B2104-IGNITION UNLOCK RUN/START CONTROL CIRCUIT LOW

For a complete wiring diagram Refer to Section 8W.

When Monitored:
With the ignition on.
Set Condition:
The Front Control Module will set this DTC within 500ms if the (F1) fused ignition switch output circuit voltage is less than the expected value.

Possible Causes

(F1) FUSED IGNITION SWITCH OUTPUT CIRCUIT SHORTED TO GROUND

SHIFT LEVER ASSEMBLY (3.7L ONLY)

POWERTRAIN CONTROL MODULE (EXCEPT 3.7L)

INTEGRATED POWER MODULE

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

With the scan tool, read the active DTC's.
Cycle the ignition switch from off to on, leaving the ignition on for a minimum of 10 seconds.
With the scan tool, read the active DTC's.

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. SHIFT LEVER ASSEMBLY

With the scan tool, erase the FCM DTC's.
Turn the ignition off.
Disconnect the Shift Lever Assembly harness connector.
Cycle the ignition switch from off to on, leaving the ignition on for a minimum of 10 seconds.
With the scan tool, read the active FCM DTC's.

Does the scan tool display this DTC as active?

Yes

Go To 4

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) .

4. (F1) FUSED IGNITION SWITCH OUTPUT WIRE SHORT TO GROUND

Turn the ignition off.
Disconnect the Integrated Power Module C1 harness connector.
Measure the resistance between ground and the (F1) Fused Ignition Switch Output circuit in the IPM C1 connector.

Is the resistance below 1000.0 ohms?

No

Go To 5

Yes

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

5. INTEGRATED POWER MODULE SHORTED

Remove the FCM from the Integrated Power Module.
Measure the resistance between ground and the (F1) Fused Ignition Switch Output circuit in the Front Control Module IPM connector.

Is the resistance below 1000.0 ohms?

Yes

Replace the Integrated Power Module in accordance with service information.

Perform BODY VERIFICATION TEST – VER 1. (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - STANDARD PROCEDURE)

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)

6. POWERTRAIN CONTROL MODULE

With the scan tool, erase the FCM DTC's.
Turn the ignition off.
Disconnect the Powertrain Control Module C1 connector.
Cycle the ignition switch from off to on, leaving the ignition on for a minimum of 10 seconds.
With the scan tool, read the active FCM DTC's.

Does the scan tool display this DTC as active?

Yes

Go To 7

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) .

7. (F1) FUSED IGNITION SWITCH OUTPUT WIRE SHORT TO GROUND

Go To 5

Yes

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