Coolant Temp Switch

[bwc]

Good Morning: What is the best tool to remove this switch? The upper rad hose cast tube(gooseneck) is in the way of a socket and the best I can come up with is a 7/8" crowsfoot socket? This switch by the way is located on the passenger side front area down by the pump. Surely you do not have to remove upper rad hose etc to get at it. Thanks.

Brian

 

[argve]

I know the switch and it will be a pain in the tailpipe to get it out without removing the upper water neck. Now I have to ask are you sure it's bad because it's typically a pretty bullet proof item, typically when the fast idle and timing advance quits working it's either it's not making contact at the plug or the wiring has gone bad. Not saying you haven't troubleshot it fully but just mentioning it because of what I have seen.

 

[icanfixall]

Why are you trying to replace this switch? It has nothing to do with the dash gage. It only sets the fast idle and pump advance til the coolant reaches 120 deg, then everything goes back to normal idle and normal advance.

 

[bwc]

Gentlemen: Thanks.All good questions. Four years ago my truck would not start, no way, no how. Found out that the wiring harness plug on pass side inner fender had a frayed, rotten wire which supplied power to fuel shut off solenoid. When I replaced this wire I installed a 10 amp in line fuse. Two weeks ago my truck died while out camping. Left me stranded. I noticed right away that the 10amp fuse had blown. Put in another fuse. It blew. After getting the truck home I started checking the connections in and around the pump. If I disconnected the temp switch the truck would start right up, fuse good. If I connected to the switch again, fuse blew, no start. I noted some corrosion on the temp switch plug and cleaned it. The fss is getting power when key is on like it should. The temp switch is getting power when key is on, and the fast idle solenoid is also getting power from the temp switch when it is attached. I connected all three and the truck started. Fast idle worked and came down to normal idle after reaching 122*F just like it should. It may have been the connector who knows. Can anyone tell me what the normal resistance of the temp switch is new so I can check my oem? Would probably save me some work. Does the temp switch either work or not work and do they short themselves out or was the fuse blowing due to bad connection? I put the inline fuse in because it was easy to do and it would help me at a glance to see if I was getting power instead of taking out a test light and fumbling around in the dark. Thanks again.

Brian

 

[Mr_Roboto]

It's an on/off switch, so resistance should be around zero cold and infinite (open) hot.

You can check between each terminal and ground, if you show any continuity to ground then the switch may be shorted to ground internally.

I believe it would be more likely that there was a shorted wire rather than a switch shorted to ground.

 

[krawlr]

I need to get one of these switches for my junk. (a terminal is broken off) Anybody have the correct part# and best place to get one?

 

[h2odrx]

mine did the samething, $52 from ford #E8TZ-9E939-A

 

[bwc]

Checked the switch with my VOM. Shows 10 ohms or so when cold. New switch is O. I will replace the switch when I do a coolant re and re and new t'stat. Thanks again for the help.

Brian