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  1. #1

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    Water temp sensor continuity MSX 140

    Does anyone know in regard to the MSX 140 water temp sensor if there is a static reading from the PK/BlK wire on pin 13 of the 40 pin connector? According to the schematic it shows there should be around 985-1015 ohms. Since the other side of the sensor is ground I should be able to see that reading from pin 13 and the other side of the volt ohm meter to ground correct? It is open on my readings now. With an open could this cause the 3500 limp mode?


  2. #2
    martincom's Avatar
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    The 985 - 1015 ohms is the resistance of the sensor itself, disconnected from the harness. I'm gathering that you are attempting to measure the resistance of the water temp sensor while it is "in circuit", which would be the incorrect method. That being said, measuring "in circuit" would result in a reading that is lower than normal. As you are reporting it reads as an "open", it would be defective. Unless you blew the fuse of your meter by measuring in a live circuit.

    I can't recall how it reacts when disconnected (open), but a SLOW mode (limp mode) is reasonable to expect.

    For testing purposes, you can replace the water temp sensor with a 1000 ohm resistor, which is the value the temps sensor indicates for 70F or thereabouts.

    There was a rubbing/abrasion issue on the water temp sensor (exhaust) in which a rubber bumper was added to prevent. If your doesn't have it, that could be what caused it to fail. Polaris released a bulletin in this regard. Check K447's home page for a link of exhaustive Polaris info he has compiled. I'm sure he'll have something there about it.

  3. #3

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    Thanks for the info. I was reading with the 40 pin connector disconnected or open circuit and read from pin 13 itself to ground. I will try the 1000 ohm resistor and see if that clears the issue. Thanks for the feedback. i will check K447s page.

  4. #4
    martincom's Avatar
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    Gotcha. You may want to check it at the sensor connector itself. It is easy to access. The sensor has about an 8" tail and the connector is typically rearward of the PTO cylinder. Of course, if you have continuity there, then you have a harness issue. Unlikely, but easy to check.

  5. #5

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    Thanks that's good to know. I will check it. Merry Christmas

  6. #6

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    I finally got to get back to the MSX and took the sensor out. It is 1005 ohms which is correct. I checked continuity on pin 13 of the 40 pin connector to the sensor connector and there is continuity. i assumed the other side was a ground but looking at the schematic it looks like it goes to to one of the BLK Splices which have Blk 2, 3, 4 and 5. In tracing those leads back on the schematic Blk 2 goes to Pin 5 of the 40 pin connector, Blk 3 goes to one leg of the ESP controller, Blk 4 is tied to the water temp sensor I am working on and Blk 5 goes to the air temp sensor. So I was assuming I would see the Blk as a definitive ground but there is some interconnection between other devices. So I wonder what the relationship is. It seem the water temp, air temp and ESP all have relationship to pin 5 on the EMM. So I would assume the pin 5 on the EMM is what initiates the SLOW mode. Am I right?

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    martincom's Avatar
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    So I would assume the pin 5 on the EMM is what initiates the SLOW mode. Am I right?
    No. Pin 5 of the 40 pin EMM connector is "analog ground" and is connected to the engine ground. All the harness grounds connect to the engine block at the left rear corner, at the base of the PTO cylinder, exhaust side. The negative battery cable connects at the same bolt. A cooling hose and the reverse cable may be concealing it. Check that bolt for looseness. If it is tight, then you may have damage to the harness and will need to trace it out utilizing the wiring diagram as a reference.

  8. #8

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    I guess I'm confused then. Does the EMM provide the ground to pin 5. Because of the four Blk leads in the Blk splice I see no analog ground on the connector side of pin 5. See the splice i am referring to below. It's not saving my image .

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    Last edited by raydmo; 12-26-2016 at 11:42 PM. Reason: add diagram

  9. #9
    martincom's Avatar
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    Does the EMM provide the ground to pin 5.
    Yes. Refer to the fuel injection section of the manual. Page 4.9 indicates pin 5 is the ground/return for the air, water & TPS sensors and denoted as such. If you view the block diagram of the injection system on page 4.7. It is unclear if the "analog ground" is bonded to the chassis ground (pins 1, 11, 21, 31, 10, 20, 30) within the EMM. The fact they are identified as two separate ground paths and the block diagram does not depict any interconnection, I would tend to conclude they are not.


    Usually, if they are not bonded to chassis ground, they would be denoted as a "return" and not a "ground". My first reaction, as they are denoted as an "analog ground", would be they would be bonded to chassis ground with possibly some additional noise filtering. However, I have chased my tail one to many times when making assumptions and have learned the definition of "assume" far too many times.

  10. #10
    casey67's Avatar
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    Quote Originally Posted by raydmo View Post
    I finally got to get back to the MSX and took the sensor out. It is 1005 ohms which is correct. I checked continuity on pin 13 of the 40 pin connector to the sensor connector and there is continuity. i assumed the other side was a ground but looking at the schematic it looks like it goes to to one of the BLK Splices which have Blk 2, 3, 4 and 5. In tracing those leads back on the schematic Blk 2 goes to Pin 5 of the 40 pin connector, Blk 3 goes to one leg of the ESP controller, Blk 4 is tied to the water temp sensor I am working on and Blk 5 goes to the air temp sensor. So I was assuming I would see the Blk as a definitive ground but there is some interconnection between other devices. So I wonder what the relationship is. It seem the water temp, air temp and ESP all have relationship to pin 5 on the EMM. So I would assume the pin 5 on the EMM is what initiates the SLOW mode. Am I right?

    See K447's post that follows for an explanation of the 5th splice.
    Last edited by casey67; 12-27-2016 at 02:05 PM. Reason: incorrect information

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