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B2185






B2185-IGNITION UNLOCK RUN/START CONTROL CIRCUIT HIGH





For a complete wiring diagram, refer to the Wiring Information.

- When Monitored:
With the ignition on or off and with the FCM awake.

- Set Condition:
The Front Control Module will set this DTC within 2 seconds if the ignition unlock run/start circuit voltage is not what the expected value should be.





Theory of Operation

The (F942) Fused Ignition Switch Output circuit supplies the FCM with battery power. The FCM processes the input and sends it out as the (F1) Fused Ignition Switch Output circuit to the Shift Lever assembly (3.7L or 6.1L) or the PCM (except 3.7L or 6.1L).

1. CHECK FOR ACTIVE DTC
1. With the scan tool, read the active DTCs.
2. Cycle the ignition switch from off to on, leaving the ignition on for a minimum of 10 seconds then turn the ignition off.
3. With the scan tool, read the active DTCs.

Does the scan tool display this DTC as active?

Yes

- Go To 2

No

- If the DTC is stored, check for an intermittent condition. Using the wiring diagram/schematic as a guide, visually inspect the related wiring harness connectors. Look for broken, bent, pushed out, or corroded terminals.
- Perform the BODY VERIFICATION TEST Body Verification Test.

2. DETERMINE ENGINE SIZE

Is this vehicle equipped with a 3.7L or 6.1L engine?

Yes

- Go To 3

No

- Go To 6

3. (F1) FUSED IGNITION SWITCH OUTPUT (RUN START) CIRCUIT SHORTED TO VOLTAGE




1. Disconnect the Shift Lever Assembly harness connector.
2. Cycle the ignition switch from off to on then back to off.

NOTE: The ignition switch must be in the off position when performing the following step.

3. Using a 12-volt test light connected to ground, check the (F1) Fused Ignition Switch Output (Run Start) circuit.

Does the test light illuminate brightly?

Yes

- Repair the (F1) Fused Ignition Switch Output (Run Start) circuit for a short to voltage.
- Perform the BODY VERIFICATION TEST Body Verification Test.

No

- Go To 4

4. SHIFT LEVER ASSEMBLY




1. Turn the ignition on.
2. With the test light still connected from the previous step, check the (F1) Fused Ignition Switch Output (Run Start) circuit.

Does the test light illuminate brightly?

Yes

- Replace the Shift Lever Assembly.
- Perform the BODY VERIFICATION TEST Body Verification Test.

No

- Go To 5

5. (F1) FUSED IGNITION SWITCH OUTPUT (RUN START) CIRCUIT OPEN




1. Turn the ignition off.
2. Remove the FCM from the Integrated Power Module.
3. Measure the resistance of the (F1) Fused Ignition Switch Output (Run Start) circuit between the Shift Lever Assembly and the FCM-IPM connector.

Is the resistance below 5.0 ohms?

Yes

- Inspect the wiring and connectors for damage or shorted circuits. If ok, replace and program the Front Control Module.
- Perform the BODY VERIFICATION TEST Body Verification Test.

No

- Repair the (F1) Fused Ignition Switch Output (Run Start) circuit for an open.
- Perform the BODY VERIFICATION TEST Body Verification Test.

6. (F1) FUSED IGNITION SWITCH OUTPUT (RUN START) CIRCUIT SHORTED TO VOLTAGE




1. Disconnect the Powertrain Control Module C1 harness connector.

CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install PCM Pinout Box 8815 to perform diagnosis.

2. Cycle the ignition switch from off to on then back to off.

NOTE: The ignition switch must be in the off position when performing the following step.

3. Using a 12-volt test light connected to ground, check the (F1) Fused Ignition Switch Output (Run Start) circuit.

Does the test light illuminate brightly?

Yes

- Repair the (F1) Fused Ignition Switch Output (Run Start) circuit for a short to voltage.
- Perform the BODY VERIFICATION TEST Body Verification Test.

No

- Go To 7

7. POWERTRAIN CONTROL MODULE




1. Turn the ignition on.
2. With the test light still connected from the previous step, check the (F1) Fused Ignition Switch Output (Run Start) circuit.

CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install PCM Pinout Box 8815 to perform diagnosis.

Does the test light illuminate brightly?

Yes

- Replace the Powertrain Control Module.
- Perform the BODY VERIFICATION TEST Body Verification Test.

No

- Go To 8

8. (F1) FUSED IGNITION SWITCH OUTPUT (RUN START) CIRCUIT OPEN




1. Turn the ignition off.
2. Remove the FCM from the Integrated Power Module.

CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install PCM Pinout Box 8815 to perform diagnosis.

3. Measure the resistance of the (F1) Fused Ignition Switch Output (Run Start) circuit between the Powertrain Control Module C1 connector and the FCM-IPM connector.

Is the resistance below 5.0 ohms?

Yes

- Inspect the wiring and connectors for damage or shorted circuits. If ok, replace and program the Front Control Module.
- Perform the BODY VERIFICATION TEST Body Verification Test.

No

- Repair the (F1) Fused Ignition Switch Output (Run Start) circuit for an open.
- Perform the BODY VERIFICATION TEST Body Verification Test.

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