B2185

B2185-IGNITION UNLOCK/RUN/START CONTROL CIRCUIT HIGH





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

Theory of Operation

The family of B2100 Diagnostic Trouble Codes (DTCs) typically describes ignition performance related faults. These are often caused by a contradiction of switch status information. For example, if an Electronic Control Unit (ECU) receives a bussed message indicating ignition switch position but the state of a hardwired ignition circuit indicates another switch position a B2100 series DTC would likely result.

These DTCs can be caused by a number of conditions including:

- loose connections
- missing or blown fuses
- faulty component
- vehicle no start or long crank time

Verify the proper operation of the starting system and verify that this DTC is active before proceeding with the diagnostic test.

- When Monitored:
With the ignition on.

- Set Condition:
The Front Control Module (FCM) will set this if the Left Trailer Tow Brake Lamp Relay Control circuit is shorted to ground for greater than 2seconds.





1. CHECK FOR ACTIVE DTC
1. Turn the ignition on.
2. With the scan tool, read the active DTCs.
3. Cycle the ignition switch from off to on, leaving the ignition on for a minimum of 30 seconds.
4. 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. (F1) FUSED IGNITION SWITCH OUTPUT (UNLOCK-RUN-START) CIRCUIT SHORT TO VOLTAGE




1. Turn the ignition off.
2. Disconnect the IPM C5 harness connector.
3. Disconnect the PCM C1 harness connector.
4. Turn the ignition on.
5. Measure the voltage of the (F1) Fused Ignition Switch Output (Unlock-Run-Start) circuit at the IPM C5 harness connector.

Is voltage present?

Yes

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

No

- Go To 3

3. POWERTRAIN CONTROL MODULE INTERNALLY SHORTED




1. Reconnect the Powertrain Control Module C1 harness connector.
2. Measure the voltage of the (F1) Fused Ignition Switch Output (Unlock-Run-Start) circuit at the IPM C5 harness connector.

Is voltage present?

Yes

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

No

- Go To 4

4. CHECK FCM AND IPM FOR A SHORT TO VOLTAGE
1. Disconnect the Front Control Module from the IPM.
2. Measure the voltage at the male terminal of the IPM C5 connector.

Is voltage present?

Yes

- Replace the IPM.
- Perform the BODY VERIFICATION TEST. Body Verification Test

No

- Replace the FCM.
- Perform the BODY VERIFICATION TEST. Body Verification Test