Cat E120B Pressure Reducing Valve / Overall Operating Force

[Machinist]

I have been tasked with repairing a 1994 Cat E120B. The machine bogs down when moving heavy loads and the swivel is a bit too fast. The controller displayed the following lights:
L1 L4 L7 on steady, L6 blinking.

Operating under the assumption the pressure reducing valve was the culprit I ran through the PRV System Problem Checklist. I measured the resistance across the coil to be 60ohms, out of range; and kept going through the checklist confirming the wiring harness had no open legs.

I replaced the PRV with a new one from Cat, the lights on the controller changed, but the problem persists. The lights now show: L1 L4 L6 on steady. I cannot find this exact code in the manual.

Do I need to test or adjust the input/output characteristics of the new valve?

Reading the checklist for Overall Operating Force or Overall Operating Speed Insufficient: 1. the backup switch is in the ‘off’ position, 2. The next check is that the controller has no lights, which it still does, but if we skip that for now, the final check is 3. the input/output characteristics. The end is “replace controller”.

Any thoughts of what is a likely problem, before we spend more money on parts? Thanks

 

[Nige]

Serial Number would be a good start.

 

[Machinist]

SN: 6JF00737

 

[Nige]

Is the attached manual the one you are working with..? If so it states that adjustments are required if the PRV has been replaced.

 

[Machinist]

Most of the information looks the same as the paper manual I have. My manual doesnt mention making adjustments after replacing, but it makes sense. Thanks

 

[Machinist]

I am following the previously attached set of instructions, but having an issue on part 1 (engine high idle input) step 7, paragraph 1.

When I hold switches 1 and 2 for 3 seconds, L3 is blinking red, L4 is blinking green, L6 is lit, the buzzer sounds and the "control" lamp is lit.

If I release an hold them again, L7 lights while switches 1 and 2 are pressed, but the buzzer does not stop. Holding them again for 3 seconds does not change anything. It sounds like the controller is not accepting the new high idle setting, but there are no troubleshooting steps.

AEC and backup switches are off.

(edited for clarity)