With the engine cold, that 1-wire sender for the temperature guage will have a larger resistance to ground. Your friend will understand what that means. I don't understand what he means by "a very weak signal". He'll measure resistance between that 1 pin vs. ground and we need a table of resistance vs/ temperature from a shop manual.

 

ah ok well i just replaced the sender unit and the temp gauge is working again. reconnected a wire that had broken goin to the radiator fan, and the fan is working again. now the only issues im having is the speedometer, and engine redlining at 5500 rpm

 

Speedometer not working at all? Does the cruise-control work? Does the odometer count up even though the speedometer doesn't work?

If all 3 things are out, along with a CEL (code 17) then it's either your VSS (on the trans) or a bad connection in the wires leading to the VSS.

 

um odometer doesnt work, cruise control works, speedometer jumps to 20 when i key on or start the car, and wobbles when im slowing down to a stop or just barely going. like 2-3 mph it moves up and down between 20-25

 

Cruise control NEEDS the VSS, so that means the VSS and the wiring is OK at least as far as the ECM and cruise module are concerned. Seems pretty likely a bad gauge in the cluster?

 

thats what ive been told. though it happened when i was changing the axle on the passenger side, so i thought it might have something to do with that. any idea why my car is redlining at 5500 rpm?

 

Not sure about that. If the ECM isn't getting a VSS signal, it might set a lower redline. But then again, if it wasn't getting a VSS signal it would set a check-engine light.

Is your check-engine light working? Does it light up for 2 seconds when you first turn on the key, then go out (bulb-check)?

 

yep it comes on when i start the car, but it never comes on while im driving

 

Im having this exact problem with my 99 Civic. I replaced the sender unit and the 2 wire unit with no luck, gauge is still faulty.
The only thing I have left to replace is the sensor on the thermostat housing, could that have anything to do with it??

Also im driving 1400 miles to California in 3 days. JUST IN CASE this issue doesnt get fixed, could anything bad happen by having the fans constantly running? The car has no issues with over heating but Id rather not risk it.

 

Mine did this on my Civic last year. I replaced the harness and it fixed everything. I dont recommend this, but if you cant find another solution then it could fix it.