DDEC III/IV Single ECM Troubleshooting

Section 17.4 Troubleshooting Flash Code 17, Relative Humidity Sensor Circuit

Section 17.4
Troubleshooting Flash Code 17, Relative Humidity Sensor Circuit

The following procedure will troubleshoot Flash Code 17, relative humidity sensor circuit failed high. ‪

Section 17.4.1
Code Check

Perform the following steps to check for codes:‪

  1. Start and run engine for 6 minutes.
  2. Plug in DDR and check for codes.
    1. If active code p 354/3 and any other codes are logged, troubleshoot the other codes first.
    2. If active code p 354/3 is logged, refer to "17.4.2 Check Connectors" .
    3. If no codes are logged, return the vehicle to service.

Section 17.4.2
Check Connectors

Perform these steps to check connectors:‪

Note: This sensor is wired via the 10–pin connector. See the wiring diagram; see Figure "Connectors" .

Click to see this graphic in a separate window

Figure 1. Connectors

  1. Check connectors for corrosion.
  2. Disconnect the connector at the RH sensor.
  3. Measure the resistance between cavities 2 and 3. See Figure "Connectors" .
    1. If measured resistance is < 5 Ω, #976 is shorted to #416. Repair the short and test.
    2. If measured resistance is > 5 Ω, go to the next step.

Section 17.4.3
Check for Open

Perform the following steps to check for open.‪

  1. Insert a jumper wire between cavity 2 and 1 of the RH sensor connector. See Figure "Connectors" .
  2. Unplug the engine side 30–pin connector.
  3. Measure the resistance between L2 and Y2.
    1. If measured resistance is < 5 Ω, replace the sensor and test.
    2. If measured resistance is > 5 Ω, either the signal return or #452 is open. Repair the open and test.

Section 17.4.4
Verify Repairs

Perform the following steps to verify repairs.‪

  1. Plug in all connectors.
  2. Clear the codes.
  3. Start and run the engine.
  4. Operate at idle and rated speed.
  5. Turn ignition OFF.
  6. Plug in DDR and read the codes.
    1. If no codes are logged, troubleshooting is complete.
    2. If any codes are logged, review this section to find the error. Then, contact Detroit Diesel Technical Services.


DDEC III/IV Single ECM Troubleshooting Guide - 6SE497
Generated on 10-13-2008

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