So I Hr swapped my 5th gen & my brake & battery light comes on & off time to time, could this mean my alternator is going or is there a bad ground somewhere? Can this also cause my rpm to idle below 500?

 

Let's see some pics.

What kind of voltage are you sitting at?

 

Brake and battery light mean insufficient charge, if youre idling below 500 I can see that being the problem. First thing you need to do is bump that idle up. Make sure you got no vaccuum leaks and do the throttled position and the idle relearn. If that doesn't solve it then maybe you got a dirty MAF or something. The alternator grounds through the engine, check your grounds. If you're idling between 600-800 and have clean grounds then your alternator probably needs replaced, or perhaps the belt is slipping. Test continuity between the alternator post and the positive terminal o he battery it should test good

 

So I changed my maf & nothing. Alternator is reading good & there’s no vacuum leaks. I also changed my spark plugs & nothing either. Battery & brake light comes on when it wants to & goes off. It’s weird because before the swap, my old de use to idle the same way, below 500rpm. & now with the hr swap it idles the same & the battery & brake light issue. Also When I’m cruising you can hear it break up like it’s misfiring.

 

Relearn the TB

 

bad alternator lol

 

Fun fact: the alternator won't charge if the warning light wire isn't hooked up

Your car is indicating bad alternator/battery or an issue with the power circuit maybe a bad ground. Auto stores will test the battery and alternator for free

 

Alternator is reading good & I changed my battery before & nothing. I also done a tb relearn & still nothing. I’m going to change my ground wire today, I can use a 4awg or bigger ground cable correct?

 

Do you own a OB2 tester? If so, let the OB2 tester test your electric system most have the option included in them these days! If you're simple looking at the alternator output with no load on it, the test might seem successful but once you load it down with headlights, foglights, blower fan set to full, caution lights flashing, and even the brake lights on! You will find out the truth regarding the true alternator output! If it's below 13.0 volts I would get one on order! If it's below 12.5 replace it before it burns out a battery cell causing more damage and costing more $$$$$.