Question about Cars & Trucks
The alternator was over charging (17.5 volts) and cooked the battery (boiled it over). I replaced both with new and now the engine is hard to start and after it does start it idles fine for 4 or 5 minutes and then goes to fast idle and it won't release back to normal idle. I have not had the chance to check the sensors for their voltages and resistance but was told that when the alternator started over charging that it probably burnt up the computer (PCM)
Given the age of the truck, and the lack of diagnostic abilities of the computer Ford used in that year, I would get a used computer to eliminate it from the list of possible problems.
The computer could be "tested" but not without taking it apart to look for problems in the circuit board and components.
And yes it is very possible the bad alternator fried some diodes and drivers on the circuit board.
Posted on Jan 23, 2013
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Posted on Jan 02, 2017
Ok, i understand that you have replaced the alternator, but there seems to be a non charge state in this case. i recommend checking the charging system. use the procedure below to isolate this issue.
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). The battery in this illustration has a protective cover over the positive terminal to prevent short circuit in case of an accident. 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.)))
Posted on Sep 07, 2009
it is possibly the throttle position sensor(tps) malfunctioning. basically the computer or "brain" of the car thinks the throttle is in a different position than it really is and automatically makes adjustments to fuel, air ect.... based on these false readings from the sensor thus causing the engine to react a little different when you expect to have power.
Posted on May 14, 2011
Tips for a great answer:
This code indicates that a fault has been detected in the generator lamp control circuit. The PCM may have also detected an abnormal voltage reading from the vehicle battery, starting, or charging system.
In the event of generator lamp control circuit fault, a trouble code will be stored and a service engine soon lamp will be illuminated. Some models require multiple drive cycles (as many as 8) with a failure in order for the service engine soon lamp to be illuminated and others will activate it on the initial failure.
This code indicates that a fault has been detected in the charging system circuit. The PCM may have also detected an abnormal voltage reading from the vehicle battery, starting, or charging system.
The most common cause of this code can be traced to a faulty alternator. Other causes could include a bad battery or starter, open or shorted wiring or battery cables, insufficient battery primary or secondary grounds, defective voltage regulator, corroded battery terminal ends, a faulty PCM (rare), a large battery drain, or a defective battery.
Technicians report that batteries and starters are often replaced in error when the alternator is either not charging or overcharging. If the battery is discharged, charge it and test the vehicle charging system to make sure that it is operating properly.
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