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Crank sensor issue

Tiny
LAVAR CARRUTHERS
  • MEMBER
  • 2005 PONTIAC G6
  • 3.5L
  • V6
  • FWD
  • AUTOMATIC
  • 285,000 MILES
My car had a bad rod bearing so I went to a local salvage yard and found a 2008 Pontiac G6 with only 85,000 miles on the engine. So I put it in my car (listed above) and got everything hooked up and working except the crank sensor. The ECM is not receiving any input and I am not sure if the sensor is not compatible with the old computer. So I swap sensors from the old engine and still no signal what could be the problem be. I have a pretty good idea on how crank sensors were, but they both fit in the engine and plug in to the socket. However, the computer does not pick up a signal from either one. I tested the circuit and it is good.
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Tuesday, February 14th, 2017 AT 9:30 PM

10 Replies

Tiny
STEVE W.
  • MECHANIC
  • 12,987 POSTS
Well if the wiring diagram and other information is correct many of the sensors will not interchange. The older engine used 12 volt reference voltages, the newer one uses 5 volts. Not interchangeable.

Also, appears that both the cam and crank sensors are different types than the old ones.
Injectors, EGR, MAP, Throttle body and a few others are as well.

If you swapped over all the sensors from the old engine including the crank sensor it should run. But what I think may have happened is that the newer sensor blew internally and shorted. It may have taken out the ECM input if that was the case.
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Tuesday, February 14th, 2017 AT 10:14 PM
Tiny
LAVAR CARRUTHERS
  • MEMBER
  • 6 POSTS
Thanks. A lot that makes a lot of sense, I do not believe it shorted out the ECM input, but I do believe the older sensor is too short to reach the reluctor wheel like it should. Could that be why no signal from older sensor as well? And for experimenting purposes would it be a good idea to reduce the voltage to the new sensor to 5 volts? Or would it still not read the signal? I was able to get a response by tapping the signal wire to the positive terminal on the crank that is why I do not believe the input is ruined on the ECM.
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Tuesday, February 14th, 2017 AT 10:43 PM
Tiny
STEVE W.
  • MECHANIC
  • 12,987 POSTS
They are two different types of sensor with different outputs. Even if you lower the voltage it will not put out a signal that ECM can use. You might be able to use some type of signal converter OR see if GM used the same type output in a different use of that engine.
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Wednesday, February 15th, 2017 AT 3:49 AM
Tiny
LAVAR CARRUTHERS
  • MEMBER
  • 6 POSTS
Okay, many thanks. I pulled an engine and transmission from a 2006 Malibu maxx it is the 3.5 v6 this one should hook right up it has the EGR set up and same throttle-body.
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Wednesday, February 15th, 2017 AT 5:57 PM
Tiny
STEVE W.
  • MECHANIC
  • 12,987 POSTS
As long as it's a VIN 8 car it should fit. The part numbers on the sensors are the same at least. Keep us in the loop please.
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Wednesday, February 15th, 2017 AT 6:52 PM
Tiny
LAVAR CARRUTHERS
  • MEMBER
  • 6 POSTS
Ok will do
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Wednesday, February 15th, 2017 AT 8:28 PM
Tiny
LAVAR CARRUTHERS
  • MEMBER
  • 6 POSTS
So I install the engine today The vin number on the donor car had eight digit number eight and it started right up I just have to finish hooking up the hoses and exhaust
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Sunday, February 19th, 2017 AT 5:30 PM
Tiny
STEVE W.
  • MECHANIC
  • 12,987 POSTS
Great news. All the different brands change things around so much these days you have to really watch what parts you swap. Some are real bad and may only be a one year part.

Thank you for using 2CarPros. Com. Tell your friends, family and anyone you like about us and please return with any auto related questions, we're here to help.
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Sunday, February 19th, 2017 AT 6:26 PM
Tiny
LAVAR CARRUTHERS
  • MEMBER
  • 6 POSTS
I most definitely will again thanks a lot for your help
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Monday, February 20th, 2017 AT 12:00 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 42,913 POSTS
Please use 2CarPros anytime, we are here to help and tell a friend.

Best, Ken
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Wednesday, February 22nd, 2017 AT 2:22 PM

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