I am looking for suggestions. 2005 caterpillar 247b. Key switch. Turned to the on position, machine dash lights all come on and go through their start up cycle, then go out. Even the park light. With it not being in park, the key switch will not start the machine. Fuses and relays all bench test good. Power to the Key switch. With key in the on position, I can go jump the starter directly and it will run but no hydraulic flow to tracks or arms. Cooling fan spins as it should whick I believe tells us the hydraulic coupler is good. Door switch is jumped. Seat switch is jumped. New arm bar switch. New park switch. I am looking for any recommendations. Thank you.
A Serial Number would be a good start, because that gets you an electrical schematic. Have you checked all the battery cables and cab/engine to chassis grounds yet.?
Both new cables. cleaned connections. I have a good tested ground throughout the machine. I did find a broken spade on fuse box plug and installed a new fuse box today. I have owned the machine since new.
The start relay control wire ( A346-EA16 BU18 ) is fed by the Interlock Controller Pin number 64 which is wire ( 306A11 GN 18 ). for the interlock controller to send the power some of the safety systems have to be in place and working. The power from that controller if you follow it on the schematic which Nige sent me a long time ago goes through multiple plugs that could be corroded or a wire even broke off. Why not try to see if you have power at the Pin 64 with a back probing pin with the key in the start position and held there for 5 seconds. You stated you tested the relays but is the signal going to the relay. Power to control the relay enters the relay via wire number ( A346-EA16 BU18 ). I am assuming your battery is fully charged and that you have good ground cables. Test these two items first, I would check at the relay signal wire first. Let us know what you found. Simon C
Thank you. We are NOT getting power to the relay with the key in the on position. If you still have the schematics, could you share even some it with me? I also have tried other known Good working key switches. Grounds are good. I’ve had an issue before where I couldn’t get the machine OUT of park which was remedied by a new brake solenoid but this issue. Is is it won’t go INTO park. I agree, I relieve it has to do with the the interlock system as well.
It is not key in the On position, but has to be the key held in the Start position that sends the power to the blue wire of the Start relay not the power relay. This may be what you meant, just clarifying to make sure you are not chasing something that is not there. If Nige does not send you the schematic, he may be tied up , I will send the one I have later this day, I hope it is the most current. Have you checked the Interlock ECM pin 64 to see if it is sending the signal with key held in start position. Cause if it is sending you have a harness problem of some kind. Need to start somewhere. Simon C
Check your message inbox for a schematic.
Thank you for the help. It is much appreciated. Machine has been down for months when I waked away in frustration and lack of time. . But I am back at it. Correct. Key in start position send no signal to relay. Thanks again.
Have you looked under the floor and checked the condition of the Operator Interlock Control and the AUX ECM.? They tend to suffer from water/dirt ingress because of their mounting location. You will need to get into that area to check the output of Pin 64 on the Interlock Control as suggested by @Simon C
I did. Exterior looks intact and not all corroded and deteriorated. Connections were as clean as new. Thank you.
That tells me two things, either the interlock is putting out and the signal is broken on the way to the start relay or the interlock is not putting out the signal via Pin 64. If it is putting out then the harness has an open in it somewhere. If interlock is not putting out something is telling it that something is not safe, or it is possibly faulty. A person does not want to fire off the parts cannon only to find out it was a connection problem. Has happened too many times on this site. Would be a good idea to test the case of the controller to battery ground to see if there is too much voltage loss on the ground side of things with the key in the start position. Those controllers if my memory serves me right has a tiny ground strap going to one of the bolts on the frame. Test some of these things first and let us know what you find, may have another cheap suggestion to check. Simon C
My suggestion would be a couple of things: - 1. With the key OFF unplug the 70-pin connector from the Interlock Control and apply batt+ to Pin 64 (wire 306-GN). Does the start relay click.? 2. Check that all the inputs to the Interlock Control from safety-related devices are working correctly. This would include the park brk solenoid, park brk switch, armrest switch (both N/O & N/C legs), & implement lockout switch.
I did put power to #64 pin and did NOT get any power to the relay. I will complete further checks tomorrow when I have more time. Thank you.
Start following Pin 64 output of controller on the schematic and it will go through multiple plugs to get to the start relay. The page on the top of the schematic has all the locations of plugs on the machine. There must be a problem in one. It may take a while to take apart and clean and reassemble. If you see an easy to get to plug that the signal passes through then you can test at that location and move downstream or back up stream depending on if the signal makes it to that spot or not. Simon C
Out of curiosity, how many hours on that vintage of machine. I am guessing a lot? Simon C
Like Simon I’m also thinking green crusties somewhere, maybe in more than one location. Especially when the performance of the warning light panel is taken into consideration.
Good point about the warning light panel. Must be one plug or location in tough shape.
in testing pin 64 yesterday, I forgot we were testing some other things and had some junctions unplugged. Everything get plugged back in the way it’s supposed to be and I tested pin 64 again and it DOES turn the starter when I put power to that pin. My to understand that the interlock system is a ground system? Meaning, what’s all the switches are in the run position, there is one common ground? The fact that my machine will not go into park and keep the park button illuminated maybe where my issues lie
The Interlock Control is far more complex than "a ground system". It's basically an ECM by another name. The logic circuits contained in it are designed in such a way that, if it sees ground on Pin A then do X, or if it sees ground on both Pin A & Pin B then do Y. The paths to ground from the IC through thevarious switches are inputs that the software then interprets and does what it's programmed to do based on binary ground/no ground conditions. My bet all along has been that the Interlock Control is bad but you have to go down every rabbit hole testing until there is no alternative left but a bad control. Having established that powering Pin 64 cranks the engine up now you are left with verifying the inputs to the IC from the list of switches I posted above in Post #12.
I will keep at it. Thank you all for the input and direction. Will keep you posted.
4000
Wondering what you thought Nige of Harrison6jd having to test some of the wires that go to the Arm switch, seat switch, park brake switch with a bulb and power to ground. I am using on switches to not overload them , a 1156 Bulb with receptacle from the auto store as it only uses about 2.1 Amps and those wires and switches can handle that in my experience. Because the switches work does not mean the harness is not degraded somewhere and the interlock computer translates it into a bad connection. As you said there is quite a few rabbit holes to test before spending big dollars on the controller. Any words of wisdom Nige, am sure he wants to find real cause before firing the parts cannon. Simon C
Considering the behaviour of the park brake warning light when the key is turned ON, I would suggest to backprobe Pin 70 (wire 674-BU) for the parking brake lamp and observe what happens to the voltage on that wire WRT to machine chassis ground when the key is first turned ON.
It’s been a few months but I wanted to reply. Thank you all for the information and suggestions and insight. I did exhaust all options before sending the ECM to be checked. It did in fact get moisture inside and after testing, it showed Break in communication within the ECM. It’s been repaired and the machine works as it should. Thank you.