Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum banner
1 - 16 of 16 Posts

·
Registered
2008 chevy trailblazer_ls
Joined
·
468 Posts
Discussion Starter · #1 ·
Alright so long story short.. since I installed my new amp my dumbass cousin "accidentally" touched the ground and power wire together causin a big ass spark..

Since then my voltage has dropped like crazy its never constant and goes up and down up and down from 14 all the way down to about 11-12 sometimes..

At first I thought it was the new amp which was much more powerful than my older one so I ordered some 1/0 wire to do the big 3 which I'll be doing next weekend..

BUT

I disconnected my amp entirely from the main battery so nothing is on at all and I drive it around yesterday and I see the same volt drops and my lights dim like CRAZY.. like if I was bumpin full blast just by putting my windows down or whatever..

So... is there a blown fuse somewhere? Or is my truck reversed polarity or whatever.. ??

Any help would be appreciated..
 

·
Registered
2002 gmc envoy_sle
Joined
·
1,531 Posts
my best suggestion is to pull the negative on the battery and let it sit for 30 minutes or to reset everything.
 

·
Registered
2008 chevy trailblazer_lt
Joined
·
61 Posts
If I not correct I think the voltage regulator is actually built into the alternator. test to see if your battery is sitting around 12 volts when vehicle is off and then do a test when the truck is running and the meter should then jump up to around 13.8-14 volts. if it voltage doesn't change then you have an alternator failure. Good luck and keep us informed.
 

·
Registered
2008 chevy trailblazer_ls
Joined
·
468 Posts
Discussion Starter · #11 ·
your cousin just ****ed your Alternator son!!! :eek:

kick your cousins ass
lmao... funniest thing i've read today.. anyways... i did the battery reset and it worked?? i think what was wrong tho is that while disconnecting the batt, the negative was really loose.. so I was like sh*t don't tell me it was just this.. but did the reset test and let it sit for half an hour anyways.. but everything fine now so yeah thanks alot for all the input guys !! :thumbsup:

glad I don't have to replace the alt yet..
 

·
Banned
2004 gmc
Joined
·
26,181 Posts
Just for reference: the voltage regulator is built into the alternator. There are two wires going from the alternator to the PCM, however. One of them allows the PCM to monitor how hard the alternator's working to keep up with the load. (it measures the field control duty cycle, for the EE's in the house).

The other one is an inhibit line from the PCM to the alternator, so the PCM can keep the alternator from starting immediately up after you start the engine. The PCM knows the temperature, and battery voltage, and how long it took cranking to start the engine. When the oil is cold especially, it may take the PCM a few seconds to get the engine running well and the idle stabilized, and it doesn't need the added load of the alternator trying to instantly recharge the partially depleted battery. So it can inhibit the alternator for a while, and I assume it's less than a second under normal conditions. Never measured it after a long cold crank start. (I actually never get to observe a long cold crank start here. :cool: )

... while disconnecting the batt, the negative was really loose..
Don't feel badly. Some very senior people around here have totally messed up their vehicle by not noticing a loose ground until days of troubleshooting went on. Now who would that be ....... ? :woot:
 

·
Registered
2008 chevy trailblazer_ls
Joined
·
468 Posts
Discussion Starter · #16 ·
lmao was that you Majestic? Or Rodie?

anyways yeah it was a pain I actually took every single fuse in our vehicles out and checked every single one individually with a dmm.. lol took me like an hour.. after i found out how to get to the "fuse testing" mode on this complex dmm my dad let me borrow..

but anyways yeah after all that trouble I am glad to say that it stayed at a healthy 14v minimum all day today and I will still be doing the BIG 3 i believe next weekend.. should have all the parts by then.. to help out the electrical!

Once again thanks all! :hail:
 
1 - 16 of 16 Posts
Top