P1640

Code

BUICK P — Powertrain

Driver 1 Input High Voltage

Brand: BUICK

Type: P — Powertrain

Views: UK: 34 EN: 41 RU: 52

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Page language: EN

Malfunction or loss of function of the component driven by Driver 1
Related warning lamp or message illuminated (check engine or module-specific lamp)
Stored DTC P1640 and possible related stored/active codes
Intermittent operation or no operation of the associated circuit

Retrieve DTC(s) and freeze frame data with a scan tool; note conditions when the code set
Visual inspection of wiring, connectors, and harnesses for damage, corrosion, or water intrusion
Backprobe and measure voltage at the Driver 1 input pin with key ON and engine OFF and with the component commanded on and off
Check for continuity to battery and to ground; check for unintended continuity between Driver 1 and constant 12V
Disconnect the driven device and see if the code clears or voltage returns to expected level
Check related fuses, relays and power distribution for proper operation

Expected idle/input low: approximately 0–1 V (when circuit should be low)
Expected active or battery-fed level: approximately battery voltage (~12–14 V) only when legitimately driven
Fault threshold: input reads higher than expected when it should be low (commonly >5 V or near battery voltage when circuit should be low)
Reference: no more than a few tenths of a volt at an input that should be low; persistent battery-level voltage indicates a fault

Confirm the code with a scan tool and record freeze frame and any related codes.
Identify the exact circuit referred to as Driver 1 from vehicle wiring diagrams and module pinouts.
Perform visual inspection of connectors and wiring for damage, corrosion, or signs of heat/wear.
With key ON (engine OFF), backprobe the Driver 1 input pin and measure voltage. Note voltage with the circuit commanded off and commanded on (if safe).
If voltage is high when circuit should be low, disconnect the external device/connector. If voltage drops to expected level, suspect the external device or its wiring (inspect device and harness).
If voltage remains high with device disconnected, check for pin-to-battery short in harness (inspect splices, run-to-ground test, isolate sections of the harness).
Check grounds and battery feeds for proper connections and continuity.
Repair any wiring or connector faults found, then clear codes and retest under the same conditions that originally set the code.
If wiring and external device check good and the fault persists, suspect internal module driver/input failure — verify with module bench tests or consult manufacturer service info for module replacement/reprogramming steps.
After repair or replacement, erase codes and perform a road or functional test to confirm the issue is resolved.

Pin-to-battery short at connector or harness splice
Damaged insulation allowing contact with constant 12V feed
Corrosion or bent pin causing unintended contact
Failed external device connected to Driver 1 (e.g., actuator, injector, solenoid) internally shorted to battery
Control module driver transistor or input comparator failure

⚠️ Status

Driver 1 input voltage above allowable range — possible short to battery or circuit/component fault.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0 - 2.5 hours

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P1640 — Driver 1 Input High Voltage