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Discussion Starter #1
Good Morning. I'm a long time user, first time poster. Been searching but haven't found previous posts that address my issue. I have a 1999 7.3 4X4 Crew Cab Long Bed 4R100 trans, 350,000 miles. At idle, the RPMs drop to about 500. Feels like the torque converter is trying to lock up. The idle then jumps back up to 800 or so, back down to 500 and so on until acceleration. Does it in drive and reverse, not in park. Sometimes, the shift from 1st to second is a hard bang. Transmission rebuilt 3 months ago. Had Code P1746 after rebuild, transmission shop warrantied the coil pack but symptoms are the same. Thank you for any advice and help.
 

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Was this occurring before the transmission rebuild? Low fluid pressure can cause the TC to lock. Low fluid is a frequent cause. Loose feed bolts are also a cause. Both should have been resolved with a rebuild.
 

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Discussion Starter #3
Yes. This was a problem before the rebuild, other issues also triggered the rebuild though.
 

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Unplug the ICP sensor and see if anything changes at idle.
 

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Thank you for responding! The ICP is new. Noticeable change when unplugged. Code reader shows several codes for Generic Electric Module. But I think these codes are bogus. The things it is complaining about are working. Like Wiper Select switch Failure, Interior Courtesy Lamp Failure etc. I'm starting to think I have a short somewhere or a bad PCM.
 

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Does it run better unplugged? You may have a bad sensor. Was it an International part or aftermarket?


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