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catmastertech
catmastertech, Technician
Category: Construction and Road Equipment
Satisfied Customers: 1831
Experience:  Field service technician for CAT 19 years.
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cat 928G , put the control lever in forward and the reverse

Resolved Question:

cat 928G , put the control lever in forward and the reverse beper goes on, the unit try's to move forward, when you build up revs the trans drops into neutral, yu put control lever into reverse, beeper goes on and does not move, put back in forward and beeper does not go on and then goes on and creeps forward until revs built up again
Submitted: 1 year ago.
Category: Construction and Road Equipment
Expert:  catmastertech replied 1 year ago.
-Could you explain your situation a little more?
This is a strange problem I have never seen before but, I would like to help find a solution.

Did any of the previous repairs fix the problem? (even for a short time)

What work has been done? (major parts)

What work environment is this loader used?

How many hours are on the loader and transmission?

What is the machine serial number?

Are fault codes present?

Have you performed any pressure testing?

If so, what are the results?

Please let me know what you can and I will research the problem to see if I can find something related to this issue.
If you are planning to make the repairs, please tell me what tooling and facilities you have available.

Thanks, Donnie.
Customer: replied 1 year ago.

serial number 7SR01078, 12000 hours on the machine, 3000 Hours since $25000 spent on transmission. machine is used in grain handling. this is all the imformation i have at the moment.


 


thank you

Expert:  catmastertech replied 1 year ago.

Thanks for the reply. You have offered a clue in your response that would cause me to question the wiring. I am sure you have had problems with mice eating the insulation of farm machines.

Have they every damaged this machine?

This would likely cause the ECM to have codes.

I will be back online tonight (EST US). If you can send me details on the other questions, I can help you more with this problem.

Thanks, Donnie.

Customer: replied 1 year ago.

found the code 69 on the ecm flash codes, turns out it does operate normally, just the reversing beaper is on in forward gear

Expert:  catmastertech replied 1 year ago.
Code 69 is for Invalid Downshift Switch. This is the button on the top of the loader control to force transmission into first gear for loading the bucket when pushing into the pile.
This is common when the switch has failed and is stuck down. Could also be a shorted wire.

Below is a guide to test the shift lever. It is more to find if the lever is not working but, it will be a good reference to see if you have current bleeding over in the reverse relay to operate the alarm.

Transmission Control (Shift Lever) <<<click here.

Some machines had a different shifter, this could be an updated version if yours has been replaced. Below is the schematic for that shifter. It is electronic and doesn't have a guide to test it.
graphic
graphic
The wire from the backup alarm relay to the alarm and backup lights is a brown wire marked 321. The orange wire marked 331 is from the shifter to the relay switch.

graphic
Here is information to test the downshift switch.

This diagnostic code is recorded if the control detects a ground in the downshift switch. The ground must be present for more than 3 minutes.

Connector contact 12 is for the downshift switch.

Test Step 1. CHECK THE CIRCUIT FOR PROPER OPERATION.

     

  1. Turn the key start switch to the OFF position.

     

  1. Disconnect the harness connector from the ECM.

     

  1. At the harness connector, measure the resistance from contact 2 to the switch input.

     

  1. Measure the resistance in each of the two positions of the switch.

Expected Result:

One switch position should show resistance of less than 5 ohms. One switch position should show resistance of more than 5,000 ohms.

Results:

     

  • OK - The measured readings are correct. The switch is correct and the switch harness is correct. Proceed to test step 3.
  • NOT OK - The measured readings are not correct. The switch is not correct and the switch harness is not correct. Proceed to test step 2.

Test Step 2. CHECK THE SWITCH

     

  1. Turn the key start switch to the OFF position.

     

  1. Disconnect the harness connector from the ECM.

     

  1. At the switch, measure the resistance from contact 2 to the switch input.

     

  1. Measure the resistance in each of the two positions of the switch.

Expected Result:

One switch position should show resistance of less than 5 ohms. One switch position should show resistance of more than 5,000 ohms.

Results:

     

  • OK - The measured readings are correct. The switch harness is faulty.

    Repair: Repair the harness or replace the harness.

    Proceed to test step 3.

  • NOT OK - The measured readings are not correct. The downshift switch is faulty.

    Repair: Replace the downshift switch.

    Proceed to test step 3.

Test Step 3. CHECK IF THE DIAGNOSTIC CODE IS STILL ACTIVE.

     

  1. Remove the connector from the ECM. Inspect the contacts and clean the contacts of the harness connectors.

     

  1. Reconnect all harness connectors.

     

  1. Turn the key start switch to the ON position.

     

  1. Enter service mode of the Caterpillar Monitoring System and clear all inactive diagnostic codes.

     

  1. Operate the machine.

     

  1. Determine if CID 0621 FMI 02 is present.

Expected Result:

CID 0621 FMI 02 is present.

Results:

     

  • YES - CID 0621 FMI 02 is present.

    Repair: The problem has not been corrected. It is unlikely that the ECM has failed. Perform the previous Steps again. If the cause of the diagnostic code is not found, replace the ECM. See Testing and Adjusting, "Electronic Control Module (ECM) - Replace".

    Stop.

  • NO - CID 0621 FMI 02 is not present.

    Repair: The diagnostic code is NOT present. The problem does not exist at this time. The initial problem was probably caused by a poor electrical connection or a short at one of the harness connectors that was disconnected and reconnected. Resume normal machine operation.

    Stop.


Let me know if you need more help. I will be glad to do what I can. Thanks, Donnie.
Customer: replied 1 year ago.

turns out it is in 1st gear in both forward and reverse and it is a warning beeper in the cab when you select forward

Expert:  catmastertech replied 1 year ago.
If it is stuck in first gear, disconnect the downshift button on the lift control lever. This can hold the transmission in first gear.
Also try using the autoshift control in the on and off positions. Then try the neutralizer switch in the on and off positions. Shift all speeds and both directions to see if all gears can be selected. Auto-shift only works when speed is high enough to advance to the next gear.
The beeper in the cab is due to the parking brake switch is stuck in the on position or the parking brake lever is not going all the way down.
Customer: replied 1 year ago.

it appears a wire had come off the park brake micro switch, when the park brake alarm is on will this mean that it only has 1st gear

Expert:  catmastertech replied 1 year ago.

The park brake wire is the cause of the alarm.

The (first gear select) downshift button is stuck down on the lift lever or the wires are shorted to ground. This will cause the machine to drop back to first gear all the time.

If the button is stuck, remove the front cover of the console and disconnect the button connector. If the button is working, inspect harness for short to ground.

The guide I sent you for the downshift switch is how to test for this problem.

NOTE; If the auto-shift button is on and the transmission speed sensor is not working, the transmission will not upshift. Try operating with the auto-shift off and manually select the gears.

catmastertech, Technician
Satisfied Customers: 1831
Experience: Field service technician for CAT 19 years.
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