# 2004 grand am gt cooling fan issue bcm/pcm

**URL:** <https://community.cartalk.com/t/2004-grand-am-gt-cooling-fan-issue-bcm-pcm/189323>\
**Category:** Maintenance/Repairs\
**Tags:** pontiac, grand-am, fans\
**Created:** [February 25, 2023, 8:09pm UTC](https://community.cartalk.com/t/2004-grand-am-gt-cooling-fan-issue-bcm-pcm/189323 "2023-02-25T20:09:34Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![unluckiest.number](https://avatars.discourse-cdn.com/v4/letter/u/958977/32.png) [@unluckiest.number](https://community.cartalk.com/u/unluckiest.number)\
**Post date:** [February 25, 2023, 8:09pm UTC](https://community.cartalk.com/t/2004-grand-am-gt-cooling-fan-issue-bcm-pcm/189323/1 "2023-02-25T20:09:34Z")

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I’m having an issue that I need to dig further with my grand am but need schematics. I’ve read that the pcm and bcm work together to turn on the low fans. The bcm had gotten wet and corroded(common issue on these) I need a schematic to rule out the bcm. I have a scan tool and can turn on the low and high fans with it. I need to know how the bcm is connected into the pcm and the pinouts. Would love to know voltages and ohm resistance as well. Thank you so much in advance!

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**Author:** ![old\_mopar\_guy](https://avatars.discourse-cdn.com/v4/letter/o/6bbea6/32.png) [@old\_mopar\_guy](https://community.cartalk.com/u/old_mopar_guy)\
**Post date:** [February 25, 2023, 8:16pm UTC](https://community.cartalk.com/t/2004-grand-am-gt-cooling-fan-issue-bcm-pcm/189323/2 "2023-02-25T20:16:26Z")

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I would recommend Helm, they have a ton of schematics.

> **[Helm Inc-Your Source for Factory Authorized Service Information](https://www.helminc.com/helm/homepage.asp?r=https:%2F%2Fwww.google.com%2F)**
>
> Helm Incorporated's online bookstore provides factory authorized automotive & motorcycle technical publications: Ford, General Motors (GM), Honda Motors, Honda Motorcycle, Suzuki, KIA, Isuzu, Hyundai

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**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\
**Post date:** [February 25, 2023, 10:37pm UTC](https://community.cartalk.com/t/2004-grand-am-gt-cooling-fan-issue-bcm-pcm/189323/3 "2023-02-25T22:37:22Z")

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![image](https://global.discourse-cdn.com/cartalk/original/3X/f/1/f1e8e387bd73f6ef8388b9961395e4c4d0af788c.jpeg)

Tester

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**Author:** ![George\_San\_Jose1](https://avatars.discourse-cdn.com/v4/letter/g/e5b9ba/32.png) [@George\_San\_Jose1](https://community.cartalk.com/u/George_San_Jose1)\
**Post date:** [February 25, 2023, 11:44pm UTC](https://community.cartalk.com/t/2004-grand-am-gt-cooling-fan-issue-bcm-pcm/189323/4 "2023-02-25T23:44:34Z")

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It appears from cursory inspection of Tester’s posting above that in low-speed mode the fans are connected in series, while in high speed mode they are individually powered in parallel, each with full battery voltage. If fans work ok at high speed mode, but don’t spin in low speed, I’d be suspecting a problem with the “Cool Fan Mode” relay (upper left) or its control signal.

Good idea w/this problem to use your scan tool to see what the OBD II computer thinks the coolant temperature is.

Note that is is often possible to find often-referenced schematics like this using Google; i.e. Google “2004 Grand AM engine fan schematic”.