MBE 900 DDEC VI Troubleshooting – Section 25.2 SPN 91/FMI 3

Section 25.2
SPN 91/FMI 3

The typical diagnosis for this fault is high voltage.‪

Section 25.2.1
High Voltage Check

Check as follows:‪

1. Disconnect the Accelerator Pedal (AP).
2. Turn the ignition ON (key ON, engine OFF).
3. Measure the voltage between pins 1 and 3 of the AP harness connector.
   1. If the voltage is between 4.5 and 5.5 volts, go to step 5 .
   2. If the voltage is less than 4.5, .
4. Measure the voltage between pins 1 of the AP harness connector and ground.
   1. If the voltage is between 4.5 and 5.5 volts, repair the open circuit between pin 3 of the AP harness connector and pin 4 of the CPC #1 connector. See Figure "Accelerator Pedal Assembly Installation" . Refer to "25.2.1.1 Verify Repairs" .
   2. If the voltage is less than 4.5, repair the open circuit between pin 1 of the AP harness connector and pin 8 of the CPC #1 connector. See Figure "Accelerator Pedal Assembly Installation" . Refer to "25.2.1.1 Verify Repairs" .
   

   Figure 1. Accelerator Pedal Assembly Installation

5. Turn the ignition OFF.
6. Disconnect the CPC #1 connector.
7. Measure the resistance between pin 2 of the AP harness connector and pin 7 of the CPC #1 connector.
   1. Measure the resistance between pin 2 of the AP harness connector and pin 7 of the CPC #1 connector. Refer to "25.2.1.1 Verify Repairs" .
   2. If the resistance is less than 3 Ω, replace the Accelerator Pedal. Refer to "25.2.1.1 Verify Repairs" .

Section 25.2.1.1
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.