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Discussion Starter #1
I know this sounds like a simple fix and there are a lot of easy answers people will give me, like check the battery, does it crank. well all those were first thoughts as well. so let me set the stage a little bit. i am far from a mechanic, but i am not completely ignorant however i have no issue admitting when im lost. i am at this point, i have exhausted my skill and knowledge when it comes to this. i have limited tools and limited resources and limited patience. lol

here is the situation.
i have a 2007 Isuzu ascender 4x4 (this is the same thing as a trailblazer or envoy it was built in a GM plant), the truck only has 120k on it and is in good shape, clean and runs like a champ.

it was running just fine, then one day i went to move the truck from the driveway and i turn the key and nothing happened. the dash lights lit up but when i turned the key forward everything died. very similar to if a battery was dead. so i jumped the car thinking that was it. nope nothing. so i disconnected the battery thinking maybe it was some sort of weird code or something or anti theft or who knows. well the next day i reconnected the battery and the truck started up i was able to move it out of the drive way. so then the next day went to start it and bam nothing same issue as before. so i disconnected battery and reconnected it and nothing once again. so now i have been scratching my head and trying to exhaust my limited knowledge to try and fix it.

here is what i have done so far.

1) tried a brand new battery
2) checked and tighten all battery connections (even removed them and made sure they were clean)
3) checked the connections on the starter cables (all tight)
4) checked all fuses (no fuses were blown, dirty, or not seated correctly)
5) for good measures i replaced the starter relay
6) for good measure i replaced the ignition relay
7) replaced a few fuses just to be sure (they weren't blown but wanted to rule it out)
8) shifted gear to neutral and tried starting (nothing)
9) reset aftermarket remote start
10) tried to reprogram key thinking it was the anti-theft thing (even though the light was never on)
11) replaced the ignition switch
12) tried a different key
13) did a visual inspection to the best of my ability and didnt notice any worn, torn, chewed cables or anything like that)

so as you watch the video it shows me placing the key in the ignition, turning the key to ACC waiting until all the dash lights go out (the check engine light is the only one that remains on) then turning the key. when i turn the key forward to start it everything goes blank. no clicking under hood, no humming under hood. so i thought it wasnt getting signal out from the switch so i replaced the ignition switch (located in steering column), nothing changed. that is when i changed the starter and ignition relays thinking that may be the culprit. but nope. the video shows my continued problem.

any help, suggestions, guidance, will be greatly appreciated. my "what i would like to call Knowledge" has been tapped.

thank you kindly in advance for your assistance in this matter.


video link
 

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2004 gmc envoy_slt
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2,286 Posts
You've covered a lot of possible suspects. Try hitting the body of the starter with a hammer (just a medium tap). If it starts, you know it is the starter solenoid (need to replace entire starter). If condition is still the same, more extensive electrical trouble shooting is necessary.
 

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Discussion Starter #3
thank you i will try that when i get home from work. fingers crossed it isn't a more extensive electrical trouble shooting that is needed. my wallet cries when it hears that. lol
 

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2005 chevy trailblazer_ls_ext
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7 Posts
I know this sounds like a simple fix and there are a lot of easy answers people will give me, like check the battery, does it crank. well all those were first thoughts as well. so let me set the stage a little bit. i am far from a mechanic, but i am not completely ignorant however i have no issue admitting when im lost. i am at this point, i have exhausted my skill and knowledge when it comes to this. i have limited tools and limited resources and limited patience. lol

here is the situation.
i have a 2007 Isuzu ascender 4x4 (this is the same thing as a trailblazer or envoy it was built in a GM plant), the truck only has 120k on it and is in good shape, clean and runs like a champ.

it was running just fine, then one day i went to move the truck from the driveway and i turn the key and nothing happened. the dash lights lit up but when i turned the key forward everything died. very similar to if a battery was dead. so i jumped the car thinking that was it. nope nothing. so i disconnected the battery thinking maybe it was some sort of weird code or something or anti theft or who knows. well the next day i reconnected the battery and the truck started up i was able to move it out of the drive way. so then the next day went to start it and bam nothing same issue as before. so i disconnected battery and reconnected it and nothing once again. so now i have been scratching my head and trying to exhaust my limited knowledge to try and fix it.

here is what i have done so far.

1) tried a brand new battery
2) checked and tighten all battery connections (even removed them and made sure they were clean)
3) checked the connections on the starter cables (all tight)
4) checked all fuses (no fuses were blown, dirty, or not seated correctly)
5) for good measures i replaced the starter relay
6) for good measure i replaced the ignition relay
7) replaced a few fuses just to be sure (they weren't blown but wanted to rule it out)
8) shifted gear to neutral and tried starting (nothing)
9) reset aftermarket remote start
10) tried to reprogram key thinking it was the anti-theft thing (even though the light was never on)
11) replaced the ignition switch
12) tried a different key
13) did a visual inspection to the best of my ability and didnt notice any worn, torn, chewed cables or anything like that)

so as you watch the video it shows me placing the key in the ignition, turning the key to ACC waiting until all the dash lights go out (the check engine light is the only one that remains on) then turning the key. when i turn the key forward to start it everything goes blank. no clicking under hood, no humming under hood. so i thought it wasnt getting signal out from the switch so i replaced the ignition switch (located in steering column), nothing changed. that is when i changed the starter and ignition relays thinking that may be the culprit. but nope. the video shows my continued problem.

any help, suggestions, guidance, will be greatly appreciated. my "what i would like to call Knowledge" has been tapped.

thank you kindly in advance for your assistance in this matter.


video link
 

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2005 chevy trailblazer_ls_ext
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7 Posts
I've got a 2005 TB bought used in 2012. I had this problem about 3 times early on. Each time it corrected itself before tow truck arrived. No problems since. Never did find the problem.

Call for a tow truck. It scares the begeses out of the damn thing and it starts.
 

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2007 gmc envoy_sle
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15 Posts
Try starting the car in Neutral. Turn the key to ON, Shift to Neutral, and then try to start it. The shift linkage may be out of adjustment.
 

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My 2004 TB did this a couple of times one cold winter, after it hadn't been driven for a few months. The starter must have gummed up or something. After several movements of the key to the Start position, it started. I have been driving it regularly since then, and never had a problem again. My 2002 Silverado did the exact same thing, again after not being driven for an extended period of time. The lights may be going out because the starter is drawing a lot of current. Also, the accessories are turned off in the Start position, to allow all available power to be applied to the starter.
 

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I share your pain. I am currently trying to figure out the same situation on my 2003 TB LTZ, 128k miles.
First, I believe your dash behaviour is normal, we just never pay attention to the dash when the starter works. The instrument cluster gets power at all times so the lights and dials respond to commands to look off when turned off. It seems the engineers thought blanking the dash while cranking would be preferable. Someone out there with a 2007 TB/Envoy/Ascender could verify this, just watch the dash when it cranks. It might be quick and come right back on when the engine fires.

I've scoured the web for what can cause this no-crank and usually its not the usual battery/starter motor cause for the silence. In our sophisti-ma-cated trucks it's the PCM that has the final say for cranking. It provides a low voltage current path for the starter relay, activating the starter feed. Park/neutral switch is involved, as is the ignition switch, which both can be the culprit. But what if all observable voltages check good and the starter relay is good and no fuses are blown?

I am currently thinking the PCM is just not dropping the relay coil. If you take one of those 12v test lights and connect the clip to ground instead of batt voltage, turn the key to run then probe that PCM signal, the probe provides a current path for the starter relay and the starter cranks. The best place to probe that signal is to slip the probe under the starter relay while the relay posts still make contact in the four holes of the fuse box. This alone tests the battery, starter and the starter relay. You just need to probe the correct leg to do this test, so probe one at a time until it cranks.

Where I'm stuck is trying to find the answer to: "what does the PCM need to see before allowing the relay that current path"... Schematics look like just the purple Crnk Volt and the green PNP SIG SW, then it should drop the yellow STRTR RELAY signal. What if the first two are true but the PCM still doesn't drop the yellow wire? Bad PCM? Bad chassis ground somewhere? I'm almost ready to get a tweaked PCM from PCMofNC.com not for the extra HP but just to eliminate my original PCM as a test.

Good luck
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