P1860

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Rally

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1999 Tahoe 190k miles 5.7L 4L60E
Codes: 1860, 1870, and bank 2 lean code
I got the exhaust repaired, crack near front right oxygen sensor, complete break before aftermarket 2 into one muffler, complete break after muffler to fixed with just a Y pipe for now until I get a muffler or just a stock cat back exhaust. I reset the computer by disconnecting the battery for a minute; that made it louder for some reason. After a couple days of use I got the three codes listed, cleared them and got just the 1860 code listed twice. I had a noticeable vibration about a year ago; after replacing the rear driveshaft and it's u-joints it was better. (The driveshaft had hammer shaped dents near u-joints, not very deep roughly 1/8" deep at worst. Newer u-joints found in old driveshaft that were tight but it actled like a nice new tight u-joint not like a stuck u-joint or a loose u-joint.) The vibration is back but only past 65mph and not as strong. I replaced the front u-joints since one was stuck and that removed the vibration for a day but it returned. (The front driveshaft doesn't appear to have dents.) When the check engine light is on I loose more speed on the hills and take longer to get up to cruise speed. Is there a good way to check the resistance of the TCC Solenoid? I can do it with the transmission pan off but I'm hoping there's a connector up by the computer I can check. I read it should be 10-11 ohms, is that correct?
 

east302

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Here’s the diagnostics for a 98, maybe it’ll be close enough for a 99. It references a Kent Moore harness (J-39775) for testing. Sometimes you can get a good deal on used Kent Moore tools on eBay, but a quick Google search returned this post from someone that managed to test without it:


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NickTransmissions

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P1860 is TCC lock up solenoid assembly and P1870 is more than likely TCC regulator valve in the valve body. Replace the wiring harness and install Fitzall's TCC reg valve for 1995-2000 4L60Es into the VB and that should fix the problems behind those two codes.

1999 Tahoe 190k miles 5.7L 4L60E
 

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