The 691 System and "Motor Up"

1.

The control module is receiving false signals.

LED come on unexpectedly without

 

Be sure stray signals are not being introduced into the external inputs. If the

being activated.

 

gray wire is not connected to an external input, ensure that it is capped off

 

 

and not shorting to ground inadvertently. NOTE: While deactivated, occa-

 

 

sional operation of power unit and "Motor Down" LED is normal to

 

 

relieve pressure caused by thermal expansion of fluid in the power unit.

 

 

 

While the 691 System is activated,

1.

Change in temperature has caused the system to contract and reduce

the power unit and horn activate

 

brake system pressure.

intermittently.

 

The power unit runs briefly to restore brake system pressure to the original

 

 

lock-up pressure. This is considered normal operation as fluid temperature

 

 

changes.

 

 

 

 

2.

The service brake system or 691 System has air in it.

 

 

Bleed service brakes and 691 System.

 

 

 

 

3.

Hydraulic leak in either the 691 System or service brake system.

 

 

Inspect all tubing and connectors for leaks and tighten or replace as

 

 

necessary.

 

 

 

 

4.

The power unit is not functioning properly.

 

 

Replace the power unit. (No test to troubleshoot this condition).

 

 

 

NOTES

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