temp sensor, and vss - Ranger-Forums - The Ultimate Ford Ranger Resource


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Old 10-28-2007
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temp sensor, and vss

so, let me get this straight. The vss is hooked up to the temp sensor for the ohc so that when you are stopped for what ever reason the temp sensor doesn't get all funky when it starts to read higher temps, from the engine bay and what not.

what is the upper threshold of the temp sensor? Would it happen to be 140 deg F/ 60 deg C?

the reason i ask is this. last Sunday on my drive home from the football game in Buffalo i look up to see my OHC reading 140 deg, when in fact it was maybe 70- 80 deg (crazy weather for mid October in wny). the whole ride home after that with out me stopping it still read like it was pegged at 140. it may have dropped to 138 once or so, but that is it. the next day, and days after that i start it up after it has been off for the night, or while i am at work and it reads closer to what it really is. but on the way home it steadily rises (ex i live 6 mi from work, in that time the temp will go from low 50's to the low 80's)

I have the sensor mounted between the grill and the radiator with soldered and heat shrunk connections.
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Old 10-28-2007
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Factors Affecting Accuracy - OHC Temperature Display

The temperature display operates through the use of a thermometer sensor (15A022) mounted behind the front bumper/grille. The display can be changed from English to metric units.

The data from the temperature sensor must be processed and adjusted so that engine heat does not affect the displayed temperature. When the ignition is first turned on, the module checks to see if the ignition has been off for more than two hours. If it has, the currently sensed temperature is displayed. If the ignition has not been off for two hours and the sensed temperature is higher than it was when the vehicle was turned off, the old temperature will be displayed. If the ignition has not been off for two hours and the sensed temperature is lower than it was when the vehicle was turned off, the currently sensed temperature is displayed. To update the temperature, the module looks at several different factors, as listed below.

Engine Cold

- If ignition has been on for less than five minutes, and was previously off for longer than two hours, the engine is cold and does not affect the temperature sensor. Therefore, the current sensor data is used.

Engine Warm, Updated Temperature Cooler

- If ignition has been on for longer than five minutes or if the ignition was off for less than two hours, the engine compartment may be warm from the heat of the engine. The current sensor data is used only if it is less than the stored temperature reading from before.

Engine Warm, Updated Temperature Warmer

- If the sensor data indicates a higher temperature, the module looks at the vehicle speed to determine whether engine heat is causing erroneous readings. A "high speed counter" is used to determine this. The counter is incremented when the speed is greater than 53 km/h (33 mph) and decremented when the speed is between 16-53 km/h (10-33 mph). If the speed is less than 16 km/h (10 mph), the counter is reset, and the displayed temperature is not updated from its last reading. If the counter is greater than two minutes, the currently sensed temperature is displayed. If the high-speed counter has counted less than two minutes, the temperature is allowed to increase only one degree per minute.

- If the temperature sensor is short- or open-circuited, the display will read SC or OC, respectively, instead of a temperature. If the temperature drops below 3.3C (38F) or is below 3.3 C (38F) upon power-up, the display will alternate between displaying "ICE" and the temperature. The display will alternate every two seconds for a time of one minute.
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Old 10-28-2007
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so it isnt sorted, or open circuited, so i can assume that the temp sensor is bad.
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Old 10-27-2008
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Ok im thread digging here but my temp reads SC all the time so is my sensor bad? or is there a way to fix this.
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Old 10-27-2008
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If you unplug the sensor does it change the reading?
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Old 10-27-2008
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funny you should bring this up, i just picked up a different sensor, one from the same year as my ohc. (when i bought the ohc from somone they didnt send the temp sensor) i have plans to fix it sometime this week.
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Old 10-27-2008
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Quote:
Originally Posted by Shaklakan View Post
Ok im thread digging here but my temp reads SC all the time so is my sensor bad?
As noted above, "SC" indicates that there is a short somewhere in the circuit. Which means it could also be a wiring or harness connector issue.
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Old 10-27-2008
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Ill check it out.
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Old 10-27-2008
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Ok so the wires running by my parking brake were to close and the got rubbed down and exposed to the metal so it was a short over there and i replaced the wires and everything is working like it should be guys thanks!
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