Wiring Schematic

[partsandservice]

I need some help once again with a wiring schematic. For a cat wheel loader
KJP01095. Specifically I am dealing with a steering sensor. Thanks in advance.

 

[Mark250]

here you go

 

[partsandservice]

Many thanks

 

[partsandservice]

Just now digging into this issue. E192(3). 2201-3(3). It is my understanding that it means RH steer sensor open circuit. Using the schematic I have determined that the ground and reference are good as well as the signal wire that goes to the Impelent ecu as well as the transmission ecm . So I believe that the sensor is the open source but it is inside the cylinder . I would like to test this sensor before removing and disassembling the cylinder. Any idea how to go about this?
Thanks

 

[Nige]

You already have the electrical schematic. The attached ought to help.
Use the wire numbers listed on the schematic in preference to wire numbers on the procedure if they are different. The procedure is generic for various models.

 

[partsandservice]

Thanks Nige , that answer my question it specifically says that that is a pulse width sensor that can't be checked with a volt meter. Going to pull the cylinder.

 

[Nige]

Thanks Nige , that answer my question it specifically says that that is a pulse width sensor that can't be checked with a volt meter. Going to pull the cylinder.

Unless your DMM has a Duty Cycle setting on it - no.

 

[partsandservice]

It does not. I do have a scope however, but not sure it would do any good because it is locked out at this time and won't steer or release the parking brake. I assume the cylinder would have to move produce pwm signal.

 

[partsandservice]

I also I assume ET will be necessary to reset and calibrate or can this be done through the monitor with a password?

 

[Nige]

You should have a PWM signal even though the cylinder is not moving. The only thing you will see is that the % duty cycle of the signal does not change.
Usual range of PWM signal is approx 5-95% duty cyle with 50% duty cycle or thereabouts being the midpoint of the cylinder stroke.

When you extend or contract the cylinder from where it is now the % duty cycle signal from the sensor should increase or decrease depending on which way the cylinder moves.

 

[Nige]

I also I assume ET will be necessary to reset and calibrate or can this be done through the monitor with a password?

Dunno. Let me check.

 

[Nige]

It looks like ET is required to make the Steering Physical Stop calibration setting that is recommended when a cylinder sensor is changed.

 

[partsandservice]

We are just gonna replace the cylinder. The special tool 476 3486 is over 2K. I will then attempt to repair cylinder with homemade tools for a spare. Have multiple machines and left and right steer cylinders are the same. Will pick this thread back up at that point. Thanks

 

[rmllarue91]

Quick question if it's a pwm signal ex. on off square wave.
why is code either high or low voltage just trying to understand system design

 

[Nige]

Remember that the sensor has to be powered from the ECM, and grounded back to it. That's what the other two wires are in addition to the signal wire. If either the sensor power wire or the ground wire are interrupted (broken) it will create different reactions in the signal wire, and different FMI modes.
That's why the first couple of steps in most PWM sensor troubleshooting procedures are to establish that the sensor is being supplied with the correct voltage from the ECM, and is correctly grounded back to the ECM.

 

[rmllarue91]

This is just for understanding purposes not bashing cat but why check voltage when it does a self test when it says that's not a good troubleshooting test.
Ex. Pwm signal not present
Or pwm signal corrupted
Instead of voltage checks i get how they are doing it just seems it could be simpler and more accurate right from go.
I don't have a oscilloscope yet and don't see them used much in equipment yet but they seem like only accurate way to diagnose computer controlled electronics.

 

[Nige]

You generally don't need an oscilloscpe to check a PWM signal, at least on a Cat machine anyway. A DMM that will read duty cycle will do fine. I swear by the Fluke 87, had the same one for over 20 years now, and it's still a current model so it must do something right. Currently seems to be priced at about $300.

IMO unless as a starting point the stabilized supply voltage from the ECM is not checked, and also the ground back to the same source, no PWM signal can be relied upon as being correct. See below for the list of things to check for a typical PWM sensor fault. I'm not sure the self-test even checks the stabilized voiltage (5v, 8v, or 10v) that is being produced by the ECM.

The possible causes of this diagnostic code are listed:

• The ECM + supply circuit is open.
• The ECM - return circuit is open.
• The sensor signal circuit is open.
• The sensor signal circuit is shorted.
• Debris on the sensor.
• The sensor has failed.
• The ECM has failed. ECM failure is unlikely.

Going on a bit further, and maybe this is the answer to your question...........

The duty cycle of a PWM sensor is measured versus time. See the illustration below that shows what the output signal looks like at 10%, 50%, & 90% of the sensor Duty Cycle. Note that the only thing that varies is the "ON" time (grey shaded area) vs the "OFF" time (white shaded area).

The key here is that the "height" (red arrow) of the square wave is proportional to the voltage in the sensor signal wire - not to be confused with the stabilized voltage supplied to the sensor by the ECM.

So in addition to receiving a % Duty Cycle signal the ECM also has a range of upper & lower acceptable voltages (heights) of the square wave signal between which the signal is judged to be correct. Anything outside that range and the voltage in the signal wire is judged to be either "too high" (FMI03) or "too low" (FMI04).

 

[rmllarue91]

You generally don't need an oscilloscpe to check a PWM signal, at least on a Cat machine anyway. A DMM that will read duty cycle will do fine. I swear by the Fluke 87, had the same one for over 20 years now, and it's still a current model so it must do something right. Currently seems to be priced at about $300.

IMO unless as a starting point the stabilized supply voltage from the ECM is not checked, and also the ground back to the same source, no PWM signal can be relied upon as being correct. See below for the list of things to check for a typical PWM sensor fault. I'm not sure the self-test even checks the stabilized voiltage (5v, 8v, or 10v) that is being produced by the ECM.

The possible causes of this diagnostic code are listed:

• The ECM + supply circuit is open.
• The ECM - return circuit is open.
• The sensor signal circuit is open.
• The sensor signal circuit is shorted.
• Debris on the sensor.
• The sensor has failed.
• The ECM has failed. ECM failure is unlikely.

Going on a bit further, and maybe this is the answer to your question...........

The duty cycle of a PWM sensor is measured versus time. See the illustration below that shows what the output signal looks like at 10%, 50%, & 90% of the sensor Duty Cycle. Note that the only thing that varies is the "ON" time (grey shaded area) vs the "OFF" time (white shaded area).

The key here is that the "height" (red arrow) of the square wave is proportional to the voltage in the sensor signal wire - not to be confused with the stabilized voltage supplied to the sensor by the ECM.

So in addition to receiving a % Duty Cycle signal the ECM also has a range of upper & lower acceptable voltages (heights) of the square wave signal between which the signal is judged to be correct. Anything outside that range and the voltage in the signal wire is judged to be either "too high" (FMI03) or "too low" (FMI04).

View attachment 230603

Thanks nige that's what I was missing it checks voltage just as reference for self test monitoring I do check frequency with dmm I just want a scope lol thanks for help as an independent most of my computer education is automotive related I would love to do equipment manufacturer online courses.

 

[partsandservice]

Back on this job. Installed new steering cylinder . Steering sensor codes are no longer active. Steering will not activate and steering joystick is dead. When the parking brake is turned off it will not release and has code 2174-2 . Parking brake switch off at inappropriate time.
Went through the typical stuff, shift toggle I'm neutral, seat belt, cab door , engine door. ???. Calibration of the steer cylinder may necessary but no related codes. The owners of this machine have customer ET . Have not got it to my location yet.

 

[Nige]

2174-2 means that the engine was started with the parking brake switch in the OFF position.
To fix - Key off, move the PB switch to the ON position. When you start the engine next time the fault should have gone.

"Parking brake Switch Off. The operator needs to put the parking brake switch in the park position. This event is activated by starting the machine with the parking brake switch released (the ECM automatically engages the parking brake at startup)."