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2009 CTS
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I have an 09 CTS with DI engine. Last night my car got a CEL and when I got it checked today and its code P2601. I found other caddy's codes (SRX/STS) and they both call out the Aux Water Pump, but couldn't find anything in CTS thread. Before I change out the aux pump, I'd like to shoot the wiring and make sure its all good/not grounded and also the relay but I've looked at both fuse boxes and the manual and couldn't find a relay or fuse. If anyone can can tell me what/where the pump connects to or which fuse/relay. It would be wonderful, if not I suppose I can just change out the pump and hope the code goes away.

By the way, the car runs fine and in 105 degree temps outside, the car temp remains the same as before the light illuminated.

Brian
 

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Black Ice 2009 CTS 3.6DI 6SPD Premium
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I really hope someone has a test procedure for the Aux Coolant Pump. I have replaced it twice but after about a month the P2601 CEL issue returns. I can tell when it is going to happen because the A/C starts to blow hot air while idling at a stop light. I am concerned that the issue is not the pumps but actually a wiring or fuse issue. Any help would be appreciated.
 

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I really hope someone has a test procedure for the Aux Coolant Pump. I have replaced it twice but after about a month the P2601 CEL issue returns. I can tell when it is going to happen because the A/C starts to blow hot air while idling at a stop light. I am concerned that the issue is not the pumps but actually a wiring or fuse issue. Any help would be appreciated.
Have you checked your coolant for proper level?
 

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Have you checked your coolant for proper level?
Yes... but, I am waiting for the car to cool down. I was running errands and the A/C started weakening while idling... I was just blocks from my home and the temperature gauge shot up. I shut off the A/C and it came back down to normal. I parked it and will look at things in the morning. I will give you an update.
 

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'14 CTS-V LongRoof; '16 ATS-V Sedan,' 04 Trailblazer 4x4; '10 CTS LongRoof gone but never forgotten
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Padgett, how many miles have you put on your coupe in that time frame?
 

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08 CTS DI
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I can tell when it is going to happen because the A/C starts to blow hot air while idling at a stop light.
I was running errands and the A/C started weakening while idling... I was just blocks from my home and the temperature gauge shot up.

That's not related to the aux water pump because it does not operate while the motor is running. It is not activated until after engine shut down. Your symptom descriptions sound like a cooling fan issue, poor A/C at a stop, fine when the car is moving (air moving through the condenser). I believe the 08 is the only second gen that has dual cooling fans, if you have a single fan, check its function, if it's not running full blast at idle under this circumstance, or at all, either the resistor is damaged, or the fan motor is bad, resulting in poor to no performance at idle. The condenser gives off a lot of heat with the A/C running, so yes, turning it off will help improve engine cooling.
 

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2002 F55 STS, 2014 Explorer XLT, F-150s
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For most vehicles with electric cooling fans there are two modes of operation - FAST or SLOW depending on coolant temperature (ECT/PCM control) and SLOW when any A/C compressor function is set (PCM control) - not for engine cooling - but to insure airflow through the A/C condenser at low speeds - as referenced above. In many vehicles the electric fan(s) don't run above 30 mph or so - not needed.
 
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