Car Fix DIY Videos

Video tutorial on how to troubleshoot and replace the exterior ambient temperature sensor on a third-generation Dodge Ram. Here I’m working with a 2006 model and a similar procedure may apply to other #Mopar vehicles as well. Over time these sensors will start showing irregular temperatures or may not even work at all. If the circuit or data is faulty, you’ll be left with two dashes on the digital readout in the cabin. In this scenario, the module could have failed. The sensor circuit can also max out on temperature values, the most it’ll read is 55C or 130F. It’ll show the same value if there is a short in the circuit too. The lowest temperature it’ll register is -40C or -40F. If the sensor failed with an open circuit or is missing, it’ll also produce this same value. #dodgeram

#OEMTOOLS Heat Gun: https://www.mobiledistributorsupply.com/24498-oemtools-24498-dual-temp-heat-gun-oem

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Tools/Supplies Needed:
-new sensor
-multimeter
-replacement clip
-heat gun
-thermometer
-10mm wrench

Procedure:
Disconnect the negative battery cable is only needed, this requires a 10mm wrench. The sensor is located behind the grill on the radiator support. The clip for mine seems to have disappeared and this seems to be a fairly common problem, so you may find yours hanging around this area. You may be required to remove the clip which holds the sensor in place.

To disconnect the electrical connector, press down the tang and then pull off the plug.

Testing the plug, reconnect the battery first, you’ll need power at the plug. Turn the key in the run position to activate the sensor circuit.

Here’s a quick view of the temperature readout, with the sensor disconnected, here you can see it’s at the lowest temperature value it’ll register.

Using a multimeter, set it to the DC 20v max. Using your probes, test the plug. We should have about 5 volts here, being 5.57v, this is fine. If the value is excessively high, you may have a voltage short going back to the module. If the voltage is excessively low or there’s no value at all, there may be damage or correction present in the plug, wiring, or back at the module.

Another process of elimination is strictly testing the signal source at the plug. Looking at the plug, with the connector clip at the top, this would be the terminal on the left. With the meter on the same setting, touch one probe on the signal terminal and the other on a good ground source on the truck. Here I’m using a bolt behind the bumper.

Based on the previous test, if a value is ONLY present here or is improved, then there’s an issue with the opposite wire, this would be at the plug, wiring, or at the module.

The problems can be further isolated by removing the module, then testing the wires between the sensor plug and module plug, however, I won’t be getting into that in this video.

As for testing the sensor, you can measure the resistance and there will be specific values based on the temperature it’s exposed to. I do have a thermometer here as a reference. Currently, it’s about 26C or 79F.

Set the multimeter to the 20k resistance setting.

Touch the probes on the terminals inside the sensor. We are looking at about 9.45 kilohms.

A heat gun can be used to test the temperature at 55C or 130F. Setting it on the lowest setting, you’ll need a bit of distance so the sensor isn’t overheated. Monitor the thermometer and it should stay warm for a bit. Then using the multimeter test the resistance. At 55C or 130F, the resistance should be 2.488 kilohms. Look for a value close to this as it may be tough getting the exact temperature, as you can see this sensor is well out of range, therefore a replacement is required.

The sensor can also be tested at -40C or -40F, you may need a can of air for this as it has nitrogen. The value at this temperature should be 336 kilohms.

Disconnect the battery again and install the new sensor. Ensure the plug is properly seated, you’ll know it’s connected when it’s followed by a click.

As for putting the sensor back in place, I used a fir tree-style clip and installed it in the lower hold with the sensor portion facing up, the plug portion on the bottom. Reconnect the battery and verify the sensor is working correctly.

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