gmrulz4u Posted October 13, 2002 Report Share Posted October 13, 2002 Is it possible for a certain electrical circuit of a car take MORE power than it's supposed to? Say for example something's supposed to normally use 0.25volts, but for some reason it's draining 2.0volts, is this possible? Because with my car, stepping on the brake pedal has always caused a large drop in voltage, like 2.5volts. And why is that when you're at a complete stop with your foot on the brake, it takes way more voltage than when I put the car in park? Is this normal? Do all of your cars give better voltage readings when the car is idling in park versus idling in drive? THANKS:o) Quote Link to comment Share on other sites More sharing options...
bumping z34 Posted October 13, 2002 Report Share Posted October 13, 2002 Hi and welcome to the wonderous world of W-body cars let me be your tour guide, My name is brennan and yes our cars do some strange things LOL Quote Link to comment Share on other sites More sharing options...
Brian P Posted October 13, 2002 Report Share Posted October 13, 2002 Because with my car, stepping on the brake pedal has always caused a large drop in voltage, like 2.5volts. And why is that when you're at a complete stop with your foot on the brake, it takes way more voltage than when I put the car in park? Is this normal? Do all of your cars give better voltage readings when the car is idling in park versus idling in drive? THANKS:o) Well, 2 things while in park....1- idle is a hair higher, for example my car idles around 650rpm's in drive, but about 750 in park. 2- basically this causes the drop in RPM's is that the transmission is not putting a load on the engine. Let me ask you, have you checked the tightness of the battery terminals and that theyre corrosion free? I had a loose negative terminal once, and the only problems it caused are a heavy voltage drop when the brakes were applied or the cooling fans came on...so much that the headlights momentarily blinked. Quote Link to comment Share on other sites More sharing options...
GnatGoSplat Posted October 13, 2002 Report Share Posted October 13, 2002 Actually, you don't measure drain in volts, drain is measured in amps. Everything in the car uses 12V (or whatever the battery/alternator is putting out). However, the variable is current. Some things drain more current. The only time a current drain results in voltage drop, is if the power source is too weak to supply the current needed. So if stepping on the brake pedal causes voltage to drop 2.5V, that's due to the battery or alternator being unable to supply enough current to keep the voltage steady. Quote Link to comment Share on other sites More sharing options...
chronic139 Posted October 13, 2002 Report Share Posted October 13, 2002 my car does the exact same thing but it only started after I did the alternator. (I Think) Could it be that I got a bad Alt.? Quote Link to comment Share on other sites More sharing options...
NORBI Posted October 13, 2002 Report Share Posted October 13, 2002 MY car used to do the same and what the cause was a loose negative cable on the battery and positive bable that goes next to the fuel pump fuse was loose, i tightned both of them and problem went away. Quote Link to comment Share on other sites More sharing options...
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