93 f 150 , 300 six , temp sender unit erratic , have mechanical gauge to replace but was wondering if the stock sending unit has anything to do with the computer operation and / or is there a way to have both operating , thanks for any info

 

These motors use 2 seperate temp sensors, 1 for the computer and 1 for the dash. The dash sensor is a little round thing about the size of a dime with a single stud sticking out the top where the wire attaches, dirt or corrosion here make for an erratic gauge, the sensor could be going bad as well. I have no idea where this sensor is on the I6, on the V8s it is in one of the intake water passages, I suspect it's probably in the block on the 300 as the intake has no coolant passages.

 

From what I understand, the sensor for the temp gauge only has two states,..On and Off.

The gauge in the dash is a normal gauge, but has a resistor wired in series with it which is mounted on the dash circuit board.

I believe variable sensors to match this gauge are available, but I don't know exactly which one.

There was a thread here about a year ago which discussed this issue including the need to jump that resistor when switching to a variable sensor.

 

to begin i had no dash gauge function and was getting a check engine light , found the sensor down on the passenger side of the block and found the lead off , plugged in and now have some function to the gauge but kind of moves around but now i don't get the check engine light , made me wonder if it interacts with the computer or if the computer is just telling me it's not functioning. the engine is running at normal temps and its not a cooling issue and i'd rather have a manual gauge. sounds like a plumbing project to hook up both , thanks for the info

 

The CE light is a coincidence, you should pull the codes and see what the problem is.. see Ford Fuel Injection.

 

Almost.. that is the oil pressure switch.. not the temp sensor.

 

While you were posting the above, I was editing mine,..............A search of past threads might be helpful for you.

 

He He................

Darn criss crossed posts.

Conanski, does this mean that the old temp gauge can not be used ??

 

The stock temp gauge should work fine if the sensor is in good shape and the wire is firmly attached. An secondary temp gauge can be added by placing another sensor anywhere in the coolant system, so you don't need to disable the dash gauge.

You can convert the stock oil pressure gauge to an actual gauge(not just a fancy idiot light), by installing an oil pressure sensor in place of the oil pressure switch, and altering the gauge cluster to short the resistor for this gauge.

 

The temperature gauge is variable. It is the oil pressure gauge that is an on/off switch on most of these trucks.

 

thanks guys , think I'll put in a new sending unit first , see if it clears up the erratic stuff .

Thanks again !

 

i haven't done it with my temp gauge (yet) but i installed a mechanical oil pressure gauge and also wanted my original one to still work. so i just got a t-fitting, removed the stock sensor, stuck the t-fitting in the block. then stuck the original sensor in one end and the mechanical gauge fitting in the other end. the original gauge reads right where it did before and the mechanical one reads right where haynes repair manuals tells me it should.