MBE 4000 DDEC VI Troubleshooting – Section 28.4 SPN 103/FMI 4

Section 28.4
SPN 103/FMI 4

This diagnosis is typically short to ground.‪

Section 28.4.1
Short Circuit Check

Check for short as follows:‪

1. Disconnect the Turbo Speed Sensor (TSS).
2. Disconnect the 120–pin MCM connector.
3. Measure the resistance across pins 1 and 2 of the TSS connector.
   1. If the resistance is less than 5 Ω, repair the short between the 120–pin MCM connector wires 50 and 51. Refer to "28.4.2.1 Verify Repairs" .
   2. If the resistance is greater than 5 Ω, go to step 4 .
4. Measure the resistance between pin 1 of the TSS harness connector and ground.
   1. If the resistance is less than 5 Ω, repair the short between pin 1 of the TSS harness connector and ground. Refer to "28.4.2.1 Verify Repairs" .
   2. If the resistance is greater than 5 Ω, go to step 5 .
5. Measure the resistance between pin 2 of the TSS harness connector and ground.
   1. If the resistance is less than 5 Ω, repair the short between pin 2 of the TSS harness connector and ground. Refer to "28.4.2.1 Verify Repairs" .
   2. If the resistance is greater than 5 Ω, refer to "28.4.2.1 Verify Repairs" .

Section 28.4.2
Resistance Check

The resistance checks performed in the previous section indicated that you should not be getting a code. The following is a recheck before requesting a new MCM.‪

1. Reconnect all connectors. Turn ignition ON.
2. Clear codes with diagnostic tool.
3. Start and run the engine for one minute. Stop engine.
4. Recheck codes.
   1. If there are no codes, troubleshooting is finished.
   2. If code 103/4 is logged, go to step 5 .
5. Disconnect the TSS and the 120–pin MCM connector.
6. Measure the resistance across pins 1 and 2 of the TSS connector.
   1. If the resistance is less than 5 Ω, repair the short between the 120–pin MCM connector wires 50 and 51. Refer to "28.4.2.1 Verify Repairs" .
   2. If the resistance is greater than 5 Ω, go to step 7 .
7. Measure the resistance between pin 1 of the TSS harness connector and ground.
   1. If the resistance is less than 5 Ω, repair the short between pin 1 of the TSS harness connector and ground. Refer to "28.4.2.1 Verify Repairs" .
   2. If the resistance is greater than 5 Ω, go to step 8 .
8. Measure the resistance between pin 2 of the TSS harness connector and ground.
   1. If the resistance is less than 5 Ω, repair the short between pin 2 of the TSS harness connector and ground. Refer to "28.4.2.1 Verify Repairs" .
   2. If the resistance is greater than 5 Ω, contact the Detroit Diesel Customer Support Center (313–592–5800) for authorization to replace the MCM.

Section 28.4.2.1
Verify Repairs

Verify repairs as follows:‪

1. Turn ignition OFF.
2. Reconnect any electrical connections that were disconnected to perform the diagnosis.
3. Clear codes with DDDL 7.0 or latest version.
4. Start and bring engine up to operating temperature (over 140°F/60°C).
5. Verify operation is satisfactory and no warning lamps illuminate. If warning lamps illuminate, troubleshoot the codes. If assistance is required, call the Detroit Diesel Customer Support Center at 313–592–5800.