Introduction:
The diagnostic trouble code (DTC) B1357 indicates a "Ignition Run Circuit Short To Battery" condition. This means the vehicle's computer has detected an unwanted electrical connection between the ignition run circuit and the battery voltage. This can cause various electrical malfunctions, prevent the engine from starting, or keep it running even after the key is removed. Understanding the causes, symptoms, and diagnostic procedures for this code is crucial for efficient troubleshooting and repair.
Table: B1357 Ignition Run Circuit Short To Battery
| Category | Description | Possible Causes |
|---|---|---|
| Definition | Ignition Run Circuit Short To Battery: The vehicle's computer (PCM/BCM) detects excessive voltage on the ignition run circuit. | Short circuit in the wiring harness, faulty ignition switch, malfunctioning relay, damaged PCM/BCM, aftermarket accessories improperly installed. |
| Symptoms | Engine won't start, engine continues to run after key is removed, battery drain, blown fuses, erratic electrical behavior, warning lights illuminated. | Dead battery, starter motor not engaging, lights staying on, instrument cluster malfunctions, other DTCs present related to electrical circuits. |
| Possible Causes (Detailed) | Damaged or frayed wiring insulation, wiring harness rubbing against metal parts, water intrusion, corrosion, loose connections, internal failure of components. | |
| Affected Components | Ignition switch, PCM (Powertrain Control Module), BCM (Body Control Module), Ignition relay, Wiring harness, Fuses, Battery. | Starter solenoid, fuel pump, injectors, sensors, other electrical components powered by the ignition run circuit. |
| Diagnostic Tools | Multimeter, scan tool, wiring diagrams, circuit tester, visual inspection tools. | OBD II scanner, digital volt-ohm meter (DVOM), test light, wire strippers, crimpers, soldering iron. |
| Diagnostic Steps | Verify DTC, inspect wiring, test ignition switch, check relays, isolate short, repair wiring, replace faulty components. | Visual inspection, continuity test, voltage test, resistance test, wiggle test, component activation. |
| Common Fixes | Repairing damaged wiring, replacing faulty ignition switch, replacing faulty relay, replacing damaged PCM/BCM. | Insulating exposed wires, cleaning corroded connections, properly installing aftermarket accessories, replacing blown fuses. |
| Severity | High: Can lead to vehicle malfunction, electrical fire, or safety hazards. | Immediate attention required to prevent further damage or potential dangers. |
| Related DTCs | B1352, B1359, B1360, other codes related to ignition or electrical circuits. | Codes indicating voltage or current issues in other circuits, codes related to specific components powered by the ignition run circuit. |
| Circuit Function | The ignition run circuit provides power to various vehicle systems when the ignition switch is in the "Run" or "Start" position. | Powers the fuel pump, injectors, ignition coil, sensors, and other critical components necessary for engine operation. |
| Voltage Range (Normal) | Typically battery voltage (12-14 volts) when the ignition is in the "Run" or "Start" position. | Voltage should drop to near zero when the ignition is in the "Off" position. |
| Common Locations for Shorts | Wiring harness near the steering column, engine compartment, or under the dashboard. | Areas where wiring is exposed to heat, moisture, or friction. |
| Aftermarket Accessory Impact | Improperly installed or faulty aftermarket accessories can cause shorts in the ignition run circuit. | Alarm systems, remote starters, audio systems, lighting upgrades. |
| Testing the Ignition Switch | Using a multimeter to check for continuity and voltage at the appropriate terminals in each switch position. | Verify that the switch provides power to the correct circuits in the "Run" and "Start" positions and that it cuts power when in the "Off" position. |
| Relay Testing | Using a multimeter to check for continuity and voltage at the relay terminals. Testing the relay coil to ensure it activates when voltage is applied. | Verify that the relay switches the ignition run circuit on and off as commanded by the PCM/BCM. |
Detailed Explanations:
Definition: The B1357 DTC signals that the vehicle's computer has detected higher-than-expected voltage on the ignition run circuit. This circuit is designed to supply power to essential engine and vehicle components when the ignition switch is in the "Run" or "Start" positions. A short to battery means the circuit is inadvertently receiving power directly from the battery, even when it shouldn't.
Symptoms: Several symptoms can indicate a B1357 code. These include the engine failing to start, the engine continuing to run even after the key is removed, unexplained battery drain, blown fuses, and erratic behavior in other electrical systems. Illuminated warning lights on the dashboard are also common.
Possible Causes (Detailed): The most common cause is damaged or frayed wiring insulation, which allows the wire to contact a grounded metal surface or another wire carrying battery voltage. Wiring harnesses rubbing against metal parts, water intrusion leading to corrosion, and loose electrical connections can also create short circuits. Internal failures within the ignition switch, relays, or even the PCM/BCM can also trigger the code.
Affected Components: The ignition switch is directly involved, as it controls the flow of power to the ignition run circuit. The PCM/BCM monitors the voltage on this circuit and sets the code if it detects an anomaly. The ignition relay acts as a switch, controlled by the PCM/BCM, to supply power to the circuit. The wiring harness provides the electrical pathways, and fuses are designed to protect the circuit from overcurrent. Finally, the battery is the source of power for the circuit.
Diagnostic Tools: A multimeter is essential for measuring voltage, resistance, and continuity. A scan tool is used to read the DTCs stored in the PCM/BCM. Wiring diagrams are crucial for understanding the circuit layout and identifying test points. A circuit tester or test light can be used to quickly check for power and ground. Visual inspection tools, such as a flashlight and inspection mirror, are helpful for examining wiring harnesses and components for damage.
Diagnostic Steps: The first step is to verify the DTC using a scan tool. Then, perform a thorough visual inspection of the wiring harness, paying close attention to areas where the harness may be rubbing against metal or exposed to heat or moisture. Test the ignition switch to ensure it is functioning correctly. Check the ignition relay for proper operation. If a short is suspected, use a multimeter to isolate the location of the short circuit. Repair the damaged wiring or replace the faulty components as needed.
Common Fixes: The most common fix is repairing damaged wiring by splicing in new sections of wire and properly insulating the connections. Replacing a faulty ignition switch or relay is also a frequent solution. In rare cases, the PCM/BCM may be damaged and require replacement. Ensuring proper installation of aftermarket accessories is crucial to prevent future problems. Replacing blown fuses is a temporary fix, but the underlying cause of the short circuit must be addressed.
Severity: A B1357 code is considered a high-severity issue because it can lead to vehicle malfunction, electrical fire, or safety hazards. The short circuit can cause excessive current draw, which can overheat wires and potentially ignite flammable materials. Immediate attention is required to prevent further damage or potential dangers.
Related DTCs: B1352 (Ignition Accessory Circuit Short To Battery), B1359 (Ignition Start Circuit Open), and B1360 (Ignition Run/Start Circuit Open) are related codes that indicate issues with other ignition circuits. Other codes related to voltage or current issues in other circuits powered by the ignition run circuit may also be present.
Circuit Function: The ignition run circuit's primary function is to provide power to various vehicle systems when the ignition switch is in the "Run" or "Start" position. This includes the fuel pump, injectors, ignition coil, sensors, and other critical components necessary for engine operation. Without this circuit, the engine will not run.
Voltage Range (Normal): Typically, the voltage on the ignition run circuit should be approximately battery voltage (12-14 volts) when the ignition is in the "Run" or "Start" position. The voltage should drop to near zero when the ignition is in the "Off" position. A higher voltage when the circuit is supposed to be off indicates a short to battery.
Common Locations for Shorts: Common locations for shorts include the wiring harness near the steering column, engine compartment, and under the dashboard. These areas are prone to movement, vibration, and exposure to environmental factors that can damage wiring. Areas where wiring is exposed to heat, moisture, or friction are particularly susceptible.
Aftermarket Accessory Impact: Improperly installed or faulty aftermarket accessories can often cause shorts in the ignition run circuit. Alarm systems, remote starters, audio systems, and lighting upgrades are common culprits. These accessories may tap into the ignition run circuit for power, and if the wiring is not properly insulated or the accessory is faulty, it can create a short.
Testing the Ignition Switch: Use a multimeter to check for continuity and voltage at the appropriate terminals in each switch position. Refer to a wiring diagram for the specific terminals to test. Verify that the switch provides power to the correct circuits in the "Run" and "Start" positions and that it cuts power when in the "Off" position. A faulty switch can cause intermittent or constant voltage on the ignition run circuit.
Relay Testing: Use a multimeter to check for continuity and voltage at the relay terminals. Test the relay coil to ensure it activates when voltage is applied. Verify that the relay switches the ignition run circuit on and off as commanded by the PCM/BCM. A malfunctioning relay can either fail to provide power to the circuit or, in the case of a shorted relay, provide constant power.
Frequently Asked Questions:
What does the B1357 code mean? It indicates a short to battery in the ignition run circuit, meaning the circuit is receiving power when it shouldn't.
What are the symptoms of a B1357 code? Common symptoms include the engine not starting, running after the key is removed, battery drain, and blown fuses.
Can a faulty ignition switch cause a B1357 code? Yes, a faulty ignition switch can cause a short to battery in the ignition run circuit.
How do I find a short in the wiring harness? Use a multimeter to perform continuity tests and isolate the section of the harness where the short is located.
Can aftermarket accessories cause this code? Yes, improperly installed or faulty aftermarket accessories can create shorts in the ignition run circuit.
Conclusion:
The B1357 Ignition Run Circuit Short To Battery code signifies a potentially serious electrical problem. Thorough diagnosis, using appropriate tools and techniques, is crucial to identify and repair the root cause of the short circuit. Addressing this issue promptly will prevent further damage and ensure the safe and reliable operation of your vehicle.