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2007 yukon 5.3 NO Crank

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Old Jan 25, 2016 | 08:38 AM
  #11  
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I did swap relays with other ones . The Fuse "appears" fine however i didn't test it as this started as an intermittent issue . Ground , i tested to engine ground good , to chassis ground good
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Old Jan 25, 2016 | 11:04 AM
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I provided the information you need. Get your meter out and start probing. I suspect maybe some loose wiring under the underhood fuse box.
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Old Jan 27, 2016 | 07:09 AM
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yes thank you for the schematics ! definately gives me a better understanding .If i read it right, coming off the fuse going straight to the starter .i have had the under hood fuse box out 3 times looking for corrsion/bad wires etc.... ongoing
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Old Jan 27, 2016 | 09:49 AM
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is there a schemtaic of the ecm available ?
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Old Jan 27, 2016 | 10:51 AM
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big mistake , i do not seem to have switched power through the relay . I have constant power to it nothing out
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Old Jan 27, 2016 | 11:26 AM
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See if you have anything going in or coming out of the ignition switch... If you do you need to see if its coming out of the bcm...
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Old Jan 27, 2016 | 02:19 PM
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yes have column half apart need a wire dia on it to confirm power out (ther switch is switching some things such tb etc.... its killing lights when in crank mode..)
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Old Jan 27, 2016 | 02:29 PM
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Originally Posted by 6kimages
big mistake , i do not seem to have switched power through the relay . I have constant power to it nothing out
Where do you see switched power on the starter SD? You have +batt 12V going through a 175A Mega fuse then to one side of the relay contacts. Pull the relay and See if you have +12v on relay socket 30. If you do jumper relay socket 30 to 87. Does starter turn? If not you have an open between relay socket 87 and starter. If starter turns then you have a bad relay, or an open ground on relay socket 85 or pcm is not putting 12V on relay socket 86 when key in crank position.
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Old Jan 27, 2016 | 04:24 PM
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yes starter turns when jumpered , other relay in place makes no difference . Ig switch (what i think is the connector at the switch has 5 wires. no key on 2 wires are at 5 v when switched one goes to 3 v (approx) other stays the same. 3rd wire constant 12v. next two go from 0v to 12 v with key switched. nothing to compare this too but assume 2 going to 12v it likely is good and assume they go to BCM but ???? and i really do appreciate the guidance on here
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Old Jan 27, 2016 | 04:26 PM
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Originally Posted by Wolftrk99
See if you have anything going in or coming out of the ignition switch... If you do you need to see if its coming out of the bcm...
anything to what group/wires i could check on the bcm?
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