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Old 09-18-2017, 12:04 AM   #1
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I need a little help if anybody has ever encountered my problem.

I have a 2008 silverado 1500 with the 4.3 gas engine and the 4L60E transmission. It has thrown up the PO976 code for "shift solenoid b control circuit low". Shifting is erratic and late, if it shifts at all. Sometimes it will shift but only after taking my foot off of the acelerator.

I checked the transmission fuse and it was indeed blown, however changing the fuse did not solve the problem. The code would still come back after I cleared it. The fuse has not blown again and is still good.

I checked the wiring harness at the computer and at the transmission. it is good.

I dropped the transmission pan and changed out the shift solenoids. However, the old solenoids were both good. They both measured the correct resistance and they both actually worked when I applied power on my test bench.

The solenoid wiring harnesses both have power, and a resistance check on the negative harness wire shows that I don't have a ground in the wiring.

All this, along with the fact that my transmission never entered "limp mode" even tho it should have with the solenoid not working makes me think the the tcm may be bad. Does anyone have any advice?

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