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PCM fuse continually blows

Tiny
CTDEIHL50
  • MEMBER
  • 2001 BUICK LESABRE
  • 3.8L
  • V6
  • 2WD
  • AUTOMATIC
  • 135,000 MILES
PCM fuse keeps blowing out once replaced.
Sunday, July 29th, 2018 AT 6:29 AM

28 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Good afternoon.

What is the fuse number?

There are several fuses that control power to the PCM.

Roy
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Sunday, July 29th, 2018 AT 1:00 PM
Tiny
CTDEIHL50
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  • 6 POSTS
Mini fuse # 8 PCM battery (10A).
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Sunday, July 29th, 2018 AT 2:21 PM
Tiny
ASEMASTER6371
  • MECHANIC
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Good afternoon.

That is battery control to the PCM. No other circuits that I see.

It is either a wire harness issue or the PCM itself. Unplug the PCM and see if it still blows.

Roy
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Sunday, July 29th, 2018 AT 2:26 PM
Tiny
CTDEIHL50
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I already took out PCM and battery from car. I have to get back to you about if fuse blows without PCM plugged in. Once I get battery put back in. Working on two Buick's right now.
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Sunday, July 29th, 2018 AT 2:40 PM
Tiny
ASEMASTER6371
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Okay, keep us updated.

Roy
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Sunday, July 29th, 2018 AT 2:49 PM
Tiny
CTDEIHL50
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Okay, put new fuse in installed battery and it did not blow, So I guess it is the PCM then?
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Monday, July 30th, 2018 AT 10:42 AM
Tiny
CTDEIHL50
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Sorry, I did forget to mention that the volt light comes on and stays on before and after fuse would blow and after I removed the PCM itself. I am having brain farts I guess sorry.
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Monday, July 30th, 2018 AT 11:18 AM
Tiny
ASEMASTER6371
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One issue at a time. The PCM controls the alternator as well.

Yes, you need to replace the PCM.

Roy
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Monday, July 30th, 2018 AT 12:23 PM
Tiny
CTDEIHL50
  • MEMBER
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Thank you for your help with this issue, when I get the new PCM I will let you know how it all pans out. Thanks again
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Monday, July 30th, 2018 AT 2:02 PM
Tiny
ASEMASTER6371
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You are welcome.

Feel free to follow up with any other issues.

Roy
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Monday, July 30th, 2018 AT 2:10 PM
Tiny
JYEARY91
  • MEMBER
  • 26 POSTS
I'm having a similar issue only I keep blowing the PCM, BCM, U/H relay fuse every time I try to start it. But if I unplug one of the connections on my BCM box under the steering column it won't blow but I lose headlights and a few other things.
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Thursday, April 2nd, 2020 AT 11:15 AM
Tiny
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Good afternoon.

From what you described, the BCM has an internal short and needs to be replaced.

You need a new one, not a used one as it needs to be programmed to your VIN number to be sure all your options function.

If you give me your VIN number I can get the procedure and location for you.

Roy
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Thursday, April 2nd, 2020 AT 11:19 AM
Tiny
JYEARY91
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  • 26 POSTS
Could there be an external short? I'm not at the car right now so I can't get the VIN.
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Thursday, April 2nd, 2020 AT 2:59 PM
Tiny
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If it was external it would still blow the fuse.

Let me know when you can on the VIN.

Roy
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Thursday, April 2nd, 2020 AT 3:13 PM
Tiny
JYEARY91
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It blows the fuse when I plug it in.
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Thursday, April 2nd, 2020 AT 3:35 PM
Tiny
ASEMASTER6371
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I read that before.

We are back to the BCM again.

Roy
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Thursday, April 2nd, 2020 AT 3:39 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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Hi,

Have you checked the plug itself to see if there are any pins touching that would cause a short? Also, take a look at the attached pic and let me know if I have the correct fuse that is blowing.

If I do and there is no damage to the pins in the connector, I want you to unbolt the BCM so it has no ground. If it still blows the fuse, the problem is in the wiring to it. If it doesn't, then chances are the BCM has an internal short.

Here are a few links you may find helpful:

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

https://www.2carpros.com/articles/how-to-use-a-voltmeter

https://www.2carpros.com/articles/how-to-check-wiring

Let me know.

Joe

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Thursday, April 2nd, 2020 AT 4:05 PM (Merged)
Tiny
JYEARY91
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  • 26 POSTS
Yes, that is the right fuse. So your saying look at the plug itself to see if there are any pins touching?
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Thursday, April 2nd, 2020 AT 4:05 PM (Merged)
Tiny
JYEARY91
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I'm not sure what you mean by unbolt the BCM because what I think is the BCM is just hanging down right now. I'll take a picture.
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Thursday, April 2nd, 2020 AT 4:05 PM (Merged)
Tiny
JYEARY91
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This is what I unplugged to be able to start it:
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Thursday, April 2nd, 2020 AT 4:05 PM (Merged)

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