i have a 93 4.0l yj and my coolant temp gauge is not working now i've replaced the coolant temp sensor. but still the gauge is not moving. so i looked at my ondemand schematics and found that
from ecu to coolant sensor is a tan/black wire. the second wire on the coolant senosr is a black/light blue wire that is a sensor ground from the ecu.
for the temp gauge it says there is a vilot/yellow wire that goes from the gauge staight to the coolant temp sensor but that is not the cast.
so where does the violet/yellow (sending wire) for the coolant temp gauge come from?

thanks
lee

Howdy DR There should be 2 temp sensors on that engine... ONE of them tells the ecu when the temp is high enough to switch to a LEAN condition..
The OTHER one tells the gauge what the temp is.. Make sure to get the proper one when changing them out..
Changing the ecu one will NOT change the temp on the gauge.
Big JIm <img src="/forums/images/graemlins/pfft.gif" alt="" />

thanks for the reply i double checked the wiring harness. it looks like at the rear of the engine on the manifold side there is a wire not pluged in (vilot/yellow) now I looked for the sensor but on my cylinder head. it is bare where i think a sensor could be taped into it. By the looks of it the engine has been replaced. now what year engine do i have? and what could i do.
thanks again
lee