Code
P1640
SATURN
P — Powertrain
Driver 1 Input High Voltage
AI status
Completed
Completed
100%
Causes
- Short to battery/constant 12V on the Driver 1 input circuit
- Wiring insulation damage or pin short between circuits
- Corroded, bent or pushed‑out connector pins
- Faulty sensor, switch or component tied to Driver 1 input
- Faulty body/engine control module (incorrect internal reference or driver)
- Aftermarket equipment or incorrect replacement parts causing voltage feed
Symptoms
- Associated circuit/component not working or behaving intermittently
- Related dash warning light(s) or stored additional DTCs
- Poor module/vehicle functions tied to the Driver 1 circuit
- Possible battery drain or blown fuses in severe short cases
What to check
- Read and record all stored DTCs and freeze frame data with a scan tool
- Verify battery voltage and charging system health (measure with engine on/off)
- Visually inspect wiring harnesses, connectors and ground points for damage or corrosion around Driver 1 circuit
- Check fuses and relays related to the affected circuit
- Backprobe the input pin at the module and at the component with key on to measure voltage
- Wiggle test wiring while monitoring voltage for intermittent opens/shorts
Signal parameters
- Expected: low (near 0 V) when inactive for many sensor/switch inputs, or switched 12 V when designed as a switched input — consult factory manual for exact expected behavior
- Fault condition: input voltage above the module’s allowed threshold (manufacturer-specific). Often reported when voltage is higher than expected logic/sensor range (e.g., above sensor supply/reference or above ~5 V on low‑voltage sensor circuits)
- Check for voltage spikes or rise to battery voltage (~12–14 V) when fault is present
Diagnostic algorithm
- Retrieve freeze frame and related DTCs. Note when the fault occurred and any patterns.
- Verify battery and charging voltage (12.4–12.9 V key off; ~13.5–14.5 V charging). Correct battery/charging faults first.
- Identify the exact circuit/component that is “Driver 1” using the factory wiring diagram/service manual.
- Visually inspect the harness, connector and pins for that circuit at the component and module; repair any damage.
- With ignition on (engine off), backprobe the Driver 1 input at the component and at the module. Measure voltage and compare to expected values from the manual.
- If voltage is high at the module end with the component disconnected, suspect a short to battery or damaged harness between module and power source. Isolate by testing sections of the harness for continuity to battery using the connector separation method.
- If voltage is only high at the component end, test/replace the component (sensor/switch) or repair connector. Verify resistance values per service data.
- Use an oscilloscope if intermittent or transient spikes are suspected to capture voltage behavior during operation.
- Repair or replace wiring, connector, component or module as indicated by test results. After repair, clear codes and perform a test drive/repeat checks to confirm the fault does not return.
Likely causes
- Short to battery on the input wire (most common)
- Corroded/loose connector at the module or component
- Failed external component feeding the input
Fault status
Status
On-board control module detected an over-voltage condition on the Driver 1 input circuit (P1640) and stored the code. Further diagnostics required to locate source of high voltage.
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
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