I am getting low voltage on various sensors such as ambient air temperature and engine coolant temperature. I am thinking it may have a ground problem. Could someone provide a schematic or the location of grounding lugs for this machine. Serial number CW902523. Thanks.
Can you list the reference numbers of all the Diagnostic Codes you are getting please. There may be troubleshooting procedures that will help you. TBH my suspicion is that you might have a problem with the 8v sensor power supply.
Here are the codes I have gotten: 110-4 Engine Coolant Temperature Sensor Voltage Below Normal. 171-4 Ambient Air Temperature Sensor Voltage Below Normal. E875-2 Low System Voltage Check the battery and alternator. E570-2 Unexpected Right Motor Forward Speed Detected Check the motor speed sensor and wiring. E569-2 Unexpected Left Motor Reverse Speed Detected Check the motor speed sensor and wiring. These alarms have typically been coming up after a restart when the machine has been running a while and is at normal operating temperature. They only come up briefly and then go away. I did check the voltage at the battery with machine off 12.45 volts, during start with starter motor running 11.78 volts and after start and voltage comes back up and stabilizes 14.35 volts. Any help would be appreciated.
Do those Codes come up in the order you have listed them or in some sort of random order.? Starting from the last two items on your list. E570-2/E569-2 occur when the poistion signal from the LH joystick and the drive motor speed sensor do not agree. It is possible that these Events could be as a result of low system voltage. E875-2 Activates when the engine is running and detected battery voltage is 12.25 VDC for 2 seconds. Check your message inbox for an electrical schematic.
110-4 and 171-4 have been coming up at various times usually after running the machine a while then stopping and restarting. The other three have only come up once.
So both those Codes are a result of a low voltage on the signal wire of the sensor in question. They are nothing to do with the machine system voltage. See attached, although the troubleshooting procedures may not show up anything unless a particular Code is Active at the time it is being diagnosed.
I worked through the grounds on my machine and thought I had fixed the problem. The 171-4 Ambient Air Temperature alarm still comes up occasionally. It only comes up after running the machine long enough to get it hot then shutting down and restarting. Increase in idle speed will cause it to go away. I thought the sensor for 171-4 was the ext-air-temp sensor on the schematic but it is not. I confirmed by unplugging it while the machine was running and got 172-4 Engine Inlet Air Temperature alarm. The only other temperature sensor I see on the schematic is a combo mass air flow and intake temperature sensor. Could that be it or am I missing something on the schematic. I tried disconnecting it the mass air flow sensor but as expected got mass air flow warning instead of temperature warning. Any help would be appreciated. I am getting close to giving up and hauling it to CAT.
What is labelled as the 377-6952 ambient air temperature sensor on the electrical schematic is actually shown as the inlet air temperature sensor by the parts manual. From a wider search that is the only location that particular Part Number is ever used on skid steers. Can you confirm that the wire numbers/colours connected to that particular sensor (N789 Blue & E585 Green) on your machine agree with the electrical schematic. It is a Passive not an Active sensor and so requires a different diagnostic procedure. See attached. From that attachment the ECM pin connections (Pins 34 & 25) also coincide with the electrical schematic.
The sensor I am looking at is labeled as sensor 130 on the schematic The location is shown below. The wire colors are blue and green. It is on the left side of the engine. I started the machine and then disconnected the sensor. I got 173-3 Engine Air Inlet Temperature Voltage Above Normal (I had incorrectly stated 172-4 earlier). I was expecting to see 171-3 or 171-4 Ambient Air Temperature Voltage.
From the label of the sensor on the schematic that would be logical, but as I stated earlier that sensor, despite the way it is labelled, is actually the Inlet Air Temperature sensor. Therefore the title "Engine Air Inlet Temperature" on the annunciator panel is correct. There is no ambient air temperature sensor on this model. Although when you come to think about it the temperature of the air entering the engine from the air cleaner assembly is going to be pretty much ambient temperature anyway. That's the one. The illustration I posted above was from the Parts Manual but they are one and the same.
So the 171-4 and the 172-3 come from this same sensor then?
They do. A totally confusing I agree. It took me a while to get my head around it. The logic as to why the same sensor is setting Codes for both 171 and 172 still escapes me. Maybe this dilemma is worth a word with your local dealer. Meantime I will consult with a few sources.
That N789-E86 BU-18 wire is fed power from the computer plug J2-Pin#34, and after going through the sensor the power returns to the computer plug J2 Pin#25 which is ground for it. If there is any weakness in those 2 wires it could act up intermittently until it lets go if that is contributing to the low voltage at the External Air Temperature Sensor. That Computer has other Battery positive and negative feeds that could be tested. Just something to look at and maybe quickly test with a 5 amp bulb with J2 plug disconnected, and batteries disconnected. Simon C
This comment that I posted on another thread recently may be relevant............ "Based on the number of issues that have been addressed on this forum over the years it appears to me that the Compact Equipment product line (Skid Steers, CTL, and MTL machines) generally suffer across the board from a lack of "slack" designed and/or built into their wiring harnesses. This especially applies to the engine wiring harness of the Kubota-powered product line. The result of this is that at any location where a harness is pulled into a tight curve, or where a zip-tie pulls a harness tight on to a ladder clip, there is always a possibility of vibration-induced failure of the individual strands of any particular wire inside said harness with absolutely no external indication that anything is amiss. For some reason this appears to be particularly prevalent with the wires that carry the medium & high speed CAN+ and CAN- signals and I have no idea why. That's another reason for load-testing individual wires within a harness one at a time using a 5A-rated test light. Often if they pop there may generally be at least some external indication."
There is also a lot of Positive power connections feeding the Fuses, Relays, Circuit Breakers, and computer Battery Positive connections that could be checked for Voltage drop. The fact that you stated that the problems usually occur after a hot restart points to at least having a look at the wiring. All I know is that a 10 gauge wire can carry 50 amps in the cold, but only 30 amps in a hot engine compartment. Your 18 gauge wiring will carry a whole lot less than that especially when very hot. Simon C
To the OP. Have you tried unplugging the MAF sensor with the key on and engine off.? What Code(s) do you get.?
You beat me to it Edit: bonus points if you can do this while the 171-4 is active.
I tried disconnecting the MAF sensor but got a Mass Air Flow Warning instead of Air Temp. Air flow must trump temperature. However I think the Ambient Air temperature sensor is built into the mass air flow sensor based on the attached. Both show five pins and one definitely refers to it as Ambient Air Temperature. I am going to attempt to back probe pins 4 and 5 on the sensor while not alarming and while alarming. Depending what I see there will try moving closer to the connections at the machine control. Thanks.
You are correct.