High Coolant Temp. Code 14

jhid101968

Hi Everyone, I have a 1991 S-10 4.3 L 5 speed. I have a 14 code (high temp.) 2 years ago I replaced most of the sensors on the truck including the temp sensor (intake manifold one). Last week the check engine light came on and it's code 14. So I replace the temp. sensor again. But that didn't help. I've check the wiring connection and drained the coolant and replaced with fresh. Still nothing. The check engine light stays on 80% (on and off, mostly ON) of the trip to work in the morning. Then stays off 80% ( on and off, mostly OFF) of the trip home in the afternoon. Any ideas of what the problem is? Thanks! Kevin

rickdon

Did you replace the thermostat? If not, get an OE replacement.

thecardoc3

Code 14 means that the coolant temperature sensor circuit voltage is too low (it doesn't necessarily mean that the sensor is bad). Since the engine control module outputs that voltage to the sensor the first thought is that either something is wrong causing the module to be unable to provide the refence voltage OR the yellow wire between the sensor and the computer is going to ground.

A severe overheat can also cause a code 14, but we are talking about getting the voltage to go below about .25v which is almost 280f.

When this is acting up one of the first things to do is measure at the yellow wire. "NORMAL" voltage range would be around 4v very cold (-15f) to around .8v and normal engine temperature (210f). Again with this experiencing a problem you will see a voltage less than .3v. While you are measuring the sensor circuit, unplug the sensor and now see what the voltage goes to. It should approach 5v open circuit. If the voltage doesn't increase with the sensor unplugged you are seeing the problem exactly like the computer is. Now you need to start working back towards the computer to find out what the exact cause is.