Tach works off and on

[Clusterpup]

My tach is going crazy. Sometimes it works, other times it doesnt and sometimes it displays lower engine speed then what the engine is really running at. Anyone have any ideas where to start looking. I think it may have started acting that way after I submerged the truck pretty deep in mud. Crank position sensor maybe? Can it get dirty and start acting up?

 

[bdmaash]

My tach is going crazy. Sometimes it works, other times it doesnt and sometimes it displays lower engine speed then what the engine is really running at. Anyone have any ideas where to start looking. I think it may have started acting that way after I submerged the truck pretty deep in mud. Crank position sensor maybe? Can it get dirty and start acting up?

the tach voltage comes from the PCM, so unless the truck also misfires the CPS is not the problem, it will be a connector from the PCM to the cluster, there's probably 3 connectors to check - the PCM, cluster, and an intermediate one, and it could also be a grounding issue.

 

[Clusterpup]

Alright, thanks. I have to check out the connections then. I guess I'll start with the cluster.

 

[Jarred767]

I have pretty much this exact same issue on my '98. It was like it when I bought it a few months ago and hasn't gotten worse or better, but it doesn't seem to be affecting the engine at all. More of an annoyance. Sometimes it works fine, but most times it sits at dead zero and will randomly "pop" to where it's supposed to be, then goes back to zero. I've just lived with it so far, cause I've got bigger things to worry about on this truck, but if it's a relatively easy fix...

OP (or anyone else since this is an old thread), did you (or anyone else) get this resolved, and if so what was causing it/what needed to be fixed/cleaned/replaced?

 

[01STrunner]

Sounds kinda like a bad ground.

 

[daChurchPcGuy]

If it's just the tach it sounds like bad solder joints on the circuit board. The fix requires pulling the cluster and resoldering the pins behind the tach. Here's a thread explaining the issue:

http://www.justanswer.com/ford/7jbwu-explorer-sport-trac-4wd-2001-explorer-sport-trac.html

 

[Jarred767]

Thanks for the help, I probably would have never found that link. I've bookmarked it so I can come back to it once I get some more pressing issues taken care of. Thanks again!

 

[just1me]

I have the same problem, I just haven't taken it apart yet to check it out. I seen that link though before when researching on google the issue.

 

[daChurchPcGuy]

If you pull your cluster to re-solder the tach connections you might as well re-solder them all. It's either a design issue or maybe our gauges were made on a Friday.

 

[just1me]

It seems like an occurring issue since I have read about it happening with other explorers, and rangers as well.