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Discussion Starter #3
Ok thx. This is my go to site for help and I'm finally a part! Thx to all who post.

Ok I have a 05 trailblazer LS 4.2L I6. Im having shifting angd electrical issues and I don't know if they're related. It surges when I barely press the gas sometimes and it bogs down with my foot on the pedal. I changed shift solenoids A & B but no difference. Also my interior lights flicker and headlights switch on and off while driving.

The other day I was checking voltage from batt to mega fuse terminals and I got 1-4v fluctuations. Thinking it had to be a bad batt I tested voltage across both batt terminals and got a solid 12v. Does anyone have any idea what it could possibly be. All comments are welcome including wild guesses.

Thanks
 

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2004 gmc envoy_slt
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You need to inspect the battery connections and cables closely. Make sure battery bolts are tight. Battery cable can sometimes develop corrosion under the insulation near the terminals. Also check the negative cable ground (chassis) connection.
 

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IF someone over-tightened the battery cable bolts, they will leak acid into the connections and create a lot of electrical "mysterious" troubles like lights flashing and things that make the vehicle appear to be haunted. .

Confirm that the connections are not corroded. Personally --- I remove the plastic colored ends on all my GM sidepost connections so I can see any troubles rapidly.
 

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Discussion Starter #8
Ok thanks guys. I was just going to ask about removing the plastic/rubber from batt cables. So I can remove plastic and reconnect without it? If it is leaking a lil acid is the batt trash? What do you guys think about putting in a stronger batt?
 

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Yes... you don't need the rubbery cable covers.
Yes... if it's leaking electrolyte, technically it's trash.... BUT you can make it work for a while yet.
If you see corrosion, its damaged since sidepost batteries don't normally leak at all..
Get a good quality battery... but only if you actually need one.
You vehicle is designed for the battery it has, or will fit. Stay with the original design.
 

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2004 chevy trailblazer_ls_ext
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If it's leaking, clean the battery tray with a solution of water and baking soda. Mix it into a thin paste and cover that battery tray. Let it sit for 5-10 minutes, then wash it off. Make sure you wear rubber gloves and safety glasses when you do this. Battery acid is nasty stuff!
 

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Just don't get any acid killing potions on top of the battery. It can get into the cells through the water condensate traps and destroy the pH of the electrolyte.

I have used a big glob of clear dielectric grease to seal the electrolyte into the battery and so far, it has worked.

But I know the battery is on borrowed time.
 

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Discussion Starter #12
Ok I took plastic covers off band got a new battery since I got it in 2017. Positive cable had a little build up but nothing near what I was expecting. After reconnecting it still ran the same. I think my electronics might be even more irratic now with the new battery. The battery cables that connect to battery are slightly warped/tappered but they still went on tight. Also got new screws to connect battery.

I've looked around and heard that it could be a bad cat or ground. Even fuel pump but i have a gutt feeling better the issue is electrical. Do you guys have any suggestions on how to easily test these three items without any fancy equipment? It's starting to annoying and I really don't want to sell it.

Any help is appreciated
 

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Discussion Starter #13
Also the ground wire, that I think envoyboy was talking about, goes to a harness with other wires. Tracking it looks to be a PITA. Any suggestions on exact locations of ground connections underneath the 05 trailblazer LS?
 

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Obviously there should be no buildup of corrosion anywhere on battery connections. The reasons are obvious... it means electrolyte is getting to them.

During charging/discharging the electrolyte undergoes chemical changes that generate heat and liberation of gasses from the process.

On a top connection type battery, the mechanical placement of the cable ends puts them at high risk of electrolytic contamination because the "stills" on top of the battery (the caps) become overwhelmed and start passing vapors out of the semi-sealed internal battery environment where they coalesce, causing the diverse metals in the connection to undergo erosive metallurgical changes: corrosion.

This is the primary reason for using a sidepost battery: the cables are not in the same plane as the coalescing vapor stills, and are therefore away from the escaping vapors a battery creates in normal use activity.

Now.... along comes a "mechanic" whom should know better, vs an owner who usually has no clue ---- that while overtightening the side post bolts ruins a battery, pretty much instantly.

This is NOT "Bridge Building 1A" whereby tightening bolts, screws and screws clamps as tight as possible is needed.

Battery bolt torque is 11-12 INCH/LBS.
This is in the realm of a newborn baby fart.​
This is why GM puts a 5/16" headed x 3/8" NC bolt there... to tell you that this is "different" and is not the same as a top post where you can pretty much use a 3/4" impact gun to tighten it down (but you shouldn't do THAT either!)​

Here's an interesting insight.... LINK HERE

Twisting the bolt much more than a few inch/pounds also destroys the seal on the sidepost and will either release electrolyte or break the physical internal connection, in either case, destroying the integrity of the battery.
It WILL strip the soft lead threads inside the battery cable mount.​
It WILL destroy the internal seal.​
It WILL constantly be a problem with corrosion and loss of electrical conductive integrity.​
The vehicle WILL produce some interesting electrical/electronic anomalies (eg: haunted, possessed of evil spirits, etc).​
You can try some ingenious things to remedy this problem.

  • I've found toothpicks jammed into the threads to help the bolt stay in. That one generated enough electrical resistance to keep the starter from spinning.
  • I found steel wool in there for the same reason... but that produced so much hydrogen that an open spark could have cratered a small section of Anaheim.
  • I've found gi-normous woodscrews forced into the battery.
  • Some bright bulb used bathtub caulk to hold the bolt in.
 

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Discussion Starter #15
I tried being as careful as I could be tightening the battery cables because I stripped the the threads on the last battery. So I get what you're saying. I just tightened untill the cables were no longer loose/free. They shouldn't be loose at all right??

So you don't think it could have anything to do with the three items I mentioned before?? I even heard it could be the voltage regulator on the alt. Not really sure where to go from here?
 

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2005 chevy trailblazer_ls
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Check the battery cable connection to your starter motor (way down on drivers side of block). Mine had corroded badly over the years and when I cleaned it a lot of problems went away!
 

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2005 isuzu ascender
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I've had similar 1-4v fluctuations for short periods, usually only when higher electrical load like headlights on at night, etc. I think it's the regulator in the alternator but I've just lived with it since it's infrequent and not a big issue for me so far.
So you may want to look at the alternator itself since that drives the voltage output.

As for bad grounds, you could always just add a few extra grounds to see if it helps. It's hard to trace down every ground but no reason you can't have extra in parallel. They are all at "ground" potential anyway. Good luck
 

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Discussion Starter #18
Mine was no biggy in the beginning too but now the issues are making a drive to the carner store dangerous. For example, say it's rush hour and I'm in the center lane of a main street, like camelback, and I'm trying to make a left turn. I will most likely have to beat on coming traffic right. So as I turn and accelerate, the car boggs down losing power n speed so I slow down. CRASH! That is my biggest fear because it happens at random. I almost got T-boned by a city bus about a week ago. I'm thinking, if my car can't beat a city bus on it's normal route, I have some major issues.

Thx a mill guys I will post results as soon as I mess with it a lil more.
 

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2004 chevy trailblazer_lt
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Mr.Cant.get.right, have you had your alternator tested? I ask because I just read posts from a couple of other people (one on this board, and one another board) where the alternator had gone bad causing similar problems to what you are experiencing. If you have crappy electricity coming out of your alternator, it can cause all kinds of problems on these vehicles.
 

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Discussion Starter #20
I have not had my alt tested. I heard the same, I think it said the voltage reg. on the alt, is some what of a common issue. It gave advice to replace both but I want to be sure before I just start throwing money at it.

Any suggestions on easy ways to test the cat converter, ground integrity, and starter on an 05 trailblazer ls without any fancy equipment?
 
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