Detroit Diesel Troubleshooting Diagrams

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Series 60 DDEC II Engine Sensor Harness

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An improved vehicle engine sensor harness which virtually eliminates the potential for wire chafing damage has replaced the former harness on all Detroit Diesel Series 60 DDEC II engines. This change took effect approximately October 30, 1992

Detroit Diesel has found instances of chafing on the sensor connector harness (part number 8929468) used on DDEC II engines. The chafing can occur at the end of the plastic tee-coupling where the wires from the 30-way connector enter the coupling.  The chafing results from the absence of abrasion-resistant, convoluted tubing around the wires. Installing convoluted tubing is impractical due to the shortness of the wires at this point. With no abrasion-resistant material surrounding the wires, the rough plastic ridges inside the leg of the tee-coupling can cut through the wire coatings, exposing the wires to moisture and potential shorting. Shorting can result in the logging of false DDEC trouble codes. ‪

Series 60 DDEC II Engine Sensor Harness Series 60 DDEC II Engine Sensor Harness

Written by sam

October 19th, 2011 at 3:35 am

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Series 60 DDEC III/IV Engine Sensor Harness

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The DDEC III/IV engine sensor harness for vehicle engines was originally equipped with five metal retaining clips and was secured to the engine cylinder block with bolts. Effective with engines built in May of 1995, three of the metal clips were replaced by three plastic push-in clips.

Due to a hardware change made in October of 1995 to the DDEC ® III ECM, a path to ground can arise during ECM powerdown which may allow unintended engine cranking. ‪

Unintended engine cranking can occur if all of the following conditions exist: ‪

  • The engine has an ECM manufactured between October of 1995 and September of 1996.
  • The engine is equipped with the Optimized Idle feature.
  • The ignition remains turned on while battery power is removed from the ECM during servicing.

Note: This condition will not occur on engines manufactured after September of 1996.

To address this concern and eliminate the potential for unintended engine cranking under the conditions listed above, an Optimized Idle Starter Relay Harness Overlay Service Kit was released for engines with ECM’s manufactured between October of 1995 and September of 1996. ‪

Written by sam

October 19th, 2011 at 3:32 am

Posted in Electrical

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