Does anyone know if a faulty engine computer/ECM have anything to do with speedometer not working? Did some research on it and someone suggested it might be the problem, but from what i found, all functions are mainly for the motor.

 

What year Explorer are you referring to?

Does the ABS work properly?

Does the odometer still count up the miles?

Does the Cruise Control still work?

-Rod

 

Cruise control stopped working a long time ago, odometer does not count the miles, speed and rpm gauges don't work, but all others do.

 

I'm still not sure what model year you are referring to, but since the tachometer doesn't work either, I'd be inclined to say the issue is probably the instrument cluster and possibly the speed sensor/ABS sensor rather than the PCM.

Depending on the model year, and if you have a scan tool, you could access the vehicle speed parameter via the scan tool to determine if the PCM is getting and interpreting a good vehicle speed signal.

-Rod

 

Sorry, forgot to specify.
2005 Ford Explorer Sport Trac Adrenalin. I changed the speed sensor already and it's not it. I did use a scanner to check on rpms and speed and seems to work. Narrowing down to cluster. I was finally ready to buy a new one but someone told me about the computer so that's why I'm holding off

 

There is a microprocessor that is part of the instrument cluster, maybe that's what the person was thinking of. Before swapping out instrument clusters, confirm the fuses for it are good. Specifically you're interested in fuses F2.25 (7.5A), F2.14 (7.5A), F2.27 (7.5A) and F2.26 (10A), all in the Central Junction Box. F2.26 also provides power to the Battery Saver Relay so I suspect other items would be having issues if this fuse were bad.

The speedometer and tachometer signals are both sourced from the PCM so since the PCM is reading good for both on the scan tool I would not expect the issue to be the PCM.

-Rod