Intermittently while driving odometer and speedometer turn off and transmission shifts hard

Tiny
ETHAN RUARK
  • MEMBER
  • 1994 FORD F-150
  • 4.9L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 178,325 MILES
Randomly while I’m driving it the odometer and speedometer will turn off and the truck will start shifting hard, sometimes I have hit the dash and they turned back on, and it would shift fine other times hitting the top of the dash does not fix it.
Wednesday, February 2nd, 2022 AT 1:30 PM

1 Reply

Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
This is most likely going to be an issue with the vehicle speed sensor issue.

The speed sensor is used for the odometer and the speedometer then also for calculating the shift points.

The way we can test this is to find out what the signal to the cluster is when this acts up.

I suspect you will find that the signal is dropping out or goes erratic. Here is a guide that will help with this testing:

https://www.2carpros.com/articles/how-to-check-wiring

However, if the signal does not alter when this happens then the issue is going to be in the cluster.

Please run through this info and let us know what you find.

Thanks
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Thursday, February 3rd, 2022 AT 2:53 PM

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