PLATE 5C0857 - Caterpillar

MID 027 CID 0444 FMI 05Conditions Which Generate This Code:
Illustration 1 g01185104
Schematic of the Start Relay (Typical Example)
The possible causes of this diagnostic code are listed:
Wire 306-GN(Green) is open.
The relay has failed.
The ECM has failed. This is unlikely.This diagnostic code is recorded when the ECM reads the current of the relay circuit as being below normal range (open circuit).Note: This procedure can cause new diagnostic codes to be recorded. Ignore these created diagnostic codes. Complete the following procedure. Then clear the created diagnostic codes.System Response:The start relay will NOT energize.Test Step 1. CHECK THE RELAY.
Turn the disconnect switch and the key start switch to the ON position. Do not start the engine. Ensure that the diagnostic code for the relay is active.
Disconnect the machine harness from the relay.
At the machine harness connector for the relay that is being tested, install a jumper wire. Install the jumper wire from contact 2 (306-GN(Green)) to contact 1 (200-BK(Black)).
Observe the status of the diagnostic code. The diagnostic code is active or the diagnostic code is NOT active. Expected Result:The status of the diagnostic code is active and the status of the diagnostic code is NOT active as the jumper is installed and then removed.Results:
YES - The circuit is correct.Repair: The relay has failed. Repeat the test step "CHECK THE RELAY" in order to verify that the relay has failed. Replace the relay.STOP
NO - The diagnostic code remains active. Proceed to test step 2.Test Step 2. CHECK THE RELAY CIRCUIT FOR AN OPEN.
The jumper that is between the signal wire and the return wire remains installed.
Turn the key start switch and the disconnect switch to the OFF position.
Disconnect the machine harness connector J2 from the ECM.
At the J2 machine harness connector for the ECM, measure the resistance from contact J2-7 for the relay to frame ground. Expected Result:There should be continuity. The resistance measures approximately 40 ohms.Results:
YES - The machine harness is correct. Proceed to test step 3.
NO - There is an open circuit in the machine harness.Repair: The open circuit is in the signal wire (306-GN(Green)) or in the ground wire. Repair the machine harness or replace the machine harness.STOPTest Step 3. CHECK IF THE DIAGNOSTIC CODE REMAINS.
The contacts of the harness connectors should be cleaned and the contacts of the harness connectors should be inspected.
Reconnect all of the harness connectors.
Turn the disconnect switch and the key start switch to the ON position.
Clear all of the inactive diagnostic codes.
Operate the machine.
Stop the machine and place the parking brake switch in the ON position.
Observe the status of the diagnostic code. The diagnostic code is active or the diagnostic code is NOT active. Expected Result:The diagnostic code is NO longer active.Results:
YES - The diagnostic code is NO longer active. The diagnostic code does not exist at this time. The initial diagnostic code was probably caused by a poor electrical connection or a short at one of the harness connectors that was disconnected and reconnected. Resume normal machine operation.STOP
NO - The diagnostic code has not