Possible OHC temp sensor problem - Ranger-Forums - The Ultimate Ford Ranger Resource


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  #1  
Old 05-22-2006
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Possible OHC temp sensor problem

How do you know if you're temp sensor for the OHC mod is f***** up......


Mine reads the same 9 degree celcius all day here...and it's been over 20 today!

Originally it worked fine for the first day or so.

Its mounted on the horizontal bar in front of the rad just below the grille.

Just used some zip ties and it's secure.

Would the location be the problem, or is the sensor need to be replaced?

Is it missing a part? Wrong one? If it's the wrong type, someone have the right Ford part #?

How can I test/re-set it?

Would it have to be calibated like the compass?

Seems it did this mostly after the compass calibration, but I'm no technical wizard...so I have no clue.

Last edited by aftermarket; 05-22-2006 at 07:41 PM.
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Old 05-22-2006
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Oh, mine looks like the top one....




Maybe its the wrong sensor?



Last edited by aftermarket; 05-22-2006 at 07:45 PM.
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Old 05-22-2006
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Try this

Go find an abandoned parking lot and follow the following steps:

Press and hold the "MODE" button until you see "VAR" (takes around 5 seconds)

Release the "MODE" button. Push the "MODE" button until you have selected the zone you are currently in.

Release the "MODE" button and wait until the console is back at normal operation.

Press and hold the "MODE" button until you see "CAL" (takes around 9 seconds)

Release the "MODE" button.

Now the fun part. People will think you are crazy. Drive in a circle at around 3mph. Your console will be changing direction really fast. Continue to do this until the console is back at normal operations.


I found it here
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Old 05-22-2006
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Yeah, I did that already.


Compass works fine, temperature does not.
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Old 05-22-2006
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Those two sensors in the picture above are both overhead console sensors from different years (Blue/White and Blue/Yellow wires). However, there is also an EATC ambient temp sensor (Red/Orange and Pink/Black wires) that looks the same but is different internally.

Using the EATC sensor as the temp input to an overhead console will give erroneous readings. I have heard that the EATC sensor has about 30,000 ohms impedance at 20C (68F) and the console sensor is around 10,000 ohms at the same temp.

Another thought. Do you have the speed sensor input (gray/black) hooked up? Without it, the console can hang on a low morning temperature reading and refuse to update.
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Old 05-22-2006
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Quote:
Originally Posted by rwenzing
Those two sensors in the picture above are both overhead console sensors from different years (Blue/White and Blue/Yellow wires). However, there is also an EATC ambient temp sensor (Red/Orange and Pink/Black wires) that looks the same but is different internally.
Do you have a proper part # that could be printed on the sensor? Sounds possible.

Quote:
Originally Posted by rwenzing
Another thought. Do you have the speed sensor input (gray/black) hooked up? Without it, the console can hang on a low morning temperature reading and refuse to update.

I will go check. Be back later to update you.
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Old 05-22-2006
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The number embossed on the sensor is probably the "engineering part number" which is not the same one used in the Ford parts system. Why Ford creates this confusion is beyond my understanding.


Did you check the sensor connector color codes I gave you in my post above? Assuming that the sensor was obtained from the donor Explorer together with its matching connector, that should help you identify which sensor you have.
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Old 05-22-2006
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The most likely reason is a bad VSS connection or failure to hook up the VSS. That is the symptom: in warmer weather in particular the OHC does not update. It's attempting to NOT read engine heat by not taking new readings when the truck isn't moving. Without the VSS signal, it can't tell when the truck is moving.

Fix or connect your VSS signal and all will be well. Everytime this is reported, this has been the problem.

The key is it worked fine for a day or so -- but it was cooler those days. The motion algorithm appears to only kick in when the temperature rises above a certain point.
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Old 05-22-2006
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Quote:
Originally Posted by buzzair

Release the "MODE" button. Push the "MODE" button until you have selected the zone you are currently in.

I found it here
I don't mean to highjack this thread...but what do I have to select the right "zone" for my OHC? What zone is NJ?

I emailed that dude who did the write up, but no response.
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  #10  
Old 05-23-2006
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Quote:
Originally Posted by rwenzing

Did you check the sensor connector color codes I gave you in my post above? Assuming that the sensor was obtained from the donor Explorer together with its matching connector, that should help you identify which sensor you have.

Going to check it tonight. Last night got messed up with yard work..lol..
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Old 05-23-2006
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The thing is here: didn't he say it worked correctly for awhile? With the wrong sensor, that would never have happened. Their resistance ranges are different by about a factor of 3 and the EATC sensor would never work correctly.

You're chasing your tail with the sensor, if it ever worked. A bad sensor would NOT cause it to "freeze" the reading -- the only thing that causes that is the VSS alogorithm to keep from seeing engine heat too much while stopped on warm days.

This was discussed over and over on GenEdge and elsewhere -- including here at one point or another: frozen readings are from the VSS connection being bad or not having been made in the first place.

You've never said if you even hooked it up? There are times I don't know why I even bother to post...
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Old 05-23-2006
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Quote:
Originally Posted by buzzair
I don't mean to highjack this thread...but what do I have to select the right "zone" for my OHC? What zone is NJ?

I emailed that dude who did the write up, but no response.

The zone setting can be found here CLICK

Download the 1998 Explorer manual. There is a small map of the US with the zones shown.

NJ should bee either 10 or 11
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Old 05-23-2006
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Quote:
Originally Posted by n3elz
The thing is here: didn't he say it worked correctly for awhile? With the wrong sensor, that would never have happened. Their resistance ranges are different by about a factor of 3 and the EATC sensor would never work correctly.
John, this was a very recent installation so I doubt that it has ever worked correctly. I just found out that he has the console VSS input tapped to a different gray/XXXX wire at the SJB. As soon as he moves it to the gray/black, I trust that all will be good.
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  #14  
Old 05-23-2006
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Quote:
Originally Posted by Cape Fear
The zone setting can be found here CLICK

Download the 1998 Explorer manual. There is a small map of the US with the zones shown.

NJ should bee either 10 or 11
Cool thanks, I downloaded it and took a screen shot of the map. I'm pretty sure im in Zone 10. The map isn't the greatest.


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  #15  
Old 05-23-2006
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When my temp sensor wire came loose, my OHC read 188, which is every bar on the digital display illuminated. An INCORRECT temperature will be a problem with the VSS hookup, as John stated. I must have a loose connection, because mine occasionally refuses to update, but I'm too busy/lazy to take the dash apart to trace it.
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  #16  
Old 05-23-2006
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mine has never worked right and i have twice pulled the dash apart to redo the wire to the VSS and the second time i ran a whole new wire and it still doesnt work it will reset after a few hours but it will stay on the temp when the truck was started
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  #17  
Old 05-23-2006
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Quote:
Originally Posted by rwenzing
Those two sensors in the picture above are both overhead console sensors from different years (Blue/White and Blue/Yellow wires).

Yep that's the one I have. So must be the speed control wires....
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  #18  
Old 05-24-2006
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Sorry for the expression of frustration -- no one even acknowledged my point. Frustating when you've installed like 10 of these things and troubleshot many more and it seems like no ones listening. Just a brief excessive pride glitch, lol -- forgive me.
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Old 05-24-2006
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Quote:
Originally Posted by n3elz
Sorry for the expression of frustration -- no one even acknowledged my point.
Consider it acknowledged. I tried to make that same point in post #5 above after answering the OP's original question. The only reason I know about the VSS issue is because I read about it in your posts and in your how-to.
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  #20  
Old 06-01-2006
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Ok Bob and John, this isn't to frustrate you guys anymore BUT!...

I have installed the OHC as per your cardomain instructions and it's great! I'm sure that i'm in the right time zone, positive that my connections are correct with both the temp sensor and the VSS. The temp. updates itself and seems to be "somewhat" accurate. The somewhat means that when comparing the reading to many thermometers, it seems to be about 4, possibly 5 degrees higher. The only thing that I can think of is that when I bought the OHC and the sensor, they came out of 2 different explorers, but same years. Any ideas guys?
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  #21  
Old 06-01-2006
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It shouldn't matter that the components came from 2 different Ex's. You can bet that Ford doesn't match components to each other on the assembly line - each has an allowable tolerance. You can get "tolerance stack up" that can multiply the error but 4~5 degrees seems to me like a bit more than you would expect.

Check the location that you are using for the sensor. Be sure that it is not too close to the radiator where it can pick up radiant heat or get into an air eddy circulation. Mine is on the front of the radiator bulkhead but way over to the side below the headlight. In this location, It is protected by the bumper and should be far enough from the radiator.
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  #22  
Old 06-01-2006
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Another quick and possibly dumb question...if my OHC doesn't turn off when I turn my truck off, that means I have the dimmer wire hooked up wrong. Correct?
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Old 06-01-2006
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Quote:
Originally Posted by buzzair
Another quick and possibly dumb question...if my OHC doesn't turn off when I turn my truck off, that means I have the dimmer wire hooked up wrong. Correct?
It probably means that you have the gray/yellow console power wire connected to constant power. It should be tapped into the yellow/black at the radio harness connector which has power in RUN/ACC only.
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