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06 Avalanche Starting Issue

notacos4u

Full Member
Joined
Feb 25, 2009
Messages
34
Location
Alkut, Iraq FOB DELTA The Fob of Choice, Who'
So, while driving my Avalanche, a brake line went and I lost brakes. I was able to get it home as I was pretty close and parked it. It sat for about a month and the battery died so I had my neighbor come over yesterday to bring the truck over to his garage and when he went to start it nothing. He put jumpers on it and was able to charge the battery up but still when you turn the key, nothing doesn't even make an attempt to start. The brake fluid reservoir is empty due to what we suspect is a blown brake line. Could something with the brakes, maybe a sensor, not currently working have anything to do with this and as soon as we replace the broken line and fill up the reservoir and bleed the brakes, it'll try to start? Just wasn't sure if maybe there was a sensor preventing it from starting due to the brakes. Any assistance would greatly be appreciated. Thanks
 
To my knowledge there isn't a sensor that would prevent starting but for all I know there may be one.
 
Is your security light on in the instrument cluster
 
It would look like this.

Is everything else working like the radio. fan blower, head lights.

Try swapping the starter relay with another relay, check your fuses especially IGNs fuses
 

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Also see if you can hear a click when you turn it to the start position.
 
everything seems to work fine ie radio, windows, headlights, except starting the truck. I swapped out the relays and nothing happened. We were able to start the truck by jumping the terminals on the starter. lost at where to go. Appreciate everyone's assistance and help.
 
Does your friend have a code reader, if so have him look for codes

Also have you looked at the fuses including the ones in the driver side instrument panel 
 
Did you hear the relay click when you turn the key to start.
 
Pull the headlight relay and try it.


The Body control module controls the starter relay so I'm trying to figure out if it's the wiring to the starter or your ignition switch
 
I would suspect this to be either coincidence or your battery is dead beyond recovery.
Try a known good battery first before you do anything. You can show voltage on the battery but when trying to start the battery has no power. If you have a bad battery then jump starting may not work either.

If the known good battery doesn't work...

You can test the relay.

To test the relay here is what I would suggest...

Swap the relay with another relay you know works. The headlight relay may be the same.

If one of you places your finger on the relay you should be able to feel it click when you try to start the truck.

You can also test the relay feed section by pulling the relay and using a Digital Volt meter check for +12 across pins 85 and 86 as shown on the relay diagram when you pull it out. (The relay should show which pin is 85 and 86. If not can probably pull up a diagram that shows which pin is.)

Must use a Digital volt meter and not a test light or analog meter or you can damage the BCM.

If the relay is clicking then inspect the wiring from the fuse panel to the starter. It could have gotten damaged by rodents during the month sitting.

If the relay is NOT clicking then you need to lift the fuse panel and look under it and check for mice damage.
There is a cover over the fuse panel that has to be removed then you can release the screws and possibly clips that hold the panel down and look under it.  Some members have found mice living under their fuse panels and they seem to love the taste of wiring.

If all that doesn't provide you with a good indication then I would suspect the ignition switch..
 
Step 1, swapped battery with a known good one, same issue, turn key, voltage on the dash gauge drops to zero.
Step 2, swapped relays around, there's 3 that are identical and swapped all three around and nothing changed. There is a clicking noise, but hard to tell which relay it is coming from. 
Step 3, lifted fuse box, something was storing some acorns away, but all wiring looks good there,

So with the new information, is it safe to assume it is the ignition switch and not the starter? Like I stated earlier, we were able to jump across the post of the starter and it did start the truck. I just prefer not to buy a starter if we can rule that out. Thanks for everyone's assistance.
 
Dou you have a test light or power probe?

Put a test light on the 10a crank fuse under the hood(try it on both sides of the fuse), when the key is turned to start, does the test light light? If it does then its not the ignition switch.
 
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