I am working on a Cat 321d serial-MPG00894. The machine hydraulics are very slow, it is giving an error code of 1590-5 This is the main pump sensor low voltage. Which sensor is the one to check on the pump? There are 3 sensors on the pump and a sensor on the hydr block located under the pump. I checked voltage on the sensor under the pump and it shows no positive current. It has ground at the plug. I am assuming this is the problem. I assume a broken wire somewhere. What are the wire numbers that come to the sensor? And should the voltage be 24v? I will check ohms between the plug and the ecm. I need to know the wire numbers. If this is the wrong sensor, let me know which one to check.. thanks
No it ain't - provided you quoted the Code correctly. It's the Main Pump Flow Limitation solenoid current below normal. It's part of the pilot lines. See attached.
ok, thanks for the fast reply. I will check the procedure that was sent.
Just to make sure I am testing the right solenoid. What is the exact location for the Main Pump Flow Limitation solenoid?
See the attachment above showing the pilot lines. It's Ref #24.
Is the J2 connector inside the cab or on the rear of the cab? How many wire plug?
The two wires at the pump flow solenoid do not match the wire colors given in the procedure. My harness wires are oem and are black and green in color. Black seems to be the negative. What wire number from the ecm feeds the positive pin on the solenoid. I will run a temporary wire overlay from the ecm wire to the pump flow solenoid and see if the code leaves.
J2 is on the Machine ECM located in the back side of the cab. It is one of two 54-pin connectors. You already have an electrical schematic. I sent it to you a few days back. According to both the electrical schematic and the troubleshooting procedure the wires to that solenoid on the machine side of the connector are White and Yellow.
Make sure you're on the correct solenoid first. If your Green wire is marked K879 you are on the wrong solenoid.
I checked the wire numbers on the pump flow solenoid. The black one is 235, can't see what number the green is. This does not make sense. I will dig deeper into the harness and see if it was repaired wrong. thanks
I got the wire fixed on the machine and the 1590-5 code went away. Now it is giving me a code of 1665-5 and 1666-5 This seems to be another hydraulic problem. Is there a procedure to check these codes like the last issue. The bulletin provided was awesome.
See the attached. A procedure for each of them but TBH I would be looking for something common in the wiring between the two components. Maybe wire M739 Yellow marked "PRV Return".?
Thanks so much for the response. To be sure I get the right sensor, is there a sensor location diagram for these two sensors?
I am also getting error code 617-5 air heater relay low voltage. Do you have the procedure for this one as well. Maybe the codes are all related like you said. Thanks for you help. This thing is trying my patience.
That's actually "current below normal" on the air intake heater relay. See attached.
According to what I can see on the schematic they are marked 101 & 103 on the machine location diagram. Also see attached. There are two identical solenoid valves #48. you will have to identify which one is which by the colours of the wires connected to them.
Is there multiple M739 wires that return to the ecm from the various sensors or do they all share 1 pin in the ecm?
All individual M739 wires will come back to one or more common points. At that point there will be a splice in the harness where multiple wires come in but only one wire leaves. All M739 YL wires return to a single Pin on the ECM - Pin 35 of Connector J2 marked "PRV Return".