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Home >> Chrysler >> 2009 >> 300 Signature Series >> Repair and Diagnosis >> External Pages >> Different car >> Section 237 (Anti-Lock Brake System & Adjustable Pedals - Electrical Diagnostics) >> Electrical Diagnostics >> Abs >> DTC Troubleshooting >> C1090-Abs Brake Lamp Control Circuit Low >> Diagnostic Test

Diagnostic Test

WARNING: This page is about a different car, the 2008 Dodge Magnum, 2008 Dodge Charger, and 2008 Chrysler 300. However, it is still accessible from the selected car via links, so may be relevant.
  1. CHECK FOR DTC C1090-ABS BRAKE LAMP CONTROL CIRCUIT LOW 
    NOTE: This DTC must be active for the results of this test to be valid.

    Turn the ignition on.

    With the scan tool, record and erase DTCs.

    Start Engine.

    Apply brake pedal firmly with at least 80 bar (1160 psi.).

    With the scan tool, read DTCs.

    Does the scan tool display: C1090-ABS BRAKE LAMP CONTROL CIRCUIT LOW? 

    Yes 

    1. Go To  2.

    No 

    1. Refer to the ABS INTERMITTENT CONDITION  diagnostic procedure.
  2. CHECK CONNECTOR/TERMINAL FOR DAMAGE 
    NOTE: Check all terminals for broken, bent, pushed out, or corroded terminals.

    Turn the ignition off.

    Inspect the Anti-Lock Brake Module harness connector and the Brake Lamp Activation Relay harness connector.

    Is the Anti-Lock Brake Module or any of the connectors/terminals damaged? 

    Yes 

    1. Repair as necessary.
    2. Perform ABS VERIFICATION TEST .

    No 

    1. Go To  3.
  3. CHECK (B221) BRAKE LAMP ACTIVATION RELAY CONTROL SHORTED TO GROUND 
    Fig 1: Checking (B221) Brake Lamp Activation Relay Control Shorted To Ground
    GC0070057Courtesy of CHRYSLER LLC

    Turn the ignition off.

    Disconnect the Anti-Lock Brake Module

    Key on.

    Using a 12-volt test light connected to ground, probe the (B221) Brake Lamp Activation Relay Control Circuit at the Anti-Lock Brake Module harness connector.

    Does the test light illuminate brightly? 

    Yes 

    1. Replace the Anti-Lock Brake Module in accordance with the service information.
    2. Perform ABS VERIFICATION TEST .

    No 

    1. Go To  4.
  4. CHECK (A103) FUSED IGNITION SWITCH OUTPUT 
    Fig 2: Checking (A103) Fused Ignition Switch Output
    GC0070058Courtesy of CHRYSLER LLC

    Turn the ignition off.

    Disconnect the Brake Lamp Activation Relay.

    Key on.

    Using a 12-volt test light connected to ground, probe the (A103) Fused Ignition Switch Output Circuit at the Brake Lamp Activation Relay harness connector.

    Does the test light illuminate brightly? 

    Yes 

    1. Go To  5.

    No 

    1. Check for open Fuse, if OK repair open or short to ground in the (A103) Fused Ignition Switch Output Circuit.
    2. Perform ABS VERIFICATION TEST .
  5. BRAKE LAMP ACTIVATION RELAY 
    Fig 3: Measuring Resistance Of (B221) Brake Lamp Activation Relay Control Circuit Between Brake Lamp Activation Relay & Anti-Lock Brake Module
    GC0070059Courtesy of CHRYSLER LLC

    Turn the ignition off.

    Measure the resistance of the (B221) Brake Lamp Activation Relay Control Circuit between the Brake Lamp Activation relay and the Anti-Lock Brake Module.

    Is the resistance 5 ohms ? 

    Yes 

    1. Replace the Brake Lamp Activation Relay in accordance with the Service Information.
    2. Perform ABS VERIFICATION TEST .

    No 

    1. Repair open in the (B221) Brake Lamp Inhibit Relay Control circuit.
    2. Perform ABS VERIFICATION TEST .
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