99 Sunfire 2.2L overheating

1999 PONTIAC SUNFIRE
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JETSTREAM
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  • 6 POSTS
I have a 99 Sunfire 2.2L no A/C, Auto and 105,000Km.

The cooling fan is not turning on at all. The fuse, the relay, the coolant temp sensor, and the fan itself have been checked and work perfectly. I have also checked the circuits for the coolant temp sensor and the fan and they to check out okay.

However when I unplug the coolant temp sensor (with the engine running) the cooling fan comes on right away. My guess is the PCM.
Anyone have any other ideas?
Sep 1, 2007 at 4:37 AM
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RASMATAZ
  • ✓Experienced Mechanic
  • 75,992 POSTS
The PCM commands the cooling fan by grounding the relays. Its a lot cheaper just to hot wire the fan motor than to replace the PCM by using its power source and ground.

Good luck.
Dec 9, 2018 at 12:40 AM
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JETSTREAM
  • MEMBER
  • 6 POSTS
Thank you for your quick response!

I take it from your reply, that the PCM is the problem then. Thanks for the tip on hot wiring the fan but I have sourced a PCM from a wrecker for very cheap ($60.00 and tested).
Dec 9, 2018 at 12:40 AM
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