Attention: TDR Forum Junkies 
I took my truck to the dealer for the 5th time and really twisted his arm to get my fast idle turned on. They initially would not believe me when I told them there was such a thing. When previous attempts to get it turned on failed, I asked them to call the STAR techline. They refused to call because "We know these trucks better than you do, and there is no such option!" On December 26th I insisted they call STAR. That was when the service writer told me they don't like to call STAR because the STAR techs talk down to them like they are idiots. I was very diplomatic and did not say what might seem obvious to most of us. 
They didn't want to bother with this because Tennessee isn't that cold. Then I reminded him that several people in this world travel every so often and therefore don't always park at home. I have friends in New Hampshire and our oldest daughter has relatives in Alaska. He didn't know how to respond to that. Then I said they were not giving their customers good service and if it was up to me, I would revoke at least two of their five stars. He finally relented and said they would call. When they did, they found that STAR was closed through the holidays. Meanwhile, I insisted that the tech look at my truck again. I had to park outside the dealership because I had the slide in camper aboard.
He did so reluctantly and complained constantly that he had been through all this and there were no such options. While he was flicking through the DRB so fast I could hardly read the screen he was saying again there was no such thing as 3 cylinder idle. Just as he said that, I spotted it. When I pointed it out, he said "Well, okay, there is one but it is disabled. " I said "Yes, but that is what I have been telling you. Click on it and enable it. " He did and then we went looking for 'Cold Fast Idle"' or something to that effect, but could not find it. On January 2nd they did finally call STAR and was told there was only the 3 cyl option to turn on.
Meanwhile, On Friday, December 27th, I took the left battery out and removed the battery box to look at the temperature supposedly under it. The sensor is in fact mounted in the bottom of the battery box in contact with the bottom of the battery. The plug for the sensor is mounted on the front corner of the box. This sensor detects the temperature of the battery to provide temperature compensation as batteries need higher charging rates in colder weather. I believe this sensor may be responsible for some of the overcharging problems some people have reported as well as the variations reported by some that their fast idle doesn't work at the same range as others. This sensor is the same range as the IAT sensor and is a negative temperature coefficient. An open sensor would be telling the PCM it is very cold and that would cause the alternator to output a higher voltage. I was only able to check my new IAT sensor and the battery sensor at 42 degf outside and 72 degf inside the house, but they agreed within 1. 5% at both temperatures.
Friday, December 3rd, it dropped to 24 degf during the night. When I started the truck Saturday morning, it idled at the usual rpms for less than one minute and then ramped up to 1 1/2 marks above the 1000 mark. This would be about 1180 rpms. I will call the dealer Monday and let them know that it worked. Maybe a little positive feedback will temper their attitude if somone else should want this done by them.
They didn't want to bother with this because Tennessee isn't that cold. Then I reminded him that several people in this world travel every so often and therefore don't always park at home. I have friends in New Hampshire and our oldest daughter has relatives in Alaska. He didn't know how to respond to that. Then I said they were not giving their customers good service and if it was up to me, I would revoke at least two of their five stars. He finally relented and said they would call. When they did, they found that STAR was closed through the holidays. Meanwhile, I insisted that the tech look at my truck again. I had to park outside the dealership because I had the slide in camper aboard. He did so reluctantly and complained constantly that he had been through all this and there were no such options. While he was flicking through the DRB so fast I could hardly read the screen he was saying again there was no such thing as 3 cylinder idle. Just as he said that, I spotted it. When I pointed it out, he said "Well, okay, there is one but it is disabled. " I said "Yes, but that is what I have been telling you. Click on it and enable it. " He did and then we went looking for 'Cold Fast Idle"' or something to that effect, but could not find it. On January 2nd they did finally call STAR and was told there was only the 3 cyl option to turn on.
Meanwhile, On Friday, December 27th, I took the left battery out and removed the battery box to look at the temperature supposedly under it. The sensor is in fact mounted in the bottom of the battery box in contact with the bottom of the battery. The plug for the sensor is mounted on the front corner of the box. This sensor detects the temperature of the battery to provide temperature compensation as batteries need higher charging rates in colder weather. I believe this sensor may be responsible for some of the overcharging problems some people have reported as well as the variations reported by some that their fast idle doesn't work at the same range as others. This sensor is the same range as the IAT sensor and is a negative temperature coefficient. An open sensor would be telling the PCM it is very cold and that would cause the alternator to output a higher voltage. I was only able to check my new IAT sensor and the battery sensor at 42 degf outside and 72 degf inside the house, but they agreed within 1. 5% at both temperatures.
Friday, December 3rd, it dropped to 24 degf during the night. When I started the truck Saturday morning, it idled at the usual rpms for less than one minute and then ramped up to 1 1/2 marks above the 1000 mark. This would be about 1180 rpms. I will call the dealer Monday and let them know that it worked. Maybe a little positive feedback will temper their attitude if somone else should want this done by them.
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