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Throttle position sensor[850/1995] posted by Stefan on
Monday, 14 May 2001, at 4:35 a.m.
I'm getting the code 2-4-3, "Throttle position sensor signal outside voltage range" on my 850. The lambda warning light comes on, and I have cleared the code a couple of times only to find out that it returns after a couple of days.
Yesterday I removed the top cover to the throttle body and (I think) located the sensor and cables. I cleaned the connector with some WD-40 and plugged it in and out a couple of times. Cleared the code, and thought that was it... Wrong! It came back this morning! :(
I'm not sure what to do. Is it just the sensor, or is it the cables? What does "outside voltage range" mean? Voltage too high? Too low? Bad sensor? I'm clueless. I'd rather not just change the sensor to find out it is the cables or something else!
Would be grateful for any advice.
Stefan
--Stefan - 1995 850 SE, B5252S, manual transmission, 75K miles.
Re: Throttle position sensor[850/1995] posted by joe on
Monday, 14 May 2001, at 9:18 a.m.
The throttle position sensor (TPS) is a rheostat. It is supplied w/ a voltage that the computer uses as a reference. As the throttle is opened, the rheostat causes the electrical resistance to change, which in turn causes the voltage to change (remember Ohm's Law: V=IR, where I equals current). So, the computer continuously gets a changing voltage which it uses to determine the position of the throttle. However, the computer knows the lowest and highest voltages should be, so if the returned voltage is out of range it throws a code. I think you need to replace your TPS. You can verify this by back-probing with a digital VOM and checking the voltage at idle and the wide open positions (key on, engine not running) and comparing those readings to the specs. Also (don't need the specs for this) you can check that the resistance changes smoothly as the throttle is opened (key off). In my experience, when the TPS goes out, there will not be a smooth change in resistance as the throttle is opened - it will suddenly change.
Re: Throttle position sensor[850/1995] posted by Brandt on
Monday, 14 May 2001, at 1:27 p.m.
The TPS on my ’95 850 failed at about 50k miles. The failure mode manifested as sporadic shifting at constant freeway speeds and loads. Removal and probing with a DVM indicated a discontinuous voltage (resistance) reading that got worse with temperature soak. Replacement solved the problem. Interestingly there were NO OBDII codes. The resistance readings were always within spec; the computer was interpreting the faulty readings as an erratic right foot and tried to compensate as best it could.
Kind of reminded me of HAL in 2001…
T-Gul and Silver S60T5M