Table 1: | Correct Ignition Switch Inputs |
Table 2: | Incorrect Ignition Switch Inputs |
The body control module (BCM) is the power mode master responsible for sending ignition switch position information on the class 2 serial data link. The BCM monitors 3 discrete wires from the ignition switch contacts and the engine run flag (ERF) in order to determine the present power mode. The BCM communicates this power mode information to all class 2 modules on the class 2 serial data link. The following table represents correct BCM power mode data:
Ignition Switch Position | BCM input and Scan Tool Display | ||
---|---|---|---|
Ignition Accessory | Ignition 1 | Ignition 0 | |
OFF | Inactive | Off | Off |
ACC | Active | Off | Off |
ON | Active | On | On |
START | Inactive | On | On |
The only requirements are voltage and ground.
One of the 3 monitored ignition switch circuits has malfunctioned. The DTC will set, if one of the following situations is present:
BCM Input and Scan Tool Display | Engine Running | ||
---|---|---|---|
Ignition Accessory | Ignition 1 | Ignition 0 | |
Inactive | On | Off | No |
Active | Off | Off | No |
Active | On | Off | No |
Inactive | On | Off | Yes |
Inactive¹ | On | On | Yes |
Active | Off | Off | Yes |
Active | Off | On | Yes |
Active | On | Off | Yes |
¹ The module sets the DTC 1 minute after it detects the condition. |
The BCM implements default actions for each ignition switch position when faults are detected.
• | A current DTC clears when the malfunction is no longer present. |
• | A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction. |
Step | Action | Yes | No | ||||||
---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Body Control System Schematics Connector End View Reference: Body Control System Connector End Views | |||||||||
1 | Perform the Diagnostic System Check for the system exhibiting the symptom. Refer to Control Module References . Did you perform the Diagnostic System Check? | Go to Step 2 | |||||||
2 |
Does the scan tool indicate that all inputs are inactive/Off? | Go to Step 3 | Go to Step 6 | ||||||
3 |
Does the scan tool indicate that the Ignition 0 and Ignition Accessory inputs are active/On? | Go to Step 4 | Go to Step 8 | ||||||
4 |
Does the scan tool indicate that the all inputs are active/On? | Go to Step 5 | Go to Step 8 | ||||||
5 |
Important: The engine may start in this step. Turn the engine OFF immediately after reviewing the input data.
Does the scan tool indicate that the Ignition 0 and Ignition 1 inputs are On and the Ignition Accessory input is inactive? | Go to Step 11 | Go to Step 8 | ||||||
6 |
Does the scan tool indicate that any of the Ignition 0, Ignition 1 or Ignition Accessory inputs is active/On? | Go to Step 7 | Go to Step 9 | ||||||
7 |
Did you find and correct the condition? | Go to Step 14 | Go to Step 11 | ||||||
8 |
Does the scan tool indicate that the suspect circuits are now active/On? | Go to Step 9 | Go to Step 10 | ||||||
9 | Inspect for poor connections at the ignition switch harness connectors. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 14 | Go to Step 12 | ||||||
10 |
Did you find and correct the condition? | Go to Step 14 | Go to Step 11 | ||||||
11 | Inspect for poor connections at the BCM harness connectors. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 14 | Go to Step 13 | ||||||
12 | Replace the ignition switch. Refer to Ignition and Start Switch Replacement in Steering Wheel and Column. Did you complete the replacement? | Go to Step 14 | -- | ||||||
13 |
Important: Perform the programming or setup procedure for the module if required. Replace the BCM. Refer to Body Control Module Replacement . Did you complete the replacement? | Go to Step 14 | -- | ||||||
14 |
Does the DTC reset? | Go to Step 2 | System OK |