312b Pump Delivery Pressure Switch - how do I check it

[CatKC]

Can anyone tell me how to check the Pump Delivery Pressure Switch ???

I am NOT getting any ERROR CODES but in checking everything I know how to check I need to check the pressure switch.
I OHM it out, running and not, and get no continuity between the 3 leads but I don't know if this is normal or not.
I'm working on a 'no RABBIT speed' problem.

 

[Nige]

I think what you are referring to is actually the pump pressure sensor, not a switch.

To see if we're talking about the same thing, can you confirm that the colours of the 3 wires on the sensor are yellow, brown, & black..? If you go from the sensor back to the first wiring harness connector on the machine side of that connector you should find the following wires. 200 black - connects to Black, K997 blue - connects to Yellow, and K904 Green - connects to Brown.

200 Black should have continuity to ground.
You should have 24V between K997 Blue & 200 Black with the key on.
K904 Green is the signal wire and it would be a good idea to make sure that there is continuity between the harness connector at the sensor and the 7-pin connector on the back side of the monitor. K904 Green also connects to Pin 2 of connector A on the pump control.

Post your Serial Number. I may have the Electrical Schematic for your machine.

 

[CatKC]

YOU are correct- it is SENSOR not switch. It is on top of the pump.
I will do the checks you requested.
In the mean time the SN is 9GR00432K.
I am trying to figure out why it won't travel in HIGH/RABBIT and am foling a -flow chart- I got off the internet after checking everything I know to check.
I went into SERVICE and 62-4 and the 312 will run RABBIT when forced.
Then I went into 16-13 and te TRAVEL PRESSURE SWITCH checked out OK.
No error codes, so I need to check the SENSOR.

I'll get back after I do the checks. Thanks.

 

[Nige]

I have the electrical schematic for your machine. It may be an idea to see where the wires go from the pressure sensor and do the relevant power and/or continuity checks just to make sure that there are no problems related to the machine wiring harness.

Send me a PM with your email address if you want it.

 

[CatKC]

I have the electrical schematic for your machine. It may be an idea to see where the wires go from the pressure sensor and do the relevant power and/or continuity checks just to make sure that there are no problems related to the machine wiring harness.

Send me a PM with your email address if you want it.

Sent the address. . .
The wires are labeled as you indicated black-green-blue. The continuity to ground and voltage checked OK.

On thing that puzzles me and where you might enlighten me . . . when I go into SERVICE the initial display (10) indicates "1" LOW for the 'Status of Travel Speed Switch' -no matter- if the engine is running or not or if I am traveling or not when the 'speed' is set to RABBIT or TURTLE. I don't know what this is checking but I would think it would have to show "2" HIGH in order to travel FAST.
Do you know what this is checking ? or what might cause the indication if it is not correct ?

 

[Nige]

The schematic is on its way. A quick glance revealed inputs to the electronic control from a travel pressure switch. It might be worth checking continuity in any wire that has any relation to the travel function. You already know that if you put your machine in service mode the 2-speed travel works, that eliminates the 2-speed solenoid and its wiring at least.

 

[CatKC]

The schematic is on its way. A quick glance revealed inputs to the electronic control from a travel pressure switch. It might be worth checking continuity in any wire that has any relation to the travel function. You already know that if you put your machine in service mode the 2-speed travel works, that eliminates the 2-speed solenoid and its wiring at least.

Do you have any ideas RE: the 'Status of Travel Speed Switch' indicator as to what it is checking ?
I am -hoping- it is not the CONSOLE RABBIT/TURTLE switch which -shows- RABBIT MODE being ON.


*** BTW could you RESEND the schematic as an ATTACHMENT as it did not come thru correctly.

 

[CatKC]

Thank you for your assistance and the schematic -
The schematic was -incorrect- when it indicated the "Hydraulic Pump High Pressure Sensor" was in location -A2- . . . .however it gave me enough information so I could, with other information I gleaned off the internet, find the problem.
It appears the Pump Pressure Sensor is defective.
ANOTHER problem I fixed was the WIRE going to the Sensor would SHORT to the ground wire if moved around. The ground wire had a short to the others where it was banded/clamped on the pump.

*** For those who would like more information on checking the Pump Pressure Switch:
You can check the pressure 'indicator' in Service Mode & 21.
Monitor should read around 34,000kPa or slightly more- *40,000 means OPEN, *00,000 means SHORT. AND the reading should vary to less kPa when operating bucket/boom.

For a check -at the sensor-:
The GREEN wire is the feedback, the BLUE wire is "hot" or 24 v. BLUE should be 18-25v to ground.
Measure GREEN to GROUND-
Operate BUCKET control lever - reading should be .5-2.5V when in neutral. When relieved 8 - 11.v
If the monitor reading is incorrect and the voltages are wrong, the sensor is bad.