I dont think they do, but if they do i have never noticed it

 

Have seen it on other makes never HUMMER.Maybe you have a loose belt or something.Do you have skweekage?????

 

sounds wierd like the car has a weak battery

 

Thanks gmpartsdude

Apparentlythe Alternator and or Batteryare underrated to handle the electrical load designed into the vehicle according to the accessory list during normal operation. Also it seems to indicate the voltage regulatation of the charging cycle below 700 rpm is inadequate. How dumb was that or actually how cheap can you get, minimalists. No wonder we see all these Battery problems because the Battery is being cycled more often within a small voltage range. So this cycle is on and off more frequently causing spikes there buckling the plates, causing dead cells and a myriad of electricl faults.

AND YOU ALL THOUGHTI WAS CRAZY [sm=headbang.gif]

 

I have a 2008 H2 SUT and have the same problem from day one. When I press the brakes, my headlights and intruments dim for a second or too. I plan on taking it to the dealer.

 

The dealer replace my battery and the problem is gone, they claims it had a bad cell.

 

I have a 2002 GMC 2500HD with the 8.1 Vortec. Mine started doing the same thing at about 50k miles. What some have said about GM under powering these vehicles (alternator wise) is true. It seems to be even more noticeable in cold weather. A trip to the parts store for a reputable replacement (@ 130 amps) cured all my issues. It would seem GM only put a 100 amp in the factory models.

Also, capacitors weaken over a period of time (charging and discharging). They tend to slowly lose their ability to hold and discharge electrical current efficiently, which is vital when regulating voltage (and turning AC current from the alternator to DC which powers the electrical and charges the battery). When the regulator becomes weak, you'll start to notice a flutter in the interior lights (fast fluctuation in voltage from dim to bright).

Since the regulator and sensing circuit is a part of the GM alternator, it's best to replace the entire unit. If you have a lot of accessories, get the highest rated alternator you can find. You can't overkill, but you sure can under cut (like GM did)!

Also, as mentioned, you CANNOT tell a bad battery by it's voltage output!! It must have a load applied to it! Electricity (DC or AC) has two distinct components. Voltage and Amperage. It is TOTALLY possible to have one without the other! Think of voltage as the electrical pressure, and amperage as the content. You can have 13 volts with very little amperage, just as you can have water in a line with very little pressure. The voltage is the electrical potential, where as the amperage is the actual electrical content.

Hope this helps!