how do i reset transmission cvi?

jon0m0berry · Mar 27, 2017

got a line pressure booster and its working great, but it keeps giving me a check engine light, something like p9033. saying pressure is to high. but that's the point of the sonnax line booster. I keep reading the cvi needs to be reset. ive tried driving for about a week now but it seems like it just isn't resetting. I do have a diablo i2 tuner but cant seem to find anything that could reset the cvi....if there even is an option to do so with the tuner. is there anyway to get this done so my truck doesn't think its got a problem.

Tach_tech · Mar 27, 2017

You could try disconnecting the battery for 30 mins but usually clutch volume indexes have to be reset with a scan tool.

yoda · Mar 27, 2017

Disconnecting battery will not reset CVI you need a scan tool that can perform trans quick learn.
Not sure how doing that is going to get rid of your line pressure high code though.
It's probably setting line pressure high code because your line pressure is high.
How does this booster work? Does it just plug in between the trans line pressure sensor electrical connector and the sensor?

yoda · Mar 27, 2017

I just googled it. I'm assuming they are just adding a resistor so the line pressure sensor is lying to the pcm. Giving it a lower line pressure sensor voltage thereby causing the PCM to raise line pressure.
The Resetting CVI is needed because with more pressure filling the clutch pack, it will take less time for the pack to fill.
Maybe you got a defective one. Or your line pressure sensor was on its way out and by messing with it **** the bed.
Are there reputable trany builders recommending these? Sounds like a bad idea to me

Tach_tech · Mar 28, 2017

yoda said:
I just googled it. I'm assuming they are just adding a resistor so the line pressure sensor is lying to the pcm. Giving it a lower line pressure sensor voltage thereby causing the PCM to raise line pressure.
The Resetting CVI is needed because with more pressure filling the clutch pack, it will take less time for the pack to fill.
Maybe you got a defective one. Or your line pressure sensor was on its way out and by messing with it **** the bed.
Are there reputable trany builders recommending these? Sounds like a bad idea to me

You're right that needing to reset the CVI for the increased line pressure should be done. The CVI would not be causing the line pressure code though as you said.

CVI is for adaptives so that the transmission can maintain shift quality through out the lifetime as the transmission ages. CVI will effect shift quality but will have nothing to do with a high line pressure code. Either the booster is causing line pressure to go beyond the max pressure or there's something else wrong. Like the sensor,wiring,PCM/TCM, or internal to the transmission.

I honestly can't see something like that being a good idea unless you're actually racing it and you're trying to firm up the shifts. Even then just boosting line pressure isn't the way to do it.

jon0m0berry · Mar 28, 2017

it still shifts fine. better if anything. if I drive like a grandma it wont come on, but once it give it any real gas it comes on. but still feels like its shifting great

Tach_tech · Mar 28, 2017

jon0m0berry said:
it still shifts fine. better if anything. if I drive like a grandma it wont come on, but once it give it any real gas it comes on. but still feels like its shifting great

Line pressure is going to increase with engine load. What was the reason for installing the booster?

how do i reset transmission cvi?

jon0m0berry

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