unit.

Nov 30, 2009 | 1987 Ford F 250

2 Answers

02 Chevy 1500 v6, started to lose power for a moment and then would be fine. After a day or two it lost all power - not electric but engine. Bought a code reader that shows no problems. replaced the...

When you say it has lost power, the engine is running but is bogging down or is it electrical because you replaced the battery and alternator, no headlights or gauges are not working.
Let me know.

May 09, 2009 | 2002 Chevrolet Silverado 1500

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