How to check sensor temperatures with a multimeter
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2nd Gear
Joined: Sep 2019
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From: Tucson
How to check sensor temperatures with a multimeter
2012 Road King. DTC-P0118. EDM Says to check for shifted sensor resistance value bycomparing temperatures of ET and IAT sensors with engine at room temperature. "Sensor Temperatures should be within 10 degrees of each other." How do I check sensor temperatures with a multimeter? I have done all the other resistance and voltage tests listed in the EDM.
2012 Road King. DTC-P0118. EDM Says to check for shifted sensor resistance value bycomparing temperatures of ET and IAT sensors with engine at room temperature. "Sensor Temperatures should be within 10 degrees of each other." How do I check sensor temperatures with a multimeter? I have done all the other resistance and voltage tests listed in the EDM.
If you do not have a scan tool, there may be a resistance value chart for the sensors in the EDM - I do not recall on that book.
Anyway - that code is for an open circuit on the ET sensor. You probably have a broken wire inside the insulation at the connector to the sensor (right where it goes into the connector), a bent pin (common from people blindly forcing the connector on), or a spread socket (common when people jam meter leads in connectors instead of using the correct pin or back probes). These sensors typically never fail open but anything is possible. The code means the CIRCUIT is open - that includes wiring, connectors and sensor.
Disconnect the connector and check for 5V on the connector sockets. If you do not have it, check the insulation for a soft spot right where the wire goes into the connector and also pull on the wires - if broken the insulation will stretch. If it comes and goes with movement it's most likely a broken wire at the connector. Inspect that the pins are straight and the sockets are not spread. These are the things you look at in this case.
Last edited by Ed Ramberger; Nov 10, 2021 at 10:05 PM.
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https://gab.wallawalla.edu/~larry.aa..._res_chart.pdf
this is a thermistor chart. you can check sensor on the machine if the terminals are accessible. you can also back probe through the wiring but you have to consider induced resistance.
you can also remove sensors and place in a pot of water and slowly bring up the temp and see if they are skewed, make sure they are not touching the bottom of the pan.
this is a thermistor chart. you can check sensor on the machine if the terminals are accessible. you can also back probe through the wiring but you have to consider induced resistance.
you can also remove sensors and place in a pot of water and slowly bring up the temp and see if they are skewed, make sure they are not touching the bottom of the pan.
Stellar HDF Member
Joined: Sep 2017
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From: memphis
more than likely its one or more of the wires at the plug as Ed stated. while the bike is running take a pencil and wiggle each wire side to side to see if the bike stalls.
mine was the ground wire. I replaced the entire plug and the throttle induction plug.
bike runs better than ever.
mine was the ground wire. I replaced the entire plug and the throttle induction plug.
bike runs better than ever.
more than likely its one or more of the wires at the plug as Ed stated. while the bike is running take a pencil and wiggle each wire side to side to see if the bike stalls.
mine was the ground wire. I replaced the entire plug and the throttle induction plug.
bike runs better than ever.
mine was the ground wire. I replaced the entire plug and the throttle induction plug.
bike runs better than ever.
Good thought but I think you are thinking injector wire as a broken injector wire makes it stall - not an ET wire. He has an open circuit code for the ET.
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From: memphis
Last edited by memphisharley; Nov 13, 2021 at 07:41 AM.
Grand HDF Member
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From: Bates County MO
If the temp sensor wire is broken/unplugged, high resistance (open) is seen on pin 51 of the ECM, which the ECM tables interpret as ice cold (resistance of the sensor decreases with increased temperature)- and will immediately richen the mixture ( like cold idle rich). Easy enough to use an Ω meter to check continuity of the pink/yellow wire on ECM pin 51 (connector 78B) to pin A of the ET sensor (connector 90B). Ground side is ECM pin 61 (78B) black/white wire to pin B (90B)
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2nd Gear
Joined: Sep 2019
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From: Tucson
Update: Bad ET sensor. I realized I could use the Fuel Pak to read sensor temps (Yup, I'm a little slow). ET and IAT temps closely matched at room temperature. I had previously done all the tests in the EDM flowchart, so the EDM would have me replace the ECM. Since the fault had occurred while riding (sorry, didn't mention that in the original post), I figured I would check temps with the engine running. Just above 180 degrees the sensor reading dropped to 3 degrees. Double checked and then replaced the sensor. No problems since then.
I want to thank everyone for taking the time to reply to my question.
I want to thank everyone for taking the time to reply to my question.
Good to hear. Your additional info makes a lot more sense. The ET sensors don't usually fail open but they do fail where they drop in and out or skew significantly at different temps.