BCM or ECU

Tiny
MZ.JONES
  • MEMBER
  • 2001 SATURN L300
  • 3.0L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 140,000 MILES
How do I know which is bad my BCM or my ECU? It cranks and sounds like it wants to start, but it doesn't.
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Tuesday, February 16th, 2016 AT 11:57 PM

14 Replies

Tiny
CATAFINA
  • MEMBER
Go to this link before you think! about modules: https://www.2carpros.com/articles/car-cranks-but-wont-start
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Wednesday, February 17th, 2016 AT 1:02 AM
Tiny
MHPAUTOS
  • EXPERT
Do you have any codes? Even if the check engine light is not on do a scan as not all faults will set a check light.
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Thursday, February 18th, 2016 AT 12:53 AM
Tiny
MZ.JONES
  • MEMBER
The check engine and service light does stay on and now the no security light is on as well. I can't read any codes because the code reader says it cannot connect.
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Friday, February 19th, 2016 AT 5:05 AM
Tiny
SATURNTECH9
  • EXPERT
Do you have gas gauge, fuel gauge, power locks keyless entry, can't get out of park etc? Please give any symptoms?
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Friday, February 19th, 2016 AT 7:17 AM
Tiny
MZ.JONES
  • MEMBER
I don't have keyless entry. And my gauge is on E and the gas light is on and I know that I have at least a half tank. Yes, I can move it out of park.
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Friday, February 19th, 2016 AT 9:18 AM
Tiny
SATURNTECH9
  • EXPERT
If it is not running your check engine light will be on and service light as well. With the gas gauge not operational and the security light is on it sounds like a bad bcm. I have seen bad bcms cause you not be able to link to the ecms on those cars. The fuel gauge operational and not starting is a common symptom on those cars when the bcm's go bad. I replaced a lot of bad bcm's on those cars when I worked at the Saturn dealership. I have tester bcm's for all the years saving all the old bcm's I replaced.I would just swap it for my tester and see if the symptoms changed to see if I had a bad bcm.
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Friday, February 19th, 2016 AT 10:40 AM
Tiny
MZ.JONES
  • MEMBER
The security light is not on. Just the check engine soon and service and my gas light. It was driving fine just a few days ago.
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Friday, February 19th, 2016 AT 2:23 PM
Tiny
SATURNTECH9
  • EXPERT
With the gas gauge not operational and not starting plus not talking to the ecm you could have a bad bcm. I have replaced a lot of bcms for those exact same symptoms.
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Friday, February 19th, 2016 AT 3:13 PM
Tiny
MZ.JONES
  • MEMBER
Thank you I will let you know what happens.
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Friday, February 19th, 2016 AT 3:47 PM
Tiny
SATURNTECH9
  • EXPERT
EBay offers a repair service for bcms way cheaper and you don nott have to have the bcm programmed like if you replace the bcm.
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Friday, February 19th, 2016 AT 4:32 PM
Tiny
MZ.JONES
  • MEMBER
I replaced the bcm and still no start ;(
Now I smell gas and before I didn't. So I also checked my fuses and none of my ignition fuses light up I've even changed them. What would make all my ignition fuses not light up when tested?
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Sunday, February 21st, 2016 AT 6:48 PM
Tiny
SATURNTECH9
  • EXPERT
When you say you replace the bcm, was it used or new? Also where was the bcm located?
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Sunday, February 21st, 2016 AT 6:50 PM
Tiny
MZ.JONES
  • MEMBER
It is a used one. The car I took it from was running before I took the bcm out. And it is on top behind the glove department on both cars. I'm stuck I haven't had the car but a few weeks, so I don't really know too much. However, when removing the bcm this car had had the bcm replaced before and there was black tape on the wires. I coud add pictures later today. But other than this its driven great just minor front end repair.
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Monday, February 22nd, 2016 AT 12:19 PM
Tiny
SATURNTECH9
  • EXPERT
Just because there is tape on the bcm wires doesn't mean the bcm was ever replaced. Post a picture of your old bcm with the used bcm. Does your gas gauge work? When you replaced the bcm with a used one did you relearn the pass lock sensor? If not the car won't start with the bcm you swapped it with.
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Monday, February 22nd, 2016 AT 12:43 PM

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