Vehicle speed sensor going bad?

FullForceRam · Mar 14, 2022

It appears the speedometer on my 14’ Ram 1500 2wd with a 5.7 Hemi automatic has a mind of its own.

This only happened recently almost every single time I’m on city streets or freeway, and only the speedometer drops for a split second (thus far the RPM gauge reads properly and never drops) and a message pops up on my center cluster display, but happens too fast to read it and then the Speedo goes back to my specified MPH.

I also noticed that when I engaged the cruise control it would disengage randomly at any speed at any given moment and the same issues occurs that for a split second the speedometer would drop and go back to the speed I’m traveling….

My only guess is a sensor like the VSS (vehicle speed sensor) is failing or become faulty but it’s anybodys guess. Would it pop a code if taken into a reputable shop? What else could it be?

Thanks.
-Sam

FullForceRam · Mar 15, 2022

Anybody? I cant imagine I'm the only one having this issue..

jws123 · Mar 15, 2022

FullForceRam said:
Anybody? I cant imagine I'm the only one having this issue..

Not very common to have issues with the speedo could be a gauge cluster issue. Best thing to do is have someone with a good scanner see if they can pull any codes not your cheap $50 one or autozone.

crash68 · Mar 16, 2022

There isn't a single sensor used for the speedometer, the speed is calculated from all four wheels via the ABS wheel speed sensors.

csuder99 · Mar 16, 2022

Adding to crash68's post, that also means the speed information is sent from the ABS module via the CAN bus. Sounds like both the cluster and the PCM briefly either don't receive speed information or receive implausible data, and the PCM disengages cruise control because of it.

The problem needs either alfaOBD or a shop level diag tool to query various modules for error codes.

Dudro612 · Mar 16, 2022

Could be an error with a wheel speed sensor.. they go out pretty regularly.

Daw14 · Mar 16, 2022

I wonder if the brake switch may be involved ?

FullForceRam · Mar 17, 2022

jws123 said:
Not very common to have issues with the speedo could be a gauge cluster issue. Best thing to do is have someone with a good scanner see if they can pull any codes not your cheap $50 one or autozone.

jws123 said:
I figured as much. I've got an appointment to take it into my service tech shop on Monday to see if they can pull any codes.

FullForceRam · Mar 21, 2022

For anyone else having these issues, my technicians called me up and everything they are pulling from the scanner are having some type of issues indicating that there might be something goin on with the battery, or battery related...
It's always started up just fine and I've never once had to jump it in the time I've owned it (almost 2 years) but I could see how a battery could cause some issues.

They are going to keep it overnight and see if it pulls any other codes tomorrow AM as they continue to diagnose. If all else fails I'll replace the battery and see how it goes from there.

FullForceRam · Apr 9, 2024

I forgot to reply back on this topic so my apologies to anyone having this issue..

It ended up being a FAULTY Belt tensioner and belt that was causing the issue. Somehow the tensioner was going back and didn't have the correct tension this the belt was glazing over the pulleys and "slip" which then sent a malfunction to the cluster displaying the RPM/MPH...

Weird I know, but right after replacing the belt and tensioner it ALL went away..

Vehicle speed sensor going bad?

FullForceRam

Senior Member

FullForceRam

Senior Member

jws123

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crash68

ACME product engineer

csuder99

Senior Member

Dudro612

Junior Member

Daw14

Senior Member

FullForceRam

Senior Member

FullForceRam

Senior Member

FullForceRam

Senior Member

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