980G Alarm Fault Lights Issue

[YulMY]

980G
Machine SN: AYT249
Engine SN: BET5197

Hye all, recently we have replaced all harness for engine and transmission side due to most of them badly damaged.
Am currently facing a problem where the warning lights for hyd temp/hyd level/brake pressure/hyd filter bypass is turned ON.

We've performed the continuity test for all the sensors/switch to the monitoring ECM panel and all seems fine.
Initially, we suspected the harness in the cabin was the problem since it was not replaced, but the wires all seem to be properly connected, and all continuity test passed.
Also tested with new sensors/switch and the warnings all still ON.

Perhaps anyone here can help to point out what we're missing or have any similar experience in the past.
I have a feeling all these sensors/switch shares a twisted wire that I might've missed out.

Thanks in advance

 

[Nige]

Is the SERV CODE icon in the RH side of the Monitor Panel window permanently lit.?

 

[Bill P. Adam]

Have you check the data to ecm with SIS? Could be a bad cluster

 

[TheIrishStone04]

I worked on strip jobs during the era of the 980g’s, tough machines to beat. Mostly 2KR serial # with the mechanical 3406c’s so I might not be much help to you & no longer have SIS to look anything up. The twisted wires that you are talking about are data link wires, that is how your machine ecms communicate with the corresponding display modules. Your sensors send the signal to your ecm. Unless you have had an invasion of mice your harness within the cab should be safe. I agree with what Nige said first, see if your display is showing SERV CODE & verify what they are if so. Did this problem arise after you replaced the harnesses? If it did there is where you start, back track what you did. Since each of those sensors communicate with your hydraulic ecm separately. The next place to work on (correct me if I’m wrong any senior members) would be your ground circuit for those sensors as they might share a common wire. Make sure all the connectors are free of oil, voice of experience.. I’ve been burnt by that before. 99% of the time it’s something simple.

 

[Nige]

Well the OP has never been back since he first posted the question so I imagine we're never going to know.

 

[YulMY]

Hye all, sorry for the late reply. Had some issues with my health in the last 2 weeks.
As for codes, I've connected ET into the system and found only this code

650-9

Both for transmission and the monitoring system.
I'm currently arranging a CAT tech to come and have a look, but it'll be a massive help if we can pinpoint the source of this problem before he comes.

Thanks

 

[YulMY]

The machine had an accident previously that required us to replace the rear frame. Spare engine and transmission were installed, but ECM in the cabin were all reused. Same with their harnesses.

Harness for rear side of the wheel loader were replaced with new (engine, transmission, etc).
Not sure if this problem occurred during/due to the accident.
Can this be caused by a faulty monitoring ECM? Is there any procedure to check for a faulty monitoring ECM/display modules?

 

[Nige]

There is a communication issue regarding the Harness Code over the Datalink between the Powertrain ECM and the Monitor system.
See the attached. Also check your messages for an electrical schematic.

 

[YulMY]

There is a communication issue regarding the Harness Code over the Datalink between the Powertrain ECM and the Monitor system.
See the attached. Also check your messages for an electrical schematic.

Hye Nige thanks for the electrical diagram, turns out it was one of the pins for the connector not fully in contact. All of the warning lights working back to normal. The electrical drawing helped a ton.

But noticed the warning lights for brake pressure is ON.
It goes away after a while but comes back again when brake is pressed around 7-10 times. Parking brake even kicks ON when further using the brakes. Think this one isn't a false alarm and is mechanical related. All of this was done during engine ON.

Initially thought was due to not enough nitrogen pressure for the brake accumulator. But we have charged them back up to around 800psi and issue still there.

Took a pressure reading and the accumulator brake oil pressure cuts off at 2000PSI and continuously drop (slowly) when brake is applied, until around 1400psi where the alarm kicks in. If brake is released, pressure builds up back to around ~2000psi but really slowly. Is this the normal cutoff pressure?

Want to check all the possibilities before going to the pilot pump

Thanks in advance

 

[Nige]

It goes away after a while but comes back again when brake is pressed around 7-10 times.

That could be considered normal if you are pressing the brake pedal 7-10 times in quick succession with the engine at Low Idle. Basically you are discharging the stored oil from the accumulators. The brake pump does not have the flow capabilty to keep up with the demands of the brakes for oil at lower engine RPM. That is why the accumulators are there. They boost the flow when system demand exceeds the pump supply capability. Try repeating the test at High Idle RPM.

The low brake pressure alarm kicking in at 1400psi is about right.

 

[YulMY]

We've tested the machine again, during standstill at higher rpm, the oil pressure catches up to the demand.
However, during operation, further testing found that the bucket implements, steering, and braking sometimes gone mid operating. Would this be caused by the pilot pressure unable to catch up?

 

[Nige]

Would this be caused by the pilot pressure unable to catch up?

The best way to tell would be to run a gauge up into the cab and have the operator observe it while working. That would give you a clue as to what the pressure is doing during operation.