B2105-IGNITION UNLOCK RUN/START CONTROL CIRCUIT HIGH

For a complete wiring diagram Refer to Section 8W.

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.

Possible Causes

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

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

SHIFTER LEVER ASSEMBLY (3.7L ONLY)

POWERTRAIN CONTROL MODULE (EXCEPT 3.7L)

FRONT CONTROL MODULE

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 the PCM (except 3.7L).

Diagnostic Test

1.CHECK FOR ACTIVE DTC

Does the scan tool display this DTC as active?

Yes

Go To 2

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.

2.DETERMINE ENGINE SIZE

Is this vehicle equipped with a 3.7L engine?

Yes

Go To 3

Go To 6

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

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

Does the test light illuminate brightly?

Yes

Repair the (F1) Fused Ignition Switch Output (Run Start) circuit for a short to voltage.
Perform BODY VERIFICATION TEST – VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE)

Go To 4

4.SHIFT LEVER ASSEMBLY

Does the test light illuminate brightly?

Yes

Replace the Shift Lever Assembly in accordance with the service information.
Perform BODY VERIFICATION TEST – VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE)

Go To 5

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

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 in accordance with the service information.
Perform BODY VERIFICATION TEST – VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE)

Repair the (F1) Fused Ignition Switch Output (Run Start) circuit for an open.
Perform BODY VERIFICATION TEST – VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).

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

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 Miller Special Tool #8815 to perform diagnosis.

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

Does the test light illuminate brightly?

Yes

Repair the (F1) Fused Ignition Switch Output (Run Start) circuit for a short to voltage.
Perform BODY VERIFICATION TEST – VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE)

Go To 7

7.POWERTRAIN CONTROL MODULE

Does the test light illuminate brightly?

Yes

Replace the Powertrain Control Module in accordance with the service information.
Perform BODY VERIFICATION TEST – VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).

Go To 8

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

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 in accordance with the service information.
Perform BODY VERIFICATION TEST – VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).

Repair the (F1) Fused Ignition Switch Output (Run Start) circuit for an open.
Perform BODY VERIFICATION TEST – VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE).