769D won’t shift out of neutral. When you put it in Reverse it wants to go forward and the gauge shows neutral even though the back up alarm goes off. When you shift to 1st it shows neutral on the gauge. Have new shift sensor and transmission sensor. Up and down solenoids good too. Transmission speed sensor good so is the transmission computer behind cab. Anyone know what else could cause this symptom? Can the neutralizer switch cause this? Will let y’all know what I find.
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769D won’t shift.
- Thread starter Lewis12
- Start date
kshansen
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As always, at least with Cat equipment, a full serial number would be of great help.
Where I worked at my plant we had a 769D and when another plant had a 769D that went over a bank and was damaged to the point it was not worth fixing. So they sent me to that other plant to salvage some parts for ours and to my surprise the two trucks were very different even to the point of where the hydraulic and fuel tanks were located. So I'm very aware that just because yor truck has 769D decals on the side it would be a waste of my time making any suggestions.
Kind of like me saying I have an F150 that is not shifting right What is wrong? By the way they have been building trucks called the F150 for a little over 40 years!
kshansen
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In addition to what I wrote above I will say that depending on the vintage of the 769D there may be a manual shift option that can be accessed right at the transmission. This if your truck is of that design lets you directly control the transmission to eliminated the electronics from the process. Also would give you a means to move truck if need be.
Yup this one has that option to shift the transmission manually. So if you upshift the transmission manually like to 7th grear it should up shift automatically or does this only put it in the gear that is manually selected? Also am gunna pull the scavenge screen from the torque converter. Is there any other method to troubleshoot a bad torque converter? I replaced the filter for the torque converter but didn’t notice anything wrong. Also changed the tranny filter since it’s next to it. Didn’t replace the parking brake filter yet but I think some of the torque converter valves get pressurized oil from this filter. Thinking filter might need changing or the screen might show something. Any suggestions? Will post any findings.
Mark250
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hi Lewis ,serial number please, assuming you have checked the basics I would isolate the transmission hydraulic system from transmission electrical system.
you can operate the transmission manually.
disconnect the lockup ,downshift and upshift solenoid electrical connectors.
remove the plug on the transmission case ,on the opposite side of the shift card.
apply park brake and service brakes (front brakes as well)
place a 1/4 inch socket extension bar into the hole that plug was removed from and into the end of the selector shaft, rotate the shift lever in the clockwise direction to place transmission in neutral
start the machine and manually rotate the shift lever through all the gears
check that engagement takes place
CAUTION MACHINE CAN MOVE DURING THIS TEST
As a quick check of hydraulic operation refit all electrical connections . rotate shift lever anticlockwise and start engine. the shift lever should rotate back to neutral position
Further testing requires the use of gauges
if this is ok we can move on to the electrical system
A couple of things to check first
it has been known for the locating pins in the shift shaft and rotary actuator
to break and come loose .remove the shift card and the flexible shaft place a screwdriver into the slot that the flexible shaft came out of and try and turn with moderate pressure there should be no movement
like wise on the detent end (where the 1/4 inch drive is) there should be no loose movement
Mark
you can operate the transmission manually.
disconnect the lockup ,downshift and upshift solenoid electrical connectors.
remove the plug on the transmission case ,on the opposite side of the shift card.
apply park brake and service brakes (front brakes as well)
place a 1/4 inch socket extension bar into the hole that plug was removed from and into the end of the selector shaft, rotate the shift lever in the clockwise direction to place transmission in neutral
start the machine and manually rotate the shift lever through all the gears
check that engagement takes place
CAUTION MACHINE CAN MOVE DURING THIS TEST
As a quick check of hydraulic operation refit all electrical connections . rotate shift lever anticlockwise and start engine. the shift lever should rotate back to neutral position
Further testing requires the use of gauges
if this is ok we can move on to the electrical system
A couple of things to check first
it has been known for the locating pins in the shift shaft and rotary actuator
to break and come loose .remove the shift card and the flexible shaft place a screwdriver into the slot that the flexible shaft came out of and try and turn with moderate pressure there should be no movement
like wise on the detent end (where the 1/4 inch drive is) there should be no loose movement
Mark
Last edited:
kshansen
Senior Member
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- Mar 11, 2012
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- Central New York, USA
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- Retired Mechanic in Stone Quarry
Glad to hear you found the problem!