Code
P1645
DAEWOO
P — Powertrain
Injector driving voltage flt
Views:
UK: 4
EN: 7
RU: 4
AI status
Completed
Completed
100%
Causes
- Damaged or corroded injector connector or wiring harness
- Open circuit or short to battery/ground in injector feed or return circuit
- Faulty fuel injector (shorted or open coil)
- Blown fuse or failed fuel/injector relay (power supply issue)
- Poor ground connection at engine/ECM
- Faulty ECU/PCM driver transistor
Symptoms
- Check Engine Light with code P1645
- Rough idle or engine misfire
- Hard starting or no start
- Reduced engine power or limp performance
- Increased fuel consumption and poor drivability
- Intermittent faults that may clear or return
What to check
- Read and record freeze frame/live data with a scan tool; note related codes
- Visually inspect injector connectors and wiring for damage, corrosion, or oil/water contamination
- Check injector fuse(s) and relevant relay(s); verify battery voltage at relay and injectors
- Backprobe injector connector while cranking to verify driver pulse and voltage
- Measure injector coil resistance with an ohmmeter and compare to specification
- Perform wiggle test on harness while monitoring scanner for changes
Signal parameters
- Supply voltage to injector when open: approx. battery voltage (~11–14.5 V)
- Driver output when energized: switched to ground (voltage near 0 V at injector pin while commanded)
- Pulse width: typically 1–10 ms (varies with engine speed/load)
- Injector coil resistance (typical multi-point): ~10–16 Ω; some injectors may be lower (1–5 Ω) or higher—consult vehicle spec
- No injector pulse or constant high/low voltage at driver pin indicates open/short/driver fault
Diagnostic algorithm
- Retrieve all stored codes and freeze-frame data; note any multiple injector or misfire codes.
- Visually inspect the wiring harness, connectors, and injector boots for damage, corrosion, or contamination.
- Verify battery voltage and check the fuse(s) and relay that supply injector power; replace if faulty.
- With ignition on (engine off), backprobe the injector power terminal to confirm constant battery voltage is present.
- Crank engine and backprobe injector driver terminal; confirm proper pulsed switching to ground using a DVOM or, preferably, an oscilloscope.
- Measure injector coil resistance at the connector (pin to pin) and compare to spec; if out of range, bench-test or replace injector.
- If one cylinder is affected, swap suspect injector with a known-good cylinder and check if the fault/code follows the injector.
- If wiring shows intermittent open/short, repair harness or connector (repair, solder, heat-shrink, replace connector as needed).
- If wiring and injector are good but driver output is abnormal (constant high, no switching, or short to battery), suspect ECU driver failure—confirm with scope and consult service manual before replacing ECU.
- Clear codes and retest. If fault reoccurs, continue deeper diagnostics or replace failed component as confirmed.
Likely causes
- Wiring/connector damage (broken wire, chafe, corrosion)
- Poor power supply or ground to injector circuit (fuse/relay/ground)
- Faulty injector coil (internal short or open)
- ECU driver failure (less common but possible)
Fault status
Status
Injector driving voltage fault detected by PCM: abnormal voltage or signal on injector driver circuit indicating possible open, short, poor connection, faulty injector, or ECU driver problem.
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
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