Circuit Description
When the key is turned to the crank position, power is supplied to the starter relay terminal 85. After receiving the proper theft deterrent signal from the body control module (BCM), the powertrain interface module (PIM), will supply a ground signal to the starter relay, terminal 86. This will energize the starter relay and allow the starter motor to operate. If there is a problem with the starter relay coil (shorted internally) or the starter relay control circuit (shorted to voltage) that is allowing 12 volts on the starter relay control circuit, this will cause excessive current flow through the PIM causing DTC B3027 to set.
Conditions for Running the DTC
| • | The ignition switch is in the crank position. |
| • | The ignition voltage is between 5-17 volts. |
Conditions for Setting the DTC
The PIM detects excessive current through the starter relay control circuit.
Action Taken When the DTC Sets
| • | The PIM will shut down the starter relay control circuit. |
| • | The powertrain control module (PCM) will not illuminate the malfunction indicator lamp (MIL). |
Conditions for Clearing the DTC
| • | A Last Test Failed (current DTC) clears, after the ignition has been cycled and the PIM no longer detects excessive current flow through the starter relay circuit. |
| • | The DTC can be cleared by using the scan tool Clear DTC Information function. |
Diagnostic Aids
The following may cause an intermittent condition:
| • | Incorrectly routed harness |
| • | Rubbed through wire insulation |
| • | Broken wire inside the insulation |
Refer to: Testing for Intermittent Conditions and Poor Connections in Body and Accessories-Wiring Systems.
Test Description
The number below refers to the step number on the diagnostic table.
-
This test checks to see if the relay is causing the high voltage problem.
-
This test checks to see if the PIM is causing the problem.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Starting and Charging Schematics Connector End View Reference: Engine Electrical Connector End Views | |||
1 | Did you perform the Engine Electrical Diagnostic System Check? | Go to Step 2 | |
Does the test lamp illuminate? | Go to Step 3 | Go to Step 4 | |
3 | While the test light is still connected to PIM harness connector, disconnect the starter relay. Does the test lamp remain illuminated? | Go to Step 5 | Go to Step 6 |
4 |
Does PIM DTC B3027 reset? | Go to Step 7 | Go to Step 10 |
Repair short to voltage in the starter relay control circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 10 | -- | |
6 | Inspect for poor connections at the starter relay. 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 10 | Go to Step 8 |
7 | Inspect for poor connections at the PIM. 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 10 | Go to Step 9 |
8 | Replace the starter relay. Refer to Electrical Center Identification Views in Body and Accessories-Wiring Systems. Did you complete the replacement? | Go to Step 10 | -- |
9 | Replace the PIM. Refer to Powertrain Interface Module Replacement in Body Control System. Did you complete the replacement? | Go to Step 10 | -- |
10 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 2 |
