DDEC III/IV Single ECM Troubleshooting – Section 46.3 Troubleshooting Flash Code 46

Section 46.3
Troubleshooting Flash Code 46

The following procedure will troubleshoot Flash Code 46.‪

Section 46.3.1
Battery Check

Perform the following steps to check the battery.‪

1. Start and run the engine for one minute.
2. Measure voltage on battery + terminal (red lead) to battery - terminal (black lead). Recommended fuse applications are listed in Table "Fuse Size Recommendations" . Power harness length criteria is listed in Table "Maximum Resistance vs Power Harness Length" .
   1. If the engine does not start, inspect the battery and charging/starting system, and proceed if okay. Refer to "9.1 First Step for Diagnosing a Fault Within the DDEC System" .
   2. If the engine does start and the voltage measurement is less than or equal to 10.0 volts, service the discharged battery and charging/starting system.
   3. If the engine does start and the voltage measurement is greater than 10.0 volts, refer to "46.3.2 Voltage Check at ECM" .

   Number of Cylinders ‪	Dual Fuse or Circuit Breaker Size ‪	Single Fuse or Circuit Breaker Size ‪
   6‪	2 @ 15 amp‪	1 @ 30 amp‪
   8‪	2 @ 20 amp‪	1 @ 40 amp‪
   12‪	4 @ 15 amp‪	2 @ 30 amp‪
   16‪	4 @ 20 amp‪	2 @ 40 amp‪
   20‪	4 @ 15 amp; 2 @ 20 amp‪	2 @ 30 amp; 1 @ 40 amp‪

   Table 1. Fuse Size Recommendations

   Length from ECM to Battery or Bus Bar (ft) *‪	Minimum Wire Size (Ga) *‪	Total Resistance of Maximum Length (m Ω ) *‪	Length from ECM to Battery or Bus Bar (m) †‪	Minimum Wire Size (Ga) †‪	Total Resistance of Maximum Length (m Ω ) †‪
   0 to 28 ‡‪	12‪	24.8‪	0 to 6 ‡‪	2.5‪	22.8‪
   28 to 44 ‡‪	10‪	24.57‪	6 to 10 ‡‪	4‪	23.55‪
   44 to 70 ‡‪	8‪	24.58‪	10 to 14 ‡‪	6‪	21.98‪
   70 to 110 ‡‪	6‪	24.7‪	14 to 26 ‡‪	10‪	23.66‪
   110 to 178 ‡‪	4‪	25.0‪	26 to 40 ‡‪	16‪	23.2‪
   0 to 14 §‪	12‪	24.8‪	0 to 3 §‪	2.5‪	22.8‪
   14 to 22 §‪	10‪	24.57‪	3 to 5 §‪	4‪	23.55‪
   22 to 35 §‪	8‪	24.58‪	5 to 7 §‪	6‪	21.98‪
   35 to 55 §‪	6‪	24.7‪	7 to 13 §‪	10‪	23.66‪
   55 to 89 §‪	4‪	25.0‪	13 to 20 §‪	16‪	23.2‪

   Table 2. Maximum Resistance vs Power Harness Length

   Note: * United States

   Note: † International

   Note: ‡ Dual Fuse

   Note: § Single Fuse

Section 46.3.2
Voltage Check at ECM

Perform the following steps to check voltage at the ECM.‪

1. Keep engine running.
2. Select ECM INPUT VOLT on DDR.
3. Observe ECM voltage reading on DDR.
   1. If the voltage measurement is less than or equal to 10.0 volts, refer to "46.3.3 Voltage Check at ECM Via Volt-Ohm Meter" .
   2. If the voltage measurement is greater than 10.0 volts, refer to "46.3.5 Ground Check at ECM" .

Section 46.3.3
Voltage Check at ECM Via Volt-Ohm Meter

Perform the following steps to check voltage at the ECM.‪

1. Turn the vehicle ignition OFF.
2. Disconnect 5-way power harness connector at the ECM.
3. Measure voltage from socket A and C (red lead) of 5-way power harness connector and a good battery ground (black lead). Don't use line (#151) as a ground reference. For 5-way ECM power harness connector, see Figure "5-Way ECM Power Connector" . For power harness schematic, see Figure "Power Harness" .
   1. If the voltage measurement is less than or equal to 11.5 volts, refer to "46.3.4 Check for Bad Battery + Line" .
   2. If the voltage measurement is greater than 11.5 volts, refer to "46.3.5 Ground Check at ECM" .
   

   Figure 1. 5-Way ECM Power Connector

   

   Figure 2. Power Harness

Section 46.3.4
Check for Bad Battery + Line

Perform the following steps to check for a bad battery + line.‪

1. Remove fuse(s) to the ECM.
2. Measure voltage at socket A of one fuseholder (red lead) to a good ground (black lead). For 5-way ECM power harness, see Figure "5-Way ECM Power Harness" .
3. Repeat voltage measurement at other fuseholder.
   1. If the voltage measurement is greater than 11.5 volts on both readings, the battery + line between the fuseholder and ECM has an open, or the ECM power connector has a corroded connection. Repair the problem. Refer to "46.3.8 Verify Repairs" .
   2. If the voltage measurement is less than or equal to 11.5 volts on either reading, the battery + line near the battery is open, or a corroded connection exists at battery + terminal. Repair the problem. Refer to "46.3.8 Verify Repairs" .
   

   Figure 3. 5-Way ECM Power Harness

Section 46.3.5
Ground Check at ECM

Perform the following steps to check the ground at the ECM.‪

1. Disconnect the 5-way power harness connectors at the ECM. For 5-way ECM power harness, see Figure "5-Way ECM Power Harness" .
2. Measure voltage on socket A (red lead) to socket D (black lead) and socket C of 5-way power harness connector (red lead) to socket E, (black lead).
   1. If voltage measurement is greater than 11.5 volts on either reading, refer to "46.3.6 Check ECM Connectors" .
   2. If the voltage measurement is less than or equal to 11.5 volts on either reading, the ground wire (#150) is open or has a corroded connection. Repair ground wire, and refer to "46.3.8 Verify Repairs" .

Section 46.3.6
Check ECM Connectors

Perform the following steps to check ECM connectors.‪

1. Check terminals at the ECM 5-way power harness connector (both ECM and harness side) for damage; bent, corroded, and unseated pins or sockets.
   1. If terminals and connector are damaged, repair them. Refer to "46.3.8 Verify Repairs" .
   2. If terminals and connector are not damaged, verify the power and ground are wired directly to the battery. Refer to "46.3.7 Code Check" .

Section 46.3.7
Code Check

Perform the following steps to check for codes.‪

1. Install the vehicle interface module.
2. Turn ignition ON; plug in DDR.
3. Check for codes.
   1. If code reoccurs, install test ECM, then refer to "46.3.8 Verify Repairs" .
   2. If code does not reoccur, check power harness wires for breaks, abrasions, etc. Then refer to "46.3.8 Verify Repairs" .

Section 46.3.8
Verify Repairs

Perform the following steps to verify repairs.‪

1. Turn vehicle ignition OFF.
2. Reconnect all connectors.
3. Turn ignition ON.
4. Clear codes with DDR.
5. Start and run the engine for one minute.
6. Stop engine.
7. Check DDR for codes.
   1. If no codes are displayed, troubleshooting is complete.
   2. If code 168/1 is not logged, and other codes are logged, refer to "9.1 First Step for Diagnosing a Fault Within the DDEC System" .
   3. If code 168/1 is logged, and other codes are logged, all system diagnostics are complete. To troubleshoot the error, refer to "46.3.1 Battery Check" .