Transmission making speedometer bounce to 20mph

[Shad]

04 Chrysler Pacifica
I have had an issue with it shifting very hard out of first, off and on, for a while.
Yesterday it was humming shifting into drive very hard I was at a light and noticed the speedometer bouncing to 20mph the rpms remained at 1000, I had watched a video of Eric’s where he manually shifted to check. This car has something called autostick, I used that shifting in to 1rst and the problem wasn’t there. I only had to go a couple of blocks and was scared to try too much so I thought I would ask.

Topic

[EricTheCarGuy]

If you have a speed sensor issue, or some other issue effecting the speed sensor it will effect the way the transmission shifts. I would recommend you get a scan tool that can read live data and observe the speed signal. If it also moves around a lot then it’s likely to be a speed sensor problem or the wiring between it and the computer. If however the signal is good, then the problem is likely in the cluster.

That said there are occasions where an alternator can go bad and cause this problem. For that reason you might also want to check the operation of the charging system as well. More info here.

http://www.ericthecarguy.com/faq/solving-automotive-electrical-problems

Good luck and keep us posted

[Shad]

I washed the engine last weekend do you think there is any correlation?

I checked the alternator it was putting out 13.8v, though when I did the ground side test it seemed high in comparison to your video it was 0.08 in your video it said it shouldn’t be higher than 0.02,or maybe it was .2 I will have to watch again.

But I drove it again to “verify the complaint” and what I noticed is when stopped it jumping out of first to second gear.

Does that change any of your previous suggestions or opinions?

[Shad]

Ok, I thought I couldn’t afford a live data scanner at this time, I attribute that to lack of confidence in my abilities as a mechanic.

So I opted for the professional mechanic, it was in fact a speed sensor issue and a broken front motor mount total cost $485, being able to transport: worth it

Just wanted to let everyone know Eric’s diagnosis was absolutely correct.

Thank you

[EricTheCarGuy]

Thanks for the update and for using the ETCG forum. It’s always great when we have a solution to go with a problem.

Thanks again!

[Author]

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