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Home >> Chrysler >> 2011 >> 300 C, RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 99 (6.7L Diesel - DTCS - P1192 To P21C3 - 3500 Cab & Chassis) >> Diagnosis and Testing >> P21C3-(Diesel Exhaust Fluid) REDUCTANT Line Heater Relay Control Circuit Low >> Testing >> Diagnostic Test

Diagnostic Test

WARNING: This page is about a different car, the 2011 RAM Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.
  1. ACTIVE DTC 
    1. Turn the ignition on.
    2. With the scan tool, View DTCs.

      Is the DTC active?

      Yes 

      • Go To  2.

      No 

  2. CHECK THE DEF LINE HEATER RELAY 
    1. With the scan tool, Erase DTCs.
    2. Turn the ignition off.
    3. Replace the DEF Line Heater Relay with a known good relay.
    4. Turn the ignition on.
    5. With the scan tool, navigate to Actuator Tests and actuate the Line Heater Relay.
    6. With the scan tool, View DTCs.

      Did the DTC return?

      Yes 

      • Go To  3.

      No 

  3. CHECK THE (K475) DEF LINE HEATER RELAY SIGNAL CIRCUIT FOR A SHORT TO GROUND 
    Fig 1: Checking DEF Line Heater Relay Signal Circuit For A Short To Ground
    GC0148891Courtesy of CHRYSLER LLC
    1. Stop actuation of the Line Heater Relay.
    2. Turn the ignition off.
    3. Remove the DEF Line Heater Relay.
    4. Disconnect the DEF Dosing Control Unit C2 harness connector.
    5. Measure the resistance between ground and the (K475) DEF Line Heater Relay Signal circuit at the Line Heater Relay, terminal 86.

      Is the resistance above 10k Ohms?

      Yes 

      • Go To  4.

      No 

      • Repair the (K475) DEF Line Heater Relay Signal circuit for a short to ground.
      • Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Refer to POWERTRAIN VERIFICATION TEST - 6.7L .
  4. CHECK THE (K429) DEF LINE HEATER RELAY CONTROL CIRCUIT FOR A SHORT TO GROUND 
    Fig 2: Checking DEF Line Heater Relay Control Circuit For A Short To Ground
    GC0148890Courtesy of CHRYSLER LLC
    1. Measure the resistance between ground and the (K429) DEF Line Heater Relay Control circuit between the Line Heater Relay, terminal 85.

      Is the resistance above 10k Ohms?

      Yes 

      No 

      • Repair the (K429) DEF Line Heater Relay Control circuit for a short to ground.
      • Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Refer to POWERTRAIN VERIFICATION TEST - 6.7L .