MBE 900 DDEC VI Troubleshooting – Section 96.1 SPN 2629/FMI 3

Section 96.1
SPN 2629/FMI 3

This condition is typically open circuit.‪

Section 96.1.1
Open Circuit Check

Check as follows:‪

1. Disconnect the TCO Sensor. See Figure "TCO Sensor" .
   

   Figure 1. TCO Sensor

2. Turn the ignition ON (key ON, engine OFF).
3. Measure the resistance across pins 1 and 2 of the TCO Sensor.
   1. If the resistance is not within the range listed in Table "Turbo Compressor Outlet Temperature Sensor Resistance" , replace the TCO Sensor. Refer to "96.1.1.1 Verify Repairs" .
   2. If the resistance is within the range listed in Table "Turbo Compressor Outlet Temperature Sensor Resistance" , go to step 4 .

   Temperature (°F)‪	Temperature (°C)‪	Maximum Resistance (KΩ)‪	Minimum Resistance (KΩ)‪
   32‪	0‪	1053.00‪	634.00‪
   50‪	10‪	601.75‪	367.98‪
   68‪	20‪	357.27‪	224.97‪
   86‪	30‪	219.54‪	142.08‪
   104‪	40‪	139.17‪	92.40‪
   122‪	50‪	90.75‪	61.72‪
   140‪	60‪	60.72‪	42.23‪
   158‪	70‪	41.58‪	29.55‪
   176‪	80‪	29.10‪	21.09‪
   194‪	90‪	20.77‪	15.34‪

   Table 1. Turbo Compressor Outlet Temperature Sensor Resistance
4. Turn the ignition ON (key ON, engine OFF).
5. Measure the voltage between pins 1 and 2 of the TCO Sensor harness connector.
   1. If the voltage is between 2.75 and 3.25 volts, refer to "96.1.1.1 Verify Repairs" .
   2. If the voltage is less than 2.75 volts, go to step 6 .
6. Measure the voltage between pin 2 of the TCO Sensor harness connector and ground.
   1. If the voltage is between 2.75 and 3.25 volts, repair the open circuit between pin 1 of the TCO Sensor harness connector and pin 52 of the 120–pin MCM connector. Refer to "96.1.1.1 Verify Repairs" .
   2. If the voltage is less than 2.75 volts, repair the open circuit between pin 2 of the TCO Sensor harness connector and pin 112 of the 120–pin MCM connector. Refer to "96.1.1.1 Verify Repairs" .

Section 96.1.1.1
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.