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Cat 299d drive motor sensor

Jimbo1268

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Apr 9, 2023
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I have a 2019 caterpillar 299d XE my left drive motor sensor is bringing up a code. I switched the wiring harness from the left to the right and it did not change anything on the display after I cranked it up and moved it. It still says we have, the wrong frequence or impedance or something like that was wondering if anybody had this experience to see why it would not change over to the other side when I plug the sensor in to the right side? Thanks in advance.
 

CM1995

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Welcome to the Forums jumbo!

Post a serial number so The wrenches on the board can help you out.
 

Nige

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It still says we have, the wrong frequence or impedance or something like that was wondering if anybody had this experience to see why it would not change over to the other side when I plug the sensor in to the right side?
If the Code didn't move to the other side the chances are it that relates to something that you DIDN'T move.
What Code exactly do you have - 2685-8 or 2686-8.?

Did you drive the machine far enough after you switched sides on the wiring harness.? If not I would try driving it a couple of hundred yards or so first just to be sure.
 

Jimbo1268

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No, we just moved it back and forth maybe 10 or 20 feet in the alarm comes on immediately when you move the joystick, but I can try switching the wires around and driving at 100 yards
 

Jimbo1268

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I test drove it for about 20 minutes today and every time you move the joystick, a red warning comes up that says E695-3. This is after switching the two sensors to opposite sides.
 

Nige

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"E695-3 - Unexpected Motor Speed Detection Disabled.
This event is an active only event (will not be logged). The event designates the unexpected motor speed detection control has been disabled due to a motor speed sensor circuit fault. A motor speed sensor circuit fault includes the motor speed signals and power supply (8V Power Supply). The event will only be active when the hystat transmission lever is in forward or reverse.
Reference the troubleshooting procedure for motor speed diagnostics or 8V Power Supply diagnostics, accordingly. Once the diagnostics are cleared, return the hystat transmission lever to the NEUTRAL and the event code will be cleared."


What was the original Diagnostic Code that you had. 2685-8 or 2686-8.?
I would also suggest that you swap the motor speed sensors back to their orignal positions before starting to troubleshoot this.
 

andrezzz2u

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Jun 6, 2023
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Location
Missouri
Most likely the speed sensor, had these go out in a few 299d's with us, make sure you also check the old speed sensor for metal shavings and the immediate connector to the sensor. Good luck..
 

JA Carney

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Nov 29, 2022
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TN
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Skidder rider
Most likely the speed sensor, had these go out in a few 299d's with us, make sure you also check the old speed sensor for metal shavings and the immediate connector to the sensor. Good luck..
I have just had this happen to my 2017 299D with the Red E695-3 followed by the Yellow 2686-8. I was in the process of securing the rear up on blocks for track removal and did not notice that my front sank. Of course, I had to take the door off to get in lol. I secured the magnet so I could disengage the parking brake (no jumper behind the seat) and my hydros are seemingly locked out. The icon will not go away on the panel. I do not know if my switch is bad or another issue is there. I am only a novice with a multimeter but i did get 1 reading on the switch so "assuming" it is good.

Oh, the codes are there for a short while and then later on are not even logged. Any points to the right direction, on either issue, would be much appreciated.
 

JA Carney

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Location
TN
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Skidder rider
I have just had this happen to my 2017 299D with the Red E695-3 followed by the Yellow 2686-8. I was in the process of securing the rear up on blocks for track removal and did not notice that my front sank. Of course, I had to take the door off to get in lol. I secured the magnet so I could disengage the parking brake (no jumper behind the seat) and my hydros are seemingly locked out. The icon will not go away on the panel. I do not know if my switch is bad or another issue is there. I am only a novice with a multimeter but i did get 1 reading on the switch so "assuming" it is good.

Oh, the codes are there for a short while and then later on are not even logged. Any points to the right direction, on either issue, would be much appreciated.
299D2XHP
CAT0299DADX201548
 

JA Carney

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TN
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Skidder rider
I have just had this happen to my 2017 299D with the Red E695-3 followed by the Yellow 2686-8. I was in the process of securing the rear up on blocks for track removal and did not notice that my front sank. Of course, I had to take the door off to get in lol. I secured the magnet so I could disengage the parking brake (no jumper behind the seat) and my hydros are seemingly locked out. The icon will not go away on the panel. I do not know if my switch is bad or another issue is there. I am only a novice with a multimeter but i did get 1 reading on the switch so "assuming" it is good.

Oh, the codes are there for a short while and then later on are not even logged. Any points to the right direction, on either issue, would be much appreciated.
CAT just called me to say that the jumper is a hydraulic jumper and is required.
 

Nige

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CAT just called me to say that the jumper is a hydraulic jumper and is required.
Which jumper are you talking about.?
Part Number 378-1028 to install in the connector on the floor behind the seat for a situation where the door switch/windshield wiper wiring harness has been disconnected.?
I'm fairly sure all you need to do is to disconnect the switch right at the door (illustration below) and then jumper Pin C on the connector to Pin A. If that doesn't work then jumper Pin B to Pin A. (Pin letters will be moulded into the connector)

1689182696728.png

FYI the way the switch works is that the ECM has to detect a connection to machine frame ground on one wire of the G943/G944 pair and open circuit on the other to confirm that the door is closed.
 
Last edited:

JA Carney

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Thank you for the feedback. My apologies for the late reply. Local CAT gave me one since it was not in the machine but was apparently supposed to be in there. Now I just have to replace the left drive motor speed sensor.
 

Nige

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Thank you for the feedback. My apologies for the late reply. Local CAT gave me one since it was not in the machine but was apparently supposed to be in there. Now I just have to replace the left drive motor speed sensor
It definitely should be in the machine. Usually it is zip-tied to the machine harness connector on the floor behind the seat. Sometimes they go walkabout…

What Diagnostic Code do you have.? Have you done any troubleshooting.? The problem could just as easily be a wiring issue. Swap the LH & RH sensors over and see if the problem changes sides or stays where it is. You will have to run the machine a hundred yards or so to get any speed sensor code to clear.
 

JA Carney

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Yes. CAT field service said a tech may have forgotten to put the jumper back after correcting issues. Understandable.

I did switch them and the same (different side) code came up. It was constantly alternating between the red Event 695-3 and the yellow 2686-8. I chose to stop running this machine completely because the alerts kept blocking the backup view lol.

I managed to get the new sensor installed last night but chose to finish with the hoses and covers this morning.
 
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