BREAKER AS-CIRCUIT 9G9487 - Caterpillar

System Operation Description:The diagnostic code 336-02 is generated when the Electronic Control Module (ECM) detects a difference in potential between the start/run/stop inputs to the ECM. The two inputs are in an open state until the "CR" relay is energized. When the "CR" relay is energized, the start/run/stop inputs to the ECM are connected to the digital return. A broken wire or an improper connection at one of the connectors will cause the ECM to generate this code.
Illustration 1 g01023335
Typical circuit with EMS IITest Step 1. Check for an Open in the Circuit.
Turn the ECS to the OFF position.
Turn the battery disconnect switch to the OFF position.
Disconnect ECM connector J1/P1.
Measure the resistance at the ECM connector P1 between wire F717-YL in pin P-14 and wire F716-WH in pin P-08.Expected Result:The resistance measures less than 5 Ohms.Results:
OK - The resistance measures less than 5 Ohms. Proceed to Test Step 2.
Not OK - The resistance measures more than 5 Ohms.Repair: Check each individual wire for damage. Check the connections between the engine connector and the number two contacts of the "CR" relay. Repair the wires and/or connectors. Stop.Test Step 2. Check for a Short in the Circuit.
Disconnect the "D.C. Connector No. 1 (BK)" in the panel for the EMS II.
Measure the resistance at the ECM connector P1 between wire F717-YL in pin P-14 and engine ground.
Measure the resistance at the ECM connector P1 between wire F716-WH in pin P-08 and engine ground.Expected Result:The resistance measures more than 20000 Ohms.Results:
OK - The resistance measures more than 20000 Ohms.Repair: Check the wires from the "D.C. Connector No. 1 (BK)" to the number two contacts of the "CR" relay. Repair the wires. Stop.
Not OK - The resistance measures less than 20000 Ohms.Repair: There is a short in one of the wires. Repair the wire. Stop.