My 03 yukon xl is having a issue with entire electrical system check engine light dianostic shows low battery low charge when it reads,when operating front power windows all lights dims.scanner shows good batery voltage.

sounds like fuelpump check valve or regulator not holding residual pressure you need to check if fuel pressure is holding with engine off approx. 40 psi

It sounds like you have a bad connection on the battery. Make sure to clean the connections, make sure they are tight, and make sure the ground cable has a good connection at both ends, battery side and body/frame side. The bad connection is the only answer when the battery is fully charged and you turn the key and it all goes out. If you can turn on your headlights and press the brake at the same time, and they work, then it may be something else, but I would be amazed if they do work given your description of your problem.

So, make sure the battery is charged and clean and tighten all your connections. Test battery connection by putting it under a load with all the lights, head, and brake at the same time. If it goes off then, redo cables again.

Good luck.

I had the same problem in my Yukon Denali And after 4 throttle body's, replacing gas pedal, rewiring the grounds replacing sensors, took it to not one but two GMC dealerships who were useless they can't fix their own trucks they're not the brightest !!!! After thousands of dollars I found a mechanic very familiar with this issue you want the solution it will cost ya 500$ for me to tell ya!! Just kidding I know how frustrating this problem is okay here is the fix the problem is these electric throttle bodies are GARBAGE!!!!!!! Don't matter what u do or what u replace it will come back on unless u convert your electric throttle body to the old cable throttle the actual fix was 900$ but I spent thousands and thousands trying to fix it!!! Please save your money and tell ur mechanic u want to convert to the old cable throttle!!! Gmc is well aware of the problem but won't fix it for u cuz they're useless

Hi, There is a slim possibility that the new (or rebuilt) battery is defective.
Here are the things that cause it. And the things that don't.

The voltage regulator controls how much electricity is used to charge the battery and how much is going into the electrical system of the car. The electrical system may has been designed to integrate the voltage regulator into the case of the alternator. If that is the issue, the alternator can be replaced, or if there is a skilled person that does rebuilds in your area, he will know how to change the diodes in the voltage regulating section of the alternator. You can save money this way. If you have a volt meter or a multimeter, (commonly around $25.00 these days and between $4 and $7 at Harbor Freight), you should get a reading of around 12 volts from the battery when it is charged and the engine is off. If the battery is down, the voltage should still be in that area, but not enough of a kick behind it to do anything but light a small bulb. When the car is started and the voltage regulator is doing it's job you should get at least 13.5 volts DC at the battery terminals.

Many of the symptoms that occur also happen because of poor electrical contact at the battery.
Use Baking soda and water to clean the terminals of the battery of corrosion. And then use a battery cleaning tool for the battery posts and the battery wire clamps that go around the post. Make sure all of the connectors and wiring is sound.

I would then test all of this doing the following steps..

Charge up the battery.

Then connect the system and do the voltage checks. If the Battery is charging properly, the regulator will gradually reduce the charging voltage it is using to charge.

After 15 minutes, shut the engine down and check the battery voltage. and turn on the headlights to see if they are still bright.

If the voltage is at 12 volts DC the battery is OK.

One very simple test of a charging system is to charge the battery, start the engine, then pull the positive terminal off of the battery. If the engine dies, then the voltage being generated from the alternator is too weak.

If your battery is bad it will show low voltage. If one of the plates in it is shorted out. The voltage will be 10 Volts.

Hope all of this helps,
Happy New Year,
Mark

There seems to be a no charge state in this case. I recommend checking the battery first, then, move on to 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). 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). 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). If the voltage is not up to specs, replace the battery asap. If the battery is ok and showing good voltage readings; Move on to the alternator/generator drive belt and amperage test.

The alternator is rotated by a drive belt, which is, driven by the vehicles engine crank shaft pulley 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 alternator pulley.

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

Testing the amperage output of an 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(False reading); 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 will be required. Once the meter is connected start the engine. Next; Turn on all electrical accessories and raise the engine idle to about 1300 RPM. The alternator should produce the max amperage it was designed to produce. Example: a 90 amp alternator should produce about 88 amps. 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(due to a failed regulator). An alternator is designed to operate at max amperage output only for a reasonable amount of time. Once you have verified the amp readings, check the voltage. To check the voltage, 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.

• NOTE_ Be sure to inspect the battery terminals for connectivity issues such as corrosion and so fourth..

That is correct! Your alternator isnt putting out the necessary voltage/amperage to keep the battery light off.

Have the vehicles charging system checked at a local parts store. They can also do a free load test on the battery. Just to be sure.

I recently had a low engine power on my 2003 Denali. The check engine light came on and I couldn't go above 40 mph. I took it in the next morning but by this time the check engine light had gone off. The mechanic had just recently seen the same problem in another Denali in which they changed the battery and had no problems since. I also decided to have them change out my battery and I have not had the problem since either. I would stay away from the dealership if I were you, and always get a second opinion. Most smaller shops wont charge for a diagnostic where the dealership will charge at least 80 just to tell you what might be wrong and that will only work if you have a warning light on at the time.

We had the same issue with our 2007 Yukon Denali XL. Died on us twice after sitting for short periods of time; once we watched a DVD with the engine off and battery died within 10 minutes. The dealership kept it overnight to troubleshoot why the battery died so quickly. They said the radio was "pulling" too much from the battery. (They supposably fixed it) But again a few days later the battery died again after sitting overnight. We brought it back to the dealership and they brought in a GMC "expert" to replace the entire DVD/CD/Navigation system. They also replaced our battery with a much larger battery, similar to the ones that GMC puts in there diesel trucks. They had our Denali for 5 days, but it appears to be fixed now.
Getting it fixed correctly wasn't without headaches, but it was all covered under warranty, including the battery. And they are updating the nav w/ the new edition disc as well for no charge.

I had the same problem with my 2003 denali and came to find out that it was the battery causing the problem. the battery with sufficient power will dictate the tps. if the battery is low or bad, it won't have enough juice to allow the tps to. work. get your battery checked.