Ignition Control
B2104-IGNITION UNLOCK RUN/START CONTROL CIRCUIT LOWB2104 - Ignition Unlock RUN/start Control Circuit Low:
WHEN MONITORED
With the ignition on.
SET CONDITION
The Front Control Module will set this DTC within 500 ms 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
- 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 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.
Q: 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.
2. 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.
Q: Does the scan tool display this DTC as active?
YES: Go To 3
NO: Replace the Powertrain Control Module. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test
3. (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.
Q: Is the resistance below 1000.0 ohms?
NO: Go To 4
YES: Repair the (F1) Fused Ignition Switch Output circuit for a short to ground. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test
4. 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.
Q: Is the resistance below 1000.0 ohms?
YES: Replace the Integrated Power Module. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test
NO: Replace and program the Front Control Module. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test