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Go Back   Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum > 2002 - 2009 TrailBlazer/Envoy Tech > 02-09 Vortec 4.2L I-6 Engine and Drivetrain > OEM Issues

OEM Issues Original Equipment Repairs and/or Problems

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  #1  
Old 03-05-2012, 06:41 PM
MitchPower MitchPower is offline
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2002 Chevy TrailBlazer LT
Pewter Metallic 4.2L I6 AWD
Join Date: Feb 2010
Location: Trois-Rivieres, Canada
Posts: 4
Flickering lights

Hi everybody
sorry to post another thread for this but I read many threads but haven't found the same exact problem or a solution
I changed the alternator on my 2002 TB because the bearing went bad then few days later I notice the lights(head,dash and dome) were flickering I didnt care much but then the blower, cruise stopped working and the abs lighted up so I changed the ignition switch but it didnt solved the flickering problem figured the rebuilt alt voltage regulator was bad so I got another one but still the same.

the voltage at the battery at idle is 15v...according to the dash its going from 15 to 17.5 at idle and at 2000rpm its at 17v at the dash but still 15v at the battery

I cleaned up the ground 102 and 201 and battery terminals BUT THE FLICKERING IS STILL THERE @#%$?&?%&

Anyone has any idea?is there a chance that the second alt is bad too?

thanks for help
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  #2  
Old 03-06-2012, 01:10 AM
sixholdens sixholdens is offline
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2002 Chevy TrailBlazer LS
Midnight Blue Metallic 4.2L I6 4X4
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Describe the "flicker". Is it only when the vehicle is moving or is it tied to the alternator on/off cycle? What else is cycling if anything? I'm leaning toward a bad connector or ground that is common to all these systems.
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  #3  
Old 03-06-2012, 05:41 PM
MitchPower MitchPower is offline
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2002 Chevy TrailBlazer LT
Pewter Metallic 4.2L I6 AWD
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no problem until the engine is started but after that theres no real pattern sometimes it will be ok as i cruise on the highway at 2000rpm until i let go of the gas but other times it only goes faster as the rpm increases
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  #4  
Old 03-06-2012, 05:53 PM
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Ralph_T Ralph_T is offline
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17.5 volts? Yeah that would seem a bit too high. 14.5 to 15 volts is normal. But I wouldn't go by the dash. Go by the reading with a voltmeter across the battery terminals.
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  #5  
Old 03-06-2012, 06:19 PM
MitchPower MitchPower is offline
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2002 Chevy TrailBlazer LT
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Quote:
Originally Posted by Ralph_T View Post
17.5 volts? Yeah that would seem a bit too high. 14.5 to 15 volts is normal. But I wouldn't go by the dash. Go by the reading with a voltmeter across the battery terminals.
yeah the voltage at the battery is 15v even if the dash waves between 15 and 17
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  #6  
Old 03-07-2012, 05:27 PM
MitchPower MitchPower is offline
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2002 Chevy TrailBlazer LT
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Alright I managed to check the truck a bit more this afternoon and I got a bit more details on the problem

it's not a bad ground between the engine and the battery

when I unplug the connector on the alternator the problem stop but it isnt charging either

the continuity on both wire is good

if the grey wire(fied duty cycle) is disconnected it charges but it also keeps flickering and if the red(generator on signal) is removed it stop charging and it also stop flickering

so I guess the problem is coming from the pcm..maybe a bad ground on the pcm...could also explain my bad mpg problem thats been going on for a while maybe a sensor is also suffering from that bad ground
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  #7  
Old 01-12-2013, 10:08 PM
mcnea001 mcnea001 is offline
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2005 Chevy TrailBlazer LS
Silverstone Metallic 4.2L I6 4X4
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Any update?

Quote:
Originally Posted by MitchPower View Post
Alright I managed to check the truck a bit more this afternoon and I got a bit more details on the problem

it's not a bad ground between the engine and the battery

when I unplug the connector on the alternator the problem stop but it isnt charging either

the continuity on both wire is good

if the grey wire(fied duty cycle) is disconnected it charges but it also keeps flickering and if the red(generator on signal) is removed it stop charging and it also stop flickering

so I guess the problem is coming from the pcm..maybe a bad ground on the pcm...could also explain my bad mpg problem thats been going on for a while maybe a sensor is also suffering from that bad ground
I just started having this problem with my 2005....I can't find out what the solution is. It is all over the web...but no single fix....ugh.
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  #8  
Old 01-21-2013, 11:42 AM
Bryan_ Bryan_ is offline
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2005 Chevy TrailBlazer LS
Dark Gray Metallic 4.2L I6 4X4
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I'm having a similar problem as well. But it's only when letting off the gas and coasting to a stop (such as when approaching a stop light or stop sign). If I wiggle my steering wheel ever so slightly back and forth while coasting straight or slightly applying the brakes, I can get my headlights to sometimes flicker.

It seems to be something in the steering column (maybe?) as I can sometimes get it to go away if I adjust the tilt in my steering and leave it there. When it resurfaces I readjust the column and wait it out again. I know that's no solution, so not that I have the time I want to tackle it. Little bit worried about tearing apart the steering column though. Wondering if a wire harness is grounding out or something.

No other lights flicker, just the headlights.
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  #9  
Old 01-23-2013, 09:39 AM
tmr91 tmr91 is offline
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2006 Chevy TrailBlazer LS
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I believe I am having a similar problem. I have a 2006 TB. I have noticed that when I come to stop light, you can see and hear the engine rpm raise and lower approx 200-300 rpm and at the same time the head lights will dim in sequence with the engine rpm. The blower motor will also change it's output as the engine RPM's drop. The voltage at this point is down around 12 - 14 volts and the dash lights dim way down. The system appears to be charging and will run fine when at highway speeds. The only way to stop all of this is to turn off the head lamps, say in the morning if I start the vehicle to warm up or just turn on the parking lamps.
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  #10  
Old 01-23-2013, 12:02 PM
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Ray Dockrey Ray Dockrey is offline
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2009 Chrysler PT Cruiser
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Have you had your battery checked?
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