Wiring Harness Conditions on the 2.8L Diesel Engine

A number of conditions regarding engine performance and air conditioning operation on some 2016-2021 Colorado and Canyon models equipped with the 2.8L diesel engine (RPO LWN) may be due to the engine wiring harness rubbing on other components. These conditions may include the air conditioning not cooling or blowing hot air, a fluctuating engine oil pressure gauge, several Diesel Exhaust Fluid (DEF) messages displayed, an engine no start or misfire, and several illuminated warning lamps.

Complete the diagnostic instructions in the appropriate Service Information for any symptoms or DTCs found. If the diagnosis does not lead to a resolution, check for chafing of the engine wiring harness or connector concerns in the following areas, perform any necessary wiring repairs and reroute the harness.

 

Air Conditioning

A wiring harness concern (Fig. 18) with the air conditioning (A/C) compressor, A/C compressor suction and discharge line manifold, A/C line and A/C compressor clutch may cause:

  • The Check Engine light to illuminate and DIC messages to be displayed.
  • The engine to run rough or a possible extended crank or crank/no start.
  • The 4WD warning lamp or StabiliTrak warning lamp to illuminate.
  • The oil pressure gauge to read erratically or show no oil pressure.
  • The A/C to not cool or blow hot air.
  • An open fuse in the Underhood Bussed Electrical Center (UBEC).

 

Fig. 18

 

Serpentine Belt

The fan clutch wiring harness support bracket (Fig. 19) may be out position and allow the harness to rub on the belt, which may cause:

  • An engine crank/no start condition or the engine to run rough or misfire.
  • The Check Engine light or other warning lamps to illuminate, such as the 4WD warning lamp or StabiliTrak warning lamp.
  • The A/C to not cool or blow hot air.

 

Fig. 19

 

Rear of Engine

TIP: Refer to Bulletin #16-NA-081 for additional information on harness damage on the exhaust heat shield.

A wiring harness concern near the exhaust heat shield at the right rear of the engine (Fig. 20) may cause:

  • The 4WD warning lamp or StabiliTrak warning lamp to illuminate.
  • The Check Engine light to illuminate.
  • A Reduced Power message on the DIC.
  • An open fuse in the UBEC.

 

Fig. 20

 

Transmission Bell Housing

A wiring harness concern with the transmission bell housing bolt/stud (Fig. 21) may cause:

  • The 4WD warning lamp or StabiliTrak warning lamp to illuminate.
  • The Check Engine light to illuminate.

 

Fig. 21

 

Coolant Pipe

A wiring concern near the coolant pipe and clamp tabs between the engine and cowl (Fig. 22) may cause:

  • The 4WD warning lamp or StabiliTrak warning lamp to illuminate.
  • The Check Engine light to illuminate.

 

Fig. 22

 

Brake Fluid Level Switch

A wiring harness concern (Fig. 23) in this area may cause:

  • The Check Engine light and service brake lamp to illuminate.
  • A Low Brake Fluid message on the DIC.

 

Fig. 23

 

Transfer Case Encoder Motor

A wiring harness concern (Fig. 24) in this area may cause:

  • The Check Engine light or other warning lamps to illuminate.

 

Fig. 24

 

Turbocharger Vane Position Actuator

Loose terminals or a connector not fully seated at the turbocharger vane position actuator (Fig. 25) may cause:

  • The Check Engine light or other warning lamps to illuminate.
  • A reduced power message on the DIC and a low power condition.

 

Fig. 25

 

For additional information, refer to #PIP5416D.

 

– Thanks to John Stempnik

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