Auxiliary thumb rocker not working, Cat 287b

[Nige]

I checked the voltage at the joystick 12 pin connector. The "Key-On" voltage of pins 1 & 2 was 7.92 volts. ** that I reconnected & "key-on checked the thumb roller voltages between pins 2 & 3. It was 3.13 volts at center, 4.78 volts rolled down, and 1.47 volts rolled up.
I next checked the continuity of wires from both solenoids to the corresponding pins (#40, 42,& 58) on the 70 pin connector at the Aux ECM. It showed no break in the wiring

Your supply voltage to the thumb roller switch is good.
The roller switch output is a bit on the low side but it is varying correctly when you roll the switch in both directions away from the centre.

Next step is to measure the voltage on the same two wires as they input to the AUX Hyd ECM. That will be on Pins 52 & 53, the same two wires P996 Green & P997 Brown that you measured at the joystick connector. You are looking for identical voltages (1.47, 3.13, & 4.78) to the ones you measured between Pins 2 & 3 at the joystick connector. Again, like the joystick end, you will have to measure these by back-probing with the 70-pin electrical connector for the ECM plugged in.

 

[CrazyD]

Okay. I probed the voltage between pin 52 and 53 with the 70pin connector plugged into the ECM with the key on and are the readings: Thumb-roller at center reads 4.07 volts, roller down 6.27 volts, and pushed up 1.852 volts. Not identical to the previous readings but more or less in the ballpark, maybe?? What do you think?

 

[Nige]

I’m happy enough with those numbers. They prove that the that is same voltage leaving the joystick is also reaching the ECM.

Now unplug that same 70-pin connector. We’re going to try applying power direct to the AUX 1 and AUX 2 solenoids. This will test both the wiring harness integrity and that of both solenoid coils. Identify the following pins: -

Pin 1 (Batt+). Wire 128 Pink.
Pin 42 (Solenoid Source). Wire L998 Orange.

Pin 3 (Ground). Wire 203 Black.
Pin 40 (A1 solenoid). Wire P978 Green.
Pin 58 (A2 solenoid). Wire P979 Yellow.

You will need two short jumper wires. Start with the key OFF.
Connect one jumper between Pins 1 and 42. It will stay there for the whole test.

Step 1.
1. Connect the second jumper between Pins 3 and 40.
2. Turn the key ON. Can you hear the A1 solenoid click.?
3. Turn the key OFF, then repeat Step 2 a couple more times. Confirm that you can hear the solenoid click ON and OFF as you move the key from OFF to ON and vice versa. Turn the key OFF.

Step 2.
1. Connect the second jumper between Pins 3 and 58.
2. Turn the key ON. Can you hear the A2 solenoid click.?
3. Turn the key OFF, then repeat Step 2 a couple more times. Confirm that you can hear the solenoid click ON and OFF as you move the key from OFF to ON and vice versa. Turn the key OFF.

Report your results.

 

[CrazyD]

Thanks! I will get to that probably tomorrow a.m. & then get back to you!

 

[CrazyD]

Okay, The test from the 70 pin connector jumpered as you instructed showed between 3 & 40 key on "CLICK" sounded in one solenoid. And between 3 & 58 key on "CLICK" sounded in the other solenoid.
I assume that that is good news. BTW the solenoids are brand new from CAT.

Thanks a million!
WHAT NEXT?

 

[Nige]

The results of all the tests prove that the correct signals are reaching the ECM from the joystick and that both the wiring and AUX solenoids on the output side of the ECM are fine.

The conclusion is that you wasted your money on the ECM “repair” because it’s not working.

 

[CrazyD]

It has to be the Aux ECM then. The outfit gave a warranty, so when I send back and demand they fix it right... I can say that either Pin 40, 58, or 42 are not working properly. If they cannot repair... I'll follow your advice and get a good aftermarket replacement.

 

[Nige]

Personally I wouldn’t tell them anything apart from the fact that you have checked all the ECM inputs & outputs related to the AUX function and they are all working perfectly. Let them figure out what’s wrong with the ECM. Let’s face it they are allegedly the experts.

As I think I mentioned earlier if you go for an aftermarket ECM try yearnparts.com

https://www.yearnparts.com/catalogsearch/result/?q=216-0658

 

[CrazyD]

I really think you're the expert!!! And Thank You! for bearing with me on this. I'll report back after I get an ECM that works!! Best wishes!

 

[CrazyD]

HI again expert! I did not have to purchase a new aftermarket auxiliary ECM. The guys at ECM Engineering came through.... of course it was the third time I sent it to them. This time after installing the rocker switch is getting signal to the solenoids and it is working good! Thanks again for walking me through the steps to know where the problem was. I hope finally I can get some work done with this machine! Best regards to you!!