Need help with electronic issue

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Aug 13, 2017 | 05:38 PM

Cody

Thread Starter

Staging Lane

Joined: Dec 2016

Posts: 62

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Need help with electronic issue

Need help guys. I have a 2001 5.7 LS in my Astro van. It is running on a Painless Wiring harness and has been on the road for a while now. The issue is with the kick down of the transmission. Occasionally I will be driving along and when I need it to downshift it won't. It up-shifts normally then when I step on it it stays in OD. When I slow down for a stop it shifts as it should then once its back in high gear it stays there. If I manually shift it to 3rd it still does the same, it wont downshift. If I give it five minuets or so it will start downshifting correctly. It does not do this every time I drive but about one out of four times. The transmission is new and only has a couple thousand miles on it. I have taken it back to the trans shop and they say it is an issue with the throttle body. I do get a trouble code erratically for the TPS (P0121). It self clears itself sometimes after a couple minuets. I have replaced the TPS twice, checked all related connectors and even put on a different throttle body. The wiring is brand new from Painless and nothing associated is less than 6 months old.

Any help is welcome guys

Aug 14, 2017 | 07:36 AM

JoeNova

Restricted User

Joined: Mar 2014

Posts: 7,192

Likes: 109

From: Ohio

You never said which transmission.

I assume 4L60e?
It needs a working TPS signal to control shift points. If your TPS signal is bad, it won't shift properly.

Seeing as how you've changed TPS, I would suspect the wiring is at fault.
Remove the TPS connector and make sure all of the pins are fully seated inside of the connector. You might do the same for the PCM side.