Ben,

Connector CPS269 where all the checks will need to be made is at the DEPR which mounts to the mixer,(carb). You will need to look at the back of the connector to identify which sockets are 1 through 6. Good Luck

Thank you for the information, sir!
Would you happen to know which connectors are which?
I see no markings on any of the connectors or no identifying pin numbers.
Thank you in advance!

Ben,

These codes are for the LP system. E681 - - Electronic Pressure Regulator (EPR) Actuator Problem and E678 - Fuel Pressure at DEPR Higher Than Expected. Make sure you check each step. You may want to look at fuse 6 and 7 first before beginning. Good Luck.

Disconnect the DEPR connector CPS269 and measure voltage between socket 6 and B(-).
Is battery voltage present?
YES: Proceed to Step 2.
NO: Inspect 20A Fuse F6 and battery voltage input circuit for open or short. Inspect connectors CPS160 and
CRP15 for loose, damaged, or corroded terminals.
NOTE: Key in ON position.
2. Measure voltage between the DEPR connector CPS269, socket 3 and B(-).
Is ignition voltage present?
YES: Proceed to Step 3.
NO: Inspect 30A Start Fuse F7 and start switch for faults. Inspect ignition voltage circuit for open or short.
Inspect connectors CPS55 and CRP14 for loose, damaged, or corroded terminals.
NOTE: Key in ON position.
3. Measure voltage between the DEPR connector CPS269, socket 5 and B(-).
Is CAN HI voltage approximately 2.5 Vdc?
YES: Proceed to Step 4.
NO: Inspect CAN HI circuit for open or short. if voltage is 0 volts, the CAN HI circuit is shorted to ground or
open. If voltage is above 5 volts, the CAN HI circuit is shorted to power.
NOTE: Key in ON position.
4. Measure voltage between the DEPR connector COS269, socket 1 or 2 and B(-).
Is CAN LO voltage approximately 2.5 Vdc?
YES: Disconnect battery and proceed to Step 5.
NO: Inspect CAN LO circuit for open or short. if voltage is 0 volts, the CAN HI circuit is shorted to ground or
open. If voltage is above 5 volts, the CAN HI circuit is shorted to power.
5. Measure resistance between the DEPR connector CPS269, socket 5 and socket 1 or 2.
Is resistance 60 ± 6 ohms?
YES: No communication faults are present, connect battery and proceed to CAUSE B.
NO: If resistance is 120 ohms, the CANbus has an open circuit or a missing or damaged termination resistor.
If resistance is 0 ohms, the CANbus circuits are shorted together.
CAUSE B - DEPR FAULT
PROCEDURE OR ACTION:
1. Replace faulty DEPR.
END POSSIBLE CAUSES
ELECTRICAL SYSTEM Diagnostic Trouble Codes
Check the Service Manual section in Hypass Online for possible updates and check pertinent Gram