722 TRANS Light

[Atilathehun99]

Was cleaning off the driveway when I noticed the TRANS (hydraulic system) light come on. Stopped and checked fluid level and had to add between 1 and 2 gallons (on a 13-gallon system) to get it back up to high-high (top level check plug) level. Light still came on when running. Next I changed both hydraulic filters but the light still is on. NOTE: This unit does not have the "bronze" filter often mentioned on this forum. I had to run the unit a couple of minutes to move it and all systems are fully operative. Another thing when the TRANS warning light wire is pulled off the sensor the light does go out. Thanks in advance for any ideas or comments.

 

[Tazza]

It's possible the issue is the sender, they do go bad.
Just how cold was it? When cold, the oil can get thicker, so it's harder to pump till it gets warm.

 

[Atilathehun99]

It's possible the issue is the sender, they do go bad.
Just how cold was it? When cold, the oil can get thicker, so it's harder to pump till it gets warm.

It was about freezing + or - a couple of degrees. It's been just fine at lower outside temps. I was also wondering about the sending unit. Is there a way to check it w/out just replacing it? The other thing I wondered about is the check by-pass valve. If this were stuck could it cause the light to come on indicating low pressure?

 

[Tazza]

It was about freezing + or - a couple of degrees. It's been just fine at lower outside temps. I was also wondering about the sending unit. Is there a way to check it w/out just replacing it? The other thing I wondered about is the check by-pass valve. If this were stuck could it cause the light to come on indicating low pressure?

If you remove the sender and install a pressure gauge, it will tell you if your charge pressure is in range or not. It should be about 90 PSI from memory.
If it is right, the sender isn't measuring correctly.

 

[Atilathehun99]

If you remove the sender and install a pressure gauge, it will tell you if your charge pressure is in range or not. It should be about 90 PSI from memory.
If it is right, the sender isn't measuring correctly.

UPDATE: I took Tazza's advice (thanks) and installed a gauge. The system was at 70 psi at full throttle which is within the 55 psi to 80 psi range noted in the service manual for the by-pass valve. The local Bobcat service manager confirmed that 70 psi at the filter was acceptable. I've ordered a new sending unit.