trouble code 75?
 

anyone ever had this code? the book says low ignition feed voltage, my truck is running like it has a dead cylinder. BTW its a 93 k2500 5.7 4l60e truck.

Re: trouble code 75?
 

Let's help out a brother.....

Re: trouble code 75?
 

Code 75 = System voltage low

Test the voltage with a good meter.

If the voltage is low, that can cause computer to try to compensate with its adjustments and can cause weak ignition.

Re: trouble code 75?
 

Now, you gotta figure out why the voltage is low and fix it. Is it a bad accessory drive belt (stretched, for instance)? Does the belt slip? What is the voltmeter on your dash showing? Is it less than 13.5V? Just because it may show 12V, doesn't mean all is well. Have you had your alternator tested at a parts house (AutoZone, O'Reilly's, Advance, for instance)? There was another poster here who ended up replacing his alternator, even though the parts house tester said it was good, even upon multiple testings. What about your battery cables? Are they corroded? The positive post has two cables that have a longer bolt to hold them on. Corrosion can build up within the cable housing at the battery end and that will reduce the voltage within the system. Finally, the battery: Is the top of it wet? Does it look like it has been damp? Is there corrosion evident at the base of the battery in the tray?
The heat and the charging process can cause the electrolyte to "boil" out of the battery and that is what makes the battery fail and look wet.

Hot weather can sap the battery and cause it to fail from one start to the next attempt to start....been there and done that, three times. Only had one battery to fail in cold weather in almost 50 years of driving.