1998 int 9100 wont go over 1500rpm speedo no read until 50mph help

Probably I would try new era like you're saying just see if u can find a good test part first so your not spending all that money for nothing

 

Did both gauges start having issues at the same time?

 

Where I am coming from is a Pete with an N14. It would not exceed 1700? RPM intell it reached a speed that is only available in high gear (computer programmed). Tightening the transmission yoke nut fixed the problem of the pickup wheel spinning on the yoke. The dirty signal would do the same thing. You have a lot in this already. Try a 1" impact with a 2 3/4 socket on the out put yoke.

 

I have a 2000 Pete N14 18spd, mine has 2 sensors on the back of the trans. one for ECM and the other for speedo.
You can also use insite to change the RPM derate for no signal from speedo.

 

How are you checking the wiring? Just a visual check of the entire harness or are you actually physically inspecting the individual wires? Checking pin to pin with an ohm meter usually does the trick. Checking across pins also works to determine if you've got shorts inside the harness. Just gotta make sure you have both ends disconnected when doing that or you can pick up strange ohm readings sometimes.

 

I thought mine only had one, changed it and still no speedo, the second sensor is hard to see it is at the 12:00 position.
My RPMs were also screwy until both sensors were replaced

 

Before you attempt replacing an ECM, at least try a test ECM if you can borrow one. If not, I recommend just running new wires from the sensor to the ECM and retest.