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Anti theft problem

Old Nov 12, 2025 | 10:29 AM
  #31  
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Originally Posted by 650Hawk
My money is on the aftermarket alarm/remote start, or the fuse box not being correctly seated.
I never took the box off before having that issue or the rebuild I just took it off recently , but what the remote start had to do with it starting?
 
Old Nov 12, 2025 | 11:45 AM
  #32  
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Originally Posted by 650Hawk
My money is on the aftermarket alarm/remote start, or the fuse box not being correctly seated.
why you think the remote start? You think it’s preventing it from starting!?!
 
Old Nov 12, 2025 | 01:48 PM
  #33  
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it usually uses a relay that depending on how it is installed might be cutting the ignition power if the alarm is disabled. in that case you have to find the added relays and reconect the factory wiring they might have cut and patched into.
 
Old Nov 12, 2025 | 02:50 PM
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Originally Posted by bronxteck
it usually uses a relay that depending on how it is installed might be cutting the ignition power if the alarm is disabled. in that case you have to find the added relays and reconect the factory wiring they might have cut and patched into.
I put a new crankshaft sensor and no go. I removed the remote start and put the wires back to factory and still doesn’t start . But what I found out that the cams sensors pushing too much voltage. I’ll run more tests when I get back home and update
 
Old Nov 12, 2025 | 06:01 PM
  #35  
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Originally Posted by NFS
I put a new crankshaft sensor and no go. I removed the remote start and put the wires back to factory and still doesn’t start . But what I found out that the cams sensors pushing too much voltage. I’ll run more tests when I get back home and update
I am gonna lose my mind! Still no reading from the crankshaft sensor!!! What am I doing wrong!? What’s going on? I been trying to figure this out for 2 weeks now!!! Any suggestions!!!
 
Old Nov 12, 2025 | 06:12 PM
  #36  
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Do you think it’s my wire harness just broken that’s why it’s not reading signals from the crankshaft ?! I mean I tried 2 different crank shaft sensors and I am also getting the one that someone did the built tried and recommended and if that still not reading should I cut the plug and wire a new one? Or should I get a whole new wire harness??
 
Old Nov 13, 2025 | 03:54 AM
  #37  
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If you’ve tried two different sensors and are still not getting a reading from the crank sensor, then I would switch gears and look into the wires leading from the sensor to the PCM. If there is no reading whatsoever, then it’s possible the wires have failed and the PCM is not getting a proper signal from the crankshaft sensor.

If you look at the following schematic, you’ll see there is nothing in between the crank sensor and the PCM. Just two wires located on pins 17 & 18, Purple and Yellow respectively. Nothing else. No fuses, relays, etc.

I have never seen a wire connection fail at the PCM (where it attaches to the PCM), but I have seen on several occasions on my vehicles that a wire fails at an intermittent spot somewhere in between where it connects to a sensor and the PCM, which effectively turns the wire into an open circuit. If this was happening to your wires to your Crankshaft Sensor, then that would make sense why it is not providing any readings.

With that, I would now start by disconnecting the battery completely and disconnecting the 3x connectors to the PCM. Now you’ll have to trace back the crankshaft sensor wires to the appropriate connector to the PCM; I’m 99% sure it is the MIDDLE connector to the PCM, based on schematics I can find online, but I’m out of the country now so I can’t verify with my own vehicle.

Either way, look for a yellow and a purple wire on pins 17/18, next to a white/black and an orange/black wire (pins 19 & 20 respectively). Then, look for a space between the crankshaft wires, then look for pins 14/15 which are a pink/black wire and a light blue wire. If you fine pins 19/20 and 14/15, the crankshaft wires should be the 17/18 pins which are yellow and purple.

Once you’ve made absolutely sure you’ve found the right wires to the crankshaft sensor, now take your multimeter, put it on resistance mode, and test the wires resistance from where it connects to the PCM and where it connects to the crankshaft sensor. You may have to get creative, or get a second set of hands since you’ll be on the passenger side of the vehicle and the crankshaft sensor is on the opposite side, but bottom line you’ll need to test the resistance of those two wires.

If the resistance of the wires reads zero (or close to it), then the wires are okay and this is obviously not your problem. However if the resistance of one or both of the wires is infinite, or very high, this indicates the wire has failed and will need replacing.

Make sure you’re using a fairly quality multi-meter. I’ve never had good luck with the $7 ones that Harbor Freight sells. Lots of erroneous readings from them.

If you’re having a hard time getting the multimeter probes into the PCM connector to measure the resistance, then it may be easier to cut the wire about 6-8 inches from the PCM connector, strip it, and measure the resistance of the wire that way, the reconnect them back together when you’re finished.

If the wires check out good, then this is obviously not why your crankshaft sensor is failing to give readings. If one or both of the wires check bad, then they will obviously need replaced.

I’ll stop here for now; try this and let us know what happens.

Schematics/pictures attached.
Schematic
Schematic
Schematic; look where the Crankshaft sensor meets the PCM, via a purple and yellow wire.
Schematic; look where the Crankshaft sensor meets the PCM, via a purple and yellow wire.
I’m almost positive the crankshaft sensors meet in the middle connector, but don’t quote me.
I’m almost positive the crankshaft sensors meet in the middle connector, but don’t quote me.
PCM; taken from a 2008 H3 so may look slightly different than your 2007, but this is the best I could do while being out of the country. <img src=" class="post_inline_image" data-size="2000x1504" data-src="https://cimg4.ibsrv.net/gimg/www.hummerforums.com-vbulletin/2000x1504/img_8859_1554691613c8d0161c7bd5a04bc5c74a76b525a0.jpeg" loading="lazy" />
PCM; taken from a 2008 H3 so may look slightly different than your 2007, but this is the best I could do while being out of the country.
Wires uncovered, again from a 08 Alpha. If you have to snip one of the wires, I would do it in this fashion (giving yourself about 6-8 inches to safely reconnect the wire).  Don’t test the white wire as shown here (I was testing something else); look for the yellow and purple wires from the middle connector on pins 17/18 instead.
Wires uncovered, again from a 08 Alpha. If you have to snip one of the wires, I would do it in this fashion (giving yourself about 6-8 inches to safely reconnect the wire). Don’t test the white wire as shown here (I was testing something else); look for the yellow and purple wires from the middle connector on pins 17/18 instead.

 
Old Nov 13, 2025 | 06:52 AM
  #38  
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Thank you a lot for the explanation I will def check that next as the wire now is the suspect I ordered a new crankshaft connector that I will cut and hook just for the sake of eliminating that option but I’ll go head and trace it. I have a good multimeter It have the option where to check to see if the wire circuit it complete it will beep also so I’ll check that too .

so you said it’s in the middle pcm I just need to find the right pin and I’ll test it
 
Old Nov 13, 2025 | 07:06 PM
  #39  
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I checked wire all the way to pcm I am getting ohm 0.5 and beeping for both wires. The circuit is perfect . So I cut the connector because I have a new one coming tomorrow. I strip the wire and hooked up the multimeter and checked ac while cranking and it only goes to 0.11 while cranking so does that mean this new crankshaft is wear or bad too!!?? Online and AI saying that pcm needs 0.3 to 0.7 to fire up is that true??? I am waiting for the one from Amazon that the other guy had to try tha one to see if it will work
 
Old Nov 14, 2025 | 09:28 AM
  #40  
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are you sure you have the right cam for your head? diffrent years have diffrent sensor positions. some have one sensors some have 2.
 

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