Have a cat 311 that I think the engine pickup sensor is bad. The sensor is reading 2.2k ohms when disconnected. Does that sound right ohm wise? Next question is what voltage should be going to the sensor? Out of the computer I'm not seeing hardly any voltage going to the sensor. Thanks
With a machine Serial Number I could look up the spec of the sensor, if one exists.
From what I can read on the tags serial number is 9LJ200201.thanks
Part number for the sensor in the manual is 5I-7579
Sorry, I can't find a resistance spec for it anywhere. TBH generally 2-wire speed sensors like that one are magnetic and work on the Hall Effect principle. They wouldn't have much if anything in the way of power coming from the electronic control.
Thanks I probably just order that sensor and hope that the problem.
Have you removed it.? What was the condition of the tip like.? Any metal chips stuck to it or was it chewed up.? Remove, clean, & reinstall might be a good 1st step.
Yes removed it metal all over the tip then reinstalled. Same as before won't go above idle. Acts the same when it's unplugged as it does when it's plugged in .
In my experience all the manufacturers speed sensors fail in two modes. They either short through with no ohms resistance between the wire connectors and the side of the metal sensor or they have infinite resistance. The metal that Nige brought up does interfere with the signal and will make for plenty of head scratching. It generally means the drive damper, and auxiliary drive gear for a pilot or auxiliary pump or the input bearing to the pump is in process of going bad. Do you have oil in the damper case?
So what exactly is happening/not happening? The engine won't go above idle or the sensor won't read above idle through the monitor? As with Nige, I can't find a spec for that particular sensor, but from experience I would say maybe about one or two hundred ohms. A multimeter with frequency measurement can give you a rough pass or fail test.
It sounds like you have a problem with the auto/manual switch and/or wiring. When the switch is in manual, are you able to change engine speed via the dial or the backup switch? Your post isn't clear. For now based on the info given, forget about the speed sensor. The serial number you quoted isn't good, but probably good enough. Attached schematic which will be correct provided that the last digits of your serial number aren't higher than 00261.
I read the S/N as 9LJ00201.......... completely missed the other "2" at the beginning.
So, under normal conditions with auto/man switch in AUTO, and with AEC activated, your issue is the engine won't go above idle right? Then when you switch it to MAN, and the A appears on the screen, you can bump the idle up/down using the back up toggle switch next to it right? If that's the case, yes a bad engine speed sensor could cause this, but so could any other fault with the electronic control really. On backupSw1 and backupsw2 on the drawling should one of those have power coming out of the controller or are they both just inputs? Yes they both look like inputs, they would tell the electronic control to forget about the engine speed dial and AEC altogether. I'd have a good look over the machine visually first and look for any rubbed, melted wiring, etc Just my thoughts. P.S. Type your replies under the quote when quoting someone.
hi, as you said 'I have jump the wires from the controller straight to the switches in the cab to bypass all the wiring and still doesn't work '. i think you should not connect the two wires from controller to the switches you mentioned. i assume that you mentioned here as switches for governor back up switch and speed change switch (toggle switches). if you do so there might be a chance of damaging the controller. because these 2 wires from controller brings the signal to operate the governor motor according to the input signals to controller from the speed change dial knob. so these 2 wires are out put from the controller.(B740-OR & B739-WH). so when the governor backup switch is at the auto position it connects these 2 wires to A763-GYwire & B751-YL wire which goes to the governor motor. when this circuit is completed then controller is operating the governor motor according to the input from the speed dial switch. when the governor backup switch turns to the manual position it by passes the controller (B740-OR & B739-WH wires) and connects the governor motor wires (A763-GY & B751-YL) to speed change toggle switch. this speed change switch has provided key switch voltage so when you move the toggle switch up and down it passes the current to both directions through the governor motor. therefore now you can increase or decrease rpm. as you asked 'On backupSw1 and backupsw2 on the drawling should one of those have power coming out of the controller or are they both just inputs?' they are inputs to the controller. at manual mode when you move the speed change switch up & down at that time only it sends the signal to the controller. i think in this case as you said that always 'A' displays on the monitor though you move the governor backup switch to auto & manual positions that means 1.Governor backup switch has stuck in side the manual position or 2. B740-OR & B739-WH these 2 wires from controller is faulty. you can bypass this switch by connecting ( B740-OR & B739-WH ) wires to the ( A763-GY & B751-YL ) wires at the governor backup switch. (refer the Schematic well) if this doesn't solve the problem then you have to inspect the 2 wires from controller ( B740-OR & B739-WH ) for there conditions. if both the backup switch & 2 wires are good then there may be a problem inside the controller. i think these are the 3 possible things could happen in this case according to my knowledge. Hope that this will help. good luck.
Yes the machi5eill Yes the A is always on the screen no matter which position the switch is in . We have never seen the A on the screen before until this problem started . Not sure but i dont think it will let me select AEC since i have the A on the screen. Yes the machine will not go above high idle unless you put it in man and use the toggle to increse the speed. Thanks
Does the speed change toggle switch work to change the rpm even in governor backup switch at Auto position. did you check that?
Yes I did check that it only rev up if it's in man.
Did you by pass the back up switch and try as i said from the earlier post ?
No I have not yet , I won't be around the machine until later tomorrow. Thanks for your help
Yes I bypassed the switch and it didn't help. I cut the wires b739 and b740 wires out of the controller and went with new wire from controller to the switch. Is there supposed to be any voltage on these wire ever ? I am never getting any voltage on either of them. Thanks
Yes. When governor backup switch at auto position & during acceleration from the speed chage dial knob, voltage between these 2 wires should be 0 - 20 volts.During deceleration 0 - ( -20 ) Volts. When starionary 0 V. Governor back up switch at the manual position & During acceleration voltage between these 2 wires should be 15 - 30 volts.During deceleration -15-(-30 ) Volts. When starionary 0 V. Make sure that the back up switch at auto position, these 2 wires connect with the A763-gy & B751-yl wires.( wires to the governor mortor) to obtain the correct voltage reading at the Auto position wires should not be disconnected. At the Manual position, out put wires from the controller disconnects from the A763-gy & B751-yl wires. That means voltages at the manual position means open circuit voltage of b739 and b740 wires. Did you check whether "A" indication went off after you by passed the backup switch ?
Yes the A stays on all the time even when i bypassed switch. My bother was running the machine a couple of weeks ago and the "A" came on for a couple of minutes then went away , then last week it came back on and will not go away, makes me thinks its a sticking switch or bad wire somewhere . Thanks for all of your help.
Did you check the above mentioned voltage parameters ?
i will tomorrow or this weekend , i will report back. thanks
Ok I found a troubleshooting guide in the manual. The first step it says to disconnect conn44 and check ohms between pin 4 and 5. It says it should read at least 1.5 ohms. I am reading 283k ohms. That seems way high but the book doesn't what the high end should be. That is the connection at the engine govern actuator. Is this my problem?
Yes. This could be. Because if the controller sees that much resistance(283k) instead of 1.5 ohms then current will not passes through it and controller will detect it as an open circuit. (This situation is equal to when backup switch is at manual position) This is may be why that indication "A" always stays on your monitor even backup sw at the auto position also. Because at the auto position also controller detect it as an open circuit. It is difficult to think how governor motor can still works at the manual mode even with, that much increase of resistance of the governor motor.
283k ohms seems extremely high when the spec only calls for 1.5 ohm minimum. Like @anuradha I think it indicates the governor motor is goofed but I can't show you anything to prove it.
Is there a way to read faults with the monitor?
yes, if you know how to enter the machine's data mode through monitor then you can see real time error codes & logged error codes. i think in this case "drew good" has the manual with him so he can refer to the "using data mode section" of the Testing & Adjusting manual.
Is it a 7Y5500 monitor?
yes, that is the part number for the monitor.
yes thats the monitor i have the display is clear but the push button area is in bad shape its hard to see which leds are on sometimes.
That is what i was thinking also about how the motor was still working . I took it apart today and pins 4 and 5 go to a little circuit board first then go to the motor . So i would think its a diode or something on the board that is bad . I and going to have to remove it all the way to get a better look at the board though. Once again thanks for your help.
If you have photos of the governor motor and its circuit please post some here.
How ever, did you check the voltage readings between the controller out put two wires for the governor mortor as i mentioned earlier, specially at the manual mode or when these two wires are open circuit ?
No I did not, I found that in the manual the other day and started there. Also I can take a pic later today.
Because i asked it, as "Nige" sir said above it says resistance of motor should be" at least 1.5 ohms." But we excactly do not know that what should be the max reading. If we can check the above voltage readings whether is it present, as i said at the manual mode then we can eliminate the controller from this issue.
Ok update I went and read the error codes . I have an e15 Which says govern switch is in man or motor circuit is open and I have a e16 which mean proportional reducing valve circuit is shorted to body ground. I read voltage 739 and 740 in the in the manual position and had 0v
Did you check the voltage according to the below process ? "Governor back up switch at the manual position or when these 2 wires are open in circuit, During acceleration from the speed change dial knob voltage between these 2 wires should be 15 - 30 volts.During deceleration -15-(-30 ) Volts. When starionary 0 V." During this test key switch should be at the on position.
I think you should follow the PRV troubleshooting procedure also to see that what will be the result on that particular issue as well.