2004 trailblazer ext electrical problems

aytheregosean

Original poster
Member
Jun 14, 2015
13
Car runs and drives starts up fine,but when its started my system message lights my oil, coolant, battery and gas gauge dont rise up only only gauges that work are speedo and rpm... My back wiper or 4wd wont engage, windows wont roll down reverse lights dont come on and when im in gear my system dont tell me what gear im in like it should.
 

Mooseman

Moderator
Dec 4, 2011
25,184
Ottawa, ON
Did you recently have it jumped? Sounds like the 125A megafuse is blown.
 

kickass audio

Member
Aug 25, 2012
955
best way to check if any fuse is blown is to get a multimeter and test the resistance of the fuse. Place one end of the multimeter probe on one side of the fuse and the other end of the multimeter on the other side of the fuse. It should read as 0 ohms or very close to it. If it is anything like I (stands for infinity) or reads as open, your fuse is blown.
 
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Robbabob

Member
Dec 10, 2012
1,096
aytheregosean said:
Bump! So everyones thinking fuses?
Have you checked your fuses? You have been given a starting point. Your support will come during the next step when you report about your fuses.
 

Mounce

Member
Mar 29, 2014
13,667
Tuscaloosa, AL
We can only lend advice and guesses, you have to test what is suggested. Have you tested the fuse?

Did all of this start at the same time or did the gauges go out one by one and all of a sudden your wiper quit working?
 
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aytheregosean

Original poster
Member
Jun 14, 2015
13
All went out at the same time, have not tested the fuses yet, buying a multimeter after work, and I will get back to you guys!
 

AtlWrk

Member
Dec 6, 2011
674
The one common point for all of the failures you listed is the data bus and the way the cluster is behaving strongly points to either a short to ground, short to +battery, or one of the dozen+ modules behaving very badly and screwing up communications among all the others.
 

aytheregosean

Original poster
Member
Jun 14, 2015
13
AtlWrk said:
The one common point for all of the failures you listed is the data bus and the way the cluster is behaving strongly points to either a short to ground, short to +battery, or one of the dozen+ modules behaving very badly and screwing up communications among all the others.
So what do you suggest atl? And on the multimeter what do i set meter at to measure voltage from fuses?
 

kickass audio

Member
Aug 25, 2012
955
you don't measure voltage, you measure ohms (resistance). It is the omega symbol that looks like a headphone. Set it to either 200 or 2000 on the meter and test the resistance on the fuse. It should be 0 or very close to 0.
 

aytheregosean

Original poster
Member
Jun 14, 2015
13
So what would I set the meter at?
 

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aytheregosean

Original poster
Member
Jun 14, 2015
13
So just got done with my fuse test.. So everyone knows how the big fuses have four brongs, is every prong suppose to beep or be close to zero?
 

kickass audio

Member
Aug 25, 2012
955
those are not fuses dude, those are relays. The fuse you need to check is the one that has the big red and black wire going to it. It should say 125 on it and maybe megafuse on it as well. It is a black fuse that you can only take off by unbolting it.
 
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aytheregosean

Original poster
Member
Jun 14, 2015
13
When i touch the two silver tabs on the fuse itself its not anywhere close to zero.
 

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Mooseman

Moderator
Dec 4, 2011
25,184
Ottawa, ON
That one you test at the two posts. Best way to test fuses is by voltage. Set your multimeter to DC 20, put the black lead on a good clean ground and the red one on one post and then the other. You should have between 12-13V on both posts. If not, the fuse is blown. This method can be used

Problem with testing by continuity is that the circuit protected by the fuse could have continuity back to ground, like a light bulb, making it appear as if there is continuity. It should be used when the fuse is disconnected from the circuit.
 

aytheregosean

Original poster
Member
Jun 14, 2015
13
Mooseman said:
That one you test at the two posts. Best way to test fuses is by voltage. Set your multimeter to DC 20, put the black lead on a good clean ground and the red one on one post and then the other. You should have between 12-13V on both posts. If not, the fuse is blown. This method can be used

Problem with testing by continuity is that the circuit protected by the fuse could have continuity back to ground, like a light bulb, making it appear as if there is continuity. It should be used when the fuse is disconnected from the circuit.
I did exactly that tested both post with the fuse still in there they both read 12.52
 

Mooseman

Moderator
Dec 4, 2011
25,184
Ottawa, ON
At this point, I would suspect a faulty ignition switch. It is known to cause electrical gremlins like you reported. Not an expensive part and not too difficult to replace.
 
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