MBE 900 DDEC VI Troubleshooting – Section 121.2 SPN 3659/FMI 14

Section 121.2
SPN 3659/FMI 14

This diagnosis is typically the Electronic Unit Pump current is below normal or an open circuit fault.‪

Section 121.2.1
Open Circuit Check

Check as follows:‪

1. Check for multiple codes.
   1. If fault 3660/14 and 3661/14 are active in addition to 3659/14, contact the Detroit Diesel Customer Support Center (313–592–5800) for MCM replacement authorization.
   2. If only fault code 3659/14 is active, go to the next step.
2. Measure the resistance across Electronic Unit Pump #1. See Figure "Electronic Unit Pump #1" .
   

   Figure 1. Electronic Unit Pump #1

   1. If the resistance is greater than 3 Ω, replace Electronic Unit Pump #1. Refer to "121.2.1.1 Verify Repairs" .
   2. If the resistance is less than 3 Ω, go to the next step.
3. Disconnect the MCM 120–pin connector.
4. Measure the resistance between either pin of the Electronic Unit Pump #1 connector and pin 15 of the MCM 120–pin connector.
   1. If the resistance is greater than 3 Ω, repair the open between pin 15 of the 120–pin MCM connector and Electronic Unit Pump #1. Refer to "121.2.1.1 Verify Repairs" .
   2. If the resistance is less than 3 Ω, repair the open between pin 14 of the 120–pin MCM connector and Electronic Unit Pump #1. Refer to "121.2.1.1 Verify Repairs" .

Section 121.2.1.1
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.