Hello, I hope this is the correct forum for this quesiton my apologies in advance if it is not. I have a 2003 Ranger Edge edition. The tach has started kind of bouncing. It'll show 4000 RPM at hwy speeds and then just fall to 0. I have a 5 speed and everything feels and sounds normal and the engine is not revving up. Do you think that my gauge is going bad or something else. How could I troubleshoot. I am not very mechanically inclined. Thanks.

 

So TWO issues not one?

Engine won't REV
And tach is not reliable

As for the tach it could be the tach itself or the wiring for it
Tach signal comes from the computer(PCM) in engine bay, pin 48 a tan/yellow wire
This wire runs to the larger multi-wire connector that passes wires from engine bay into the cab, so another connection there
Then the same color tan/yellow wire on the cab side of that connector runs to the back of the instrument cluster, pin 15 on connector "A"

So there are 3 connections, PCM, firewall, cluster, for this signal
You could pull the cluster
Pull the connector on PCM
then test continuity on the tan/yellow wire, move wires at firewall connector around while testing
"Continuity" tests if both ends of a wire are connected, in this case the tan/yellow wire at PCM and cluster have a good connection so wire is OK

If it is then replace cluster, or if you can find just the tach section replace it
1996 to 2003 Rangers or Mazda B-series used the same clusters so any of those would be plug and play
There were two different clusters, with Tach and without Tach
Also two different colors, black face and white face
Always replace the 6 back light bulbs when a cluster is out, they are cheap and a pain to replace when one burns out, lol

 

Awesome. Thanks for the info. Sorry for the confusion. The engine will rev fine. I just meant when the tack is showing high rpm the engine sounds normal not like it is running at 4000 rpm.