Case 850K won't move foward or reverse

[GaryHoff]

Its possible that you have a bad brake potentiometer, but not likely.

The pin out information I have, is different than yours. Please refer to the following.
**pot = potentiometer

brake pedal pot. pin A, wire 523, to pin 23 at travel controller - is 5v from controller

brake pedal pot pin b, wire 525, to pin 25 at travel controller - ground from controller

brake pedal pot pin c, wire 521, to pin 21 at travel controller - signal out from brake pot.


Make sure you have the wires in the correct positions in the brake pot. connector. As per your last post you said wire 521 is in pin B, and my information says it should be in pin c. Maybe you took out the wires for testing, and put them back in the wrong spots. The pins are easily moved, so its a fairly quick check.

If the wires are in the right positions, my logic says it should work, as you have power and ground at the brake pot.

Do you have any fault codes now?

 

[fpgm04]

For clarity, what color wires are in each connector cavity coming from the sensor? If I recall correctly, from the sensor : 5v=red, ground=black, and variable signal was a blue wire.

Sounds like it would be worth confirming your sensors (old and new) are good or bad.

As you indicated your wife worked at tech school, does she or you have access to variable DC power supply that you could use? If so, then the sensor component could be checked out.
Checking would be simple, start with the loose sensor.
Set DC power supply to 5v.
Connect to the sensor to the power supply using alligator clips, or paper clips, whatever it takes.
Power supply + (5v) to sensor red, power supply – to sensor black.
Put your volt meter between power supply – and blue sensor wire.
Turn sensor shaft and see if you get <1 to >4 volts. If not, then bad sensor.

 

[vcat]

The print I have been using came with the service manual and it shows pin B wire on the potentiometer labeled 521. Wire labeled 521 is black.
Our print is obviously wrong. No wires have been removed from the connector. That is the wire I have been checking.

Today I checked for voltage variation on the blue wire, pin c, labeled 525 on my print but is actually wire 521.
Turning the potentiometer with a screwdriver I got .51v to 4.48v. Little better, huh? I put the potentiometer back
on and got 4.09v to 1.1v, petal up to petal down. This falls in the range you suggested, so I felt better - for a
little while.

I was able to get it calibrated on the second try with the procedure you gave me. I got through
calibration with "CAL DONE" on the dash display. I restarted the engine, brought the RPM up, put safety levers down and
it still won't shift into forward or reverse.

I checked fault codes and found 4: 4321, 4331, 4521, & 4533. These were all
recent, within the last 30 minutes or so. I cleared them, restarted and checked again. 4321 came back. I cleared, restarted
again and it did not come back. So there are no fault codes showing now but still won't take forward or reverse.

 

[GaryHoff]

Well, it looks like we have made some progress, but not enough to get it moving.

4321- Throttle potentiometer circuit out of range
4331- Inching pedal potentiometer out of range
4521- Bump up switch stuck on at power up
4533- Joystick CAN message fault, Directional control forward/reverse axis faulted.

Since it took a calibration, and you have the proper voltage range now, I would suggest that the brake pot. is working.

You need to run it again, and move the throttle and the joystick and brake pedal. Faults 4321, 4331, & 4533 will all stop you from moving. We need to know which one is coming on. If there is no faults, then it should work. Maybe it failed your first calibrations because of a bad throttle potentiometer. Since 4321 came back, it seems like the most probable one to check.

 

[vcat]

I tried to run calibration again today. I kept getting "RANGE ERR" and "CAL FAIL". I checked the fault codes and 4321 came up, nothing else. I cleared it and tried to calibrate again but failed. 4321 came up again and would not clear.

I think I have found the throttle potentiometer. It is on the RH side of the machine under the floor and somewhat in line with the decelerator pedal. Is that correct? I can only see part of it but it feels like it. I will need to tilt the cab to access it. Correct?

Should the voltage values be about the same as the brake potentiometer?

 

[GaryHoff]

I would agree that your throttle potentiometer is faulty too.

I believe that you have found the throttle potentiometer, and tilting the cab would probably help to gain access to it. I'm sure that you have tilted you cab before, but if not, there is instructions on the right door. Follow them exactly. I had a guy forget to removed his throttle linkage, and it damaged his injection pump. The other common thing to forget was to leave the left door open.

#28 should be the throttle pot.

 

[vcat]

I checked the throttle potentiometer today and got 4.96v on the red wire, .53v on the blue wire with no variation when the potentiometer was turned with a screwdriver. I will order one in the morning. Probably be here Monday.

I also a have a possible cause for failure. The potentiometer was soaked in hydraulic fluid. Apparently a leak near the drive shaft coupler. The coupler has been slinging the fluid. Haven't had a chance to check all the hoses yet.

 

[lantraxco]

Oil is a great thin film insulator....

 

[vcat]

I have been trying to get the throttle potentiometer calibrated. I get "CAL FAIL" at about the same spot each time. CAL FAIL comes up during, or at the end, of the second time I apply the decel petal to low idle.

No fault codes come up.

I haven't checked voltage variation yet. Should voltages be about the same as the brake potentiometer?

Low idle at the throttle is 850 to 900 RPM. Low idle on the decelerator is higher, 970 RPM. Could that cause a calibration problem?

 

[fpgm04]

Yes the voltages of throttle sensor should be in the same range as brake sensor.

I am not an expert on the calibration, but have you tried adjusting the stop bolt on the back side of the decelerator pedal so it can go further down and produce similar low idle rpm as the hand throttle?

 

[GaryHoff]

Yes, the throttle pot and brake pot should have the same voltage range. Since your calibration is failing at the decel pedal stage, make sure the decel pedal is traveling in the proper range. (throttle pot signal should not go below 0.5v or over 4.5v)

Any more fault codes? Does it move?

The calibration can be hard to do sometimes. Try moving the pedal very slowly Even try not pushing the decel pedal all the way to see if it passes.

 

[vcat]

I did get the dozer to take calibration but it still will not take forward or reverse.

I checked voltage on the throttle sensor and high end was 4.45v, low end was 2.4v. I adjusted linkage and got the low end down to 1.1v, high end at 3.5v. After it failed calibration several times, I went went through the procedure a little faster than I had been. I got "CAL POT, CAL INC, and CAL DONE". I shut the dozer off and restarted but it still doesn't take forward or reverse.

I have green lights on the proxy switches and there are no fault codes showing.

 

[GaryHoff]

So no fault codes now......... Does F or R show in the dash now? Speed up and down buttons still work on the joystick? Park brake light stays on in the dash?

What happens if you do the following : before key on, raise the throttle 1/3 or so, slightly push and hold on the brake and decel pedal, start the machine, then try and move forward or reverse.

With no fault codes it should be working now.............. Did you finish replacing all the fuses?

We may need to revisit the schematics............................. Maybe its not getting full power from the safety relays. Remove and check all your relays for corrosion. Swap them around while they are out.

 

[vcat]

Apparently I screwed something up. I started checking relays. There are 3 vertical rows, 2 relays in first row, 4 relays in second row and 3 relays in third row. I pulled top relay in third row, moved the others up and top went to bottom. I checked the dash display and there was no change. I did the same procedure on the second row and I got 3 red lights on the dash and 1 yellow light. Manual shows three red lights to be low oil pressure in the transmission, low oil pressure in the engine and low voltage in the battery. The yellow light is transmission controller encountered a fault. Dash display says "NO CAN" again.

I found a blown fuse. Bottom row, first fuse on left, 30 amp. I replaced the fuse but there was no change. I returned the relays to their original positions but no change. If I need to go back to square one, running checks, I can.

 

[GaryHoff]

Hmmmm. Well, I would start back in your fuse panel and relay panel. It seems that you moved something to cause this fault. I would suggest that you clean all the fuses and relay contacts. You may also have a bad relay. Did you change all the fuses? If not, then I would suggest to change all the fuses, regardless if they are blown or not. Seems like this is the best place to start.

 

[vcat]

I am still checking relay and fuse blocks. I did find a wire pulled loose at one of the relays. After I put it back on, the yellow controller error light on the dash, and the NO CAN on the display are gone. The 3 red lights, low oil pressure in transmission, low oil pressure in the engine, and low battery voltage are still on. (battery is not low and I haven't started the engine since the red lights came on, so engine oil pressure can't be measured) but the lights are on anyway.

The rocker switch doesn't bring up "FAULTS" so I have not been able to find any fault codes.

I replaced all fuses.

The bump up/bump down works fine.

I'm going back over tomorrow and finish cleaning contacts on the relay and fuse blocks.

 

[southernman13]

Man I take my hat off to you I'd a done blown that thin up!!! Just
Kidding but you are a very patient and diligent man. I'm following and rootin for you!!!

 

[vcat]

Thanks southernman13 for the support, although dynamite has crossed my mind.

 

[vcat]

I pulled all relays, cleaned prongs and scraped all connections. Corrosion was minimal but I scraped all I found. Scraped all fuse connections. While I had them out I checked continuity on the relay coils and continuity on the nc pins. All were ok. All wiring going in on the backside looked fine. Still have the red lights on the dash.

 

[GaryHoff]

A continuity test on the relays will not tell you much, as it doesn't load the circuit.

The red lights should be on until the machine is started. Do they stay on when the machine is running?