Tweco Troubleshooting Power Supply - Manual (Page 35)

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When there is a communication error it will be displayed but once it has recovered the
display will show what the error was by displaying:
^E4 – Low level CAN bus error where the CCM did not acknowledge receiving a
message from the Gas Control.
^E5 – Low level CAN bus error where the bus is off.
^E6 – CAN bus communication (the fiber optic) has timed out.
Coolant System Codes
4-1
Coolant Level
Coolant level SW, in the top of the coolant tank, is normally closed, opens
when level is above approximately ½ full. Signal from SW goes to CN14 on
PCB5. Output of PCB5 is on CN11, 34 ckt. ribbon cable that goes to CCM J36.
Possible causes of low coolant code (other than low coolant) are:
• Defective level SW
• Wiring
• PCB5
• CCM
Defective level SW – Disconnect connector at level SW. If the low level code
goes away the level sensor is defective. You can operate with the sensor
disconnected but until you can replace it but won’t be warned if the coolant is
actually low.
PCB5 – Level SW connects to PCB5 at CN14 pins 1 (signal) & 2 (gnd). Remove
CN14, if the 4-1 code goes away problem is in wiring between level SW and
connector. If code remains, Measure output of PCB5 on pin 10 of 34 ckt. ribbon
cable CN11/J36. If less than 1V PCB5 is faulty or ribbon cable pin 10 is shorted
to pin 9 or 11. Otherwise replace CCM.
If coolant really is low but system fails to detect it: Causes can be all of the above
plus connector on Level SW or CN14 on PCB5 disconnected.
When coolant is low a resistance reading between the two pins of level switch
connector should be a short. If open switch is defective.
4-2
Low or No Coolant Flow.
Coolant flow is detected by coolant sensor F1 located in the return plumbing
between the radiator and the upper inlet of the coolant tank. It is a turbine type
that puts out a pulse train whose frequency is relative to the flow. Frequency is
752 pulses per minute per liter. When not cutting, if flow is less 0.7 gal/min for
15 seconds it generates a fault.
When cutting, if flow is between 0.35 and 0.7 gal/min, for more than 3 sec or
less than 0.35 gal/min for any time at all it generates a fault.
Coolant sensor received +5V (pin 1) and gnd (pin 3) from CN13 on PCB5.
Coolant Flow signal (frequency) is on pin 2. Signal is buffered on PCB5 and
passed to CCM on pin 6 of the 34 ckt. ribbon cable, CN11 to J36. Signal common