DDEC III/IV Single ECM Troubleshooting – Section 10.4 Check Engine Light and Stop Engine Light Fault

Section 10.4
Check Engine Light and Stop Engine Light Fault

The following steps will troubleshoot a fault with the check engine or stop engine lights. These lights are used to alert the operator of engine faults; flash any trouble codes stored in the ECM; and illuminate for five seconds and then go out during a start sequence, as a bulb check.‪

Section 10.4.1
Determine Fault

Perform the following to determine fault:‪

1. If the CEL or SEL is always on, refer to "10.4.2 Display ECM Light Status" .
2. If the CEL or SEL never lights, refer to "10.4.5 Activate Light With Diagnostic Data Reader" .

Section 10.4.2
Display ECM Light Status

Perform the following steps to display light status:‪

1. While the light is lit, plug in the DDR (ignition ON).
2. Select switch light status.
3. View the displayed status for the problem light.
   1. If status reads OFF, refer to "10.4.4 Check for Grounded Wire" .
   2. If status reads ON, refer to "10.4.3 Determine Reason for ECM Request" .

Section 10.4.3
Determine Reason for ECM Request

Perform the following steps to determine the reason the ECM is requesting the light to be ON:‪

1. Verify the diagnostic request is not ON.
   1. If the diagnostic request is ON, refer to "10.10 Engine Brake Inoperative" .
   2. If the diagnostic request is not ON, refer to "9.1 First Step for Diagnosing a Fault Within the DDEC System" , (troubleshoot code).

Section 10.4.4
Check for Grounded Wire

Perform the following steps to check for a grounded wire:‪

1. Turn ignition OFF.
2. Unplug VIH 30-pin connector.
3. Turn ignition ON.
   1. If the light stays on, drive (#509 or #419) wire is shorted to the ground. Repair or replace the wire. Refer to "10.4.9 Verify Repairs" .
   2. If the light goes off, clean the connectors of the VIH 30-pin and assemble again. Then, refer to "10.4.9 Verify Repairs" .

Section 10.4.5
Activate Light With Diagnostic Data Reader

Perform the following steps to activate the light with the DDR:‪

1. Turn ignition ON.
2. Plug in DDR.
3. Select Activate Outputs.
4. Activate affected light; watch status.
   1. If the light stays off. Refer to "10.4.6 Check Bulb" .
   2. If the light illuminates, the problem no longer exists. Refer to DDEC III Application and Installation manual, 7SA800, to review the light operation.

Section 10.4.6
Check Bulb

Perform the following steps to check the bulb:‪

1. Turn ignition OFF.
2. Refer to OEM recommendations for checking bulb.
   1. If the bulb is bad, replace the bulb and refer to "10.4.9 Verify Repairs" .
   2. If the bulb is okay, refer to "10.4.7 Check for Voltage Supply" .

Section 10.4.7
Check for Voltage Supply

Perform the following steps to check the voltage supply:‪

1. Disconnect the power supply to the light.
2. Turn ignition ON.
3. Measure voltage between the removed connection and battery ground.
   1. If the voltage is correct based on the system of the vehicle (12V/24V), refer to "10.4.8 Check for Open Output Wire" .
   2. If the voltage is too low to expect the bulb to light, refer to the OEM recommendations to resolve the problem. Refer to "10.4.9 Verify Repairs" .

Section 10.4.8
Check for Open Output Wire

Perform the following steps to check for an open output wire:‪

1. Measure the resistance between the ground side of the connector of the light and the battery ground.
   1. If the measured resistance is 45,000 to 48,000 Ω, clean the connections. Refer to "10.4.9 Verify Repairs" .
   2. If the measured resistance is less than 45,000 Ω or greater than 48,000 Ω, the wire is shorted to voltage, or is opened. Repair wire. Refer to "10.4.9 Verify Repairs" .

Section 10.4.9
Verify Repairs

Perform the following steps to verify repairs.‪

1. Ensure all removed connections are installed.
2. Turn ignition ON.
   1. If the light comes on for five seconds, then goes out, troubleshooting is complete.
   2. If the light comes on and stays on, refer to "10.4.1 Determine Fault" .
   3. If the light does not turn on, all troubleshooting is complete. Review this section and contact Detroit Diesel Technical Service.