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Home / DTC / P0579 — Cruise Control Multi-Function Input A Circuit Range/Performance

P0579 — Cruise Control Multi-Function Input A Circuit Range/Performance

Detailed page for trouble code P0579.

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22,491specific
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Code

P0579

Generic P — Powertrain

Cruise Control Multi-Function Input A Circuit Range/Performance

Brand: Generic
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Open or shorted wiring between the multi-function switch (steering wheel/cruise switch) and the PCM
  • Corroded, loose, or damaged connector or terminal at the switch or PCM
  • Faulty multi-function/cruise control switch or steering wheel control module
  • Poor or missing ground or reference voltage to the switch circuit
  • Intermittent harness damage (pinch, chafing) or water intrusion causing changing voltage readings
  • Faulty PCM/input circuit (less common)

Symptoms

  • Malfunction Indicator Lamp (MIL) may be illuminated
  • Cruise control unavailable or will not engage
  • Cruise may disengage unexpectedly or behave erratically
  • Cruise control switches on steering wheel not responding or intermittent operation
  • No driveability issues apart from cruise control (typically)

What to check

  • Retrieve and record freeze-frame data and pending/history for P0579 with a scan tool
  • Monitor live data for the cruise multi-function input while operating the switch(s) and observing changes
  • Visually inspect connectors and wiring at the multi-function switch, steering column, and PCM for damage, corrosion, or loose pins
  • Backprobe the switch connector and measure voltage/ground reference with a DVOM or lab scope while operating the switch
  • Perform a wiggle test on the wiring harness and connector while monitoring the input signal for intermittent changes
  • Check ground and reference supply voltages to the switch circuit at key points (switch connector and PCM)

Signal parameters

  • Expected signal: discrete switch-type signal or 0–5 V logic-level range depending on vehicle design
  • Stable, repeatable voltage transitions when pressing/releasing cruise switches (no rapid fluctuation or drifting)
  • No high-resistance or open-circuit readings in continuity tests between switch and PCM

Diagnostic algorithm

  1. Connect an OBD-II scan tool; read and record P0579 and any related codes and freeze-frame data
  2. Monitor live data for the multi-function input A while operating the cruise/steering switches; note voltage or state changes and any intermittent behavior
  3. Visually inspect switch, steering column harness, and PCM connector for damage, corrosion, pin push-out, or water intrusion
  4. Backprobe the switch connector with a DVOM or scope. Verify proper reference voltage, ground, and that the signal changes cleanly when switches are operated
  5. If signal is intermittent or absent, perform continuity checks between the switch pins and the PCM input pin; repair any open or high-resistance circuits
  6. If a short to voltage or ground is suspected, isolate and repair wiring short (disconnect connectors, measure at each segment)
  7. If wiring and connectors check good, bench-test or replace the multi-function/cruise switch assembly and retest
  8. If problem remains after replacing switch and repairing wiring, consider PCM input circuit diagnosis or replacement by qualified technician
  9. Clear codes and perform a road test to verify repair and confirm P0579 does not return

Likely causes

  • Damaged connector or terminal at the cruise switch
  • Open/short in the harness between the switch and PCM (common when steering column moved)
  • Failed multi-function/cruise switch assembly

Fault status

⚠️ Status
Cruise Control Multi-Function Input A Circuit Range/Performance — input signal out of expected range or unstable. Cruise control may be disabled and a fault logged.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-2.5 hours

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Code

P0579

GWM P — Powertrain

- Cruise control system malfunction

Brand: GWM
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Open or shorted wiring between the multi-function switch (steering wheel/cruise switch) and the PCM
  • Corroded, loose, or damaged connector or terminal at the switch or PCM
  • Faulty multi-function/cruise control switch or steering wheel control module
  • Poor or missing ground or reference voltage to the switch circuit
  • Intermittent harness damage (pinch, chafing) or water intrusion causing changing voltage readings
  • Faulty PCM/input circuit (less common)

Symptoms

  • Malfunction Indicator Lamp (MIL) may be illuminated
  • Cruise control unavailable or will not engage
  • Cruise may disengage unexpectedly or behave erratically
  • Cruise control switches on steering wheel not responding or intermittent operation
  • No driveability issues apart from cruise control (typically)

What to check

  • Retrieve and record freeze-frame data and pending/history for P0579 with a scan tool
  • Monitor live data for the cruise multi-function input while operating the switch(s) and observing changes
  • Visually inspect connectors and wiring at the multi-function switch, steering column, and PCM for damage, corrosion, or loose pins
  • Backprobe the switch connector and measure voltage/ground reference with a DVOM or lab scope while operating the switch
  • Perform a wiggle test on the wiring harness and connector while monitoring the input signal for intermittent changes
  • Check ground and reference supply voltages to the switch circuit at key points (switch connector and PCM)

Signal parameters

  • Expected signal: discrete switch-type signal or 0–5 V logic-level range depending on vehicle design
  • Stable, repeatable voltage transitions when pressing/releasing cruise switches (no rapid fluctuation or drifting)
  • No high-resistance or open-circuit readings in continuity tests between switch and PCM

Diagnostic algorithm

  1. Connect an OBD-II scan tool; read and record P0579 and any related codes and freeze-frame data
  2. Monitor live data for the multi-function input A while operating the cruise/steering switches; note voltage or state changes and any intermittent behavior
  3. Visually inspect switch, steering column harness, and PCM connector for damage, corrosion, pin push-out, or water intrusion
  4. Backprobe the switch connector with a DVOM or scope. Verify proper reference voltage, ground, and that the signal changes cleanly when switches are operated
  5. If signal is intermittent or absent, perform continuity checks between the switch pins and the PCM input pin; repair any open or high-resistance circuits
  6. If a short to voltage or ground is suspected, isolate and repair wiring short (disconnect connectors, measure at each segment)
  7. If wiring and connectors check good, bench-test or replace the multi-function/cruise switch assembly and retest
  8. If problem remains after replacing switch and repairing wiring, consider PCM input circuit diagnosis or replacement by qualified technician
  9. Clear codes and perform a road test to verify repair and confirm P0579 does not return

Likely causes

  • Damaged connector or terminal at the cruise switch
  • Open/short in the harness between the switch and PCM (common when steering column moved)
  • Failed multi-function/cruise switch assembly

Fault status

⚠️ Status
Cruise Control Multi-Function Input A Circuit Range/Performance — input signal out of expected range or unstable. Cruise control may be disabled and a fault logged.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-2.5 hours

Similar codes

P0578 P0562 P0563
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Code

P0579

HUMMER P — Powertrain

Cruise Control Related Malfunction

Brand: HUMMER
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Open or shorted wiring between the multi-function switch (steering wheel/cruise switch) and the PCM
  • Corroded, loose, or damaged connector or terminal at the switch or PCM
  • Faulty multi-function/cruise control switch or steering wheel control module
  • Poor or missing ground or reference voltage to the switch circuit
  • Intermittent harness damage (pinch, chafing) or water intrusion causing changing voltage readings
  • Faulty PCM/input circuit (less common)

Symptoms

  • Malfunction Indicator Lamp (MIL) may be illuminated
  • Cruise control unavailable or will not engage
  • Cruise may disengage unexpectedly or behave erratically
  • Cruise control switches on steering wheel not responding or intermittent operation
  • No driveability issues apart from cruise control (typically)

What to check

  • Retrieve and record freeze-frame data and pending/history for P0579 with a scan tool
  • Monitor live data for the cruise multi-function input while operating the switch(s) and observing changes
  • Visually inspect connectors and wiring at the multi-function switch, steering column, and PCM for damage, corrosion, or loose pins
  • Backprobe the switch connector and measure voltage/ground reference with a DVOM or lab scope while operating the switch
  • Perform a wiggle test on the wiring harness and connector while monitoring the input signal for intermittent changes
  • Check ground and reference supply voltages to the switch circuit at key points (switch connector and PCM)

Signal parameters

  • Expected signal: discrete switch-type signal or 0–5 V logic-level range depending on vehicle design
  • Stable, repeatable voltage transitions when pressing/releasing cruise switches (no rapid fluctuation or drifting)
  • No high-resistance or open-circuit readings in continuity tests between switch and PCM

Diagnostic algorithm

  1. Connect an OBD-II scan tool; read and record P0579 and any related codes and freeze-frame data
  2. Monitor live data for the multi-function input A while operating the cruise/steering switches; note voltage or state changes and any intermittent behavior
  3. Visually inspect switch, steering column harness, and PCM connector for damage, corrosion, pin push-out, or water intrusion
  4. Backprobe the switch connector with a DVOM or scope. Verify proper reference voltage, ground, and that the signal changes cleanly when switches are operated
  5. If signal is intermittent or absent, perform continuity checks between the switch pins and the PCM input pin; repair any open or high-resistance circuits
  6. If a short to voltage or ground is suspected, isolate and repair wiring short (disconnect connectors, measure at each segment)
  7. If wiring and connectors check good, bench-test or replace the multi-function/cruise switch assembly and retest
  8. If problem remains after replacing switch and repairing wiring, consider PCM input circuit diagnosis or replacement by qualified technician
  9. Clear codes and perform a road test to verify repair and confirm P0579 does not return

Likely causes

  • Damaged connector or terminal at the cruise switch
  • Open/short in the harness between the switch and PCM (common when steering column moved)
  • Failed multi-function/cruise switch assembly

Fault status

⚠️ Status
Cruise Control Multi-Function Input A Circuit Range/Performance — input signal out of expected range or unstable. Cruise control may be disabled and a fault logged.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-2.5 hours

Similar codes

P0578 P0562 P0563
Repair manuals

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Code

P0579

LAND ROVER P — Powertrain

Multifunction Speed Control Input A - Circuit Range / performance

Brand: LAND ROVER
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Open or shorted wiring between the multi-function switch (steering wheel/cruise switch) and the PCM
  • Corroded, loose, or damaged connector or terminal at the switch or PCM
  • Faulty multi-function/cruise control switch or steering wheel control module
  • Poor or missing ground or reference voltage to the switch circuit
  • Intermittent harness damage (pinch, chafing) or water intrusion causing changing voltage readings
  • Faulty PCM/input circuit (less common)

Symptoms

  • Malfunction Indicator Lamp (MIL) may be illuminated
  • Cruise control unavailable or will not engage
  • Cruise may disengage unexpectedly or behave erratically
  • Cruise control switches on steering wheel not responding or intermittent operation
  • No driveability issues apart from cruise control (typically)

What to check

  • Retrieve and record freeze-frame data and pending/history for P0579 with a scan tool
  • Monitor live data for the cruise multi-function input while operating the switch(s) and observing changes
  • Visually inspect connectors and wiring at the multi-function switch, steering column, and PCM for damage, corrosion, or loose pins
  • Backprobe the switch connector and measure voltage/ground reference with a DVOM or lab scope while operating the switch
  • Perform a wiggle test on the wiring harness and connector while monitoring the input signal for intermittent changes
  • Check ground and reference supply voltages to the switch circuit at key points (switch connector and PCM)

Signal parameters

  • Expected signal: discrete switch-type signal or 0–5 V logic-level range depending on vehicle design
  • Stable, repeatable voltage transitions when pressing/releasing cruise switches (no rapid fluctuation or drifting)
  • No high-resistance or open-circuit readings in continuity tests between switch and PCM

Diagnostic algorithm

  1. Connect an OBD-II scan tool; read and record P0579 and any related codes and freeze-frame data
  2. Monitor live data for the multi-function input A while operating the cruise/steering switches; note voltage or state changes and any intermittent behavior
  3. Visually inspect switch, steering column harness, and PCM connector for damage, corrosion, pin push-out, or water intrusion
  4. Backprobe the switch connector with a DVOM or scope. Verify proper reference voltage, ground, and that the signal changes cleanly when switches are operated
  5. If signal is intermittent or absent, perform continuity checks between the switch pins and the PCM input pin; repair any open or high-resistance circuits
  6. If a short to voltage or ground is suspected, isolate and repair wiring short (disconnect connectors, measure at each segment)
  7. If wiring and connectors check good, bench-test or replace the multi-function/cruise switch assembly and retest
  8. If problem remains after replacing switch and repairing wiring, consider PCM input circuit diagnosis or replacement by qualified technician
  9. Clear codes and perform a road test to verify repair and confirm P0579 does not return

Likely causes

  • Damaged connector or terminal at the cruise switch
  • Open/short in the harness between the switch and PCM (common when steering column moved)
  • Failed multi-function/cruise switch assembly

Fault status

⚠️ Status
Cruise Control Multi-Function Input A Circuit Range/Performance — input signal out of expected range or unstable. Cruise control may be disabled and a fault logged.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-2.5 hours

Similar codes

P0578 P0562 P0563
325

Browse 325 LAND ROVER manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

LAND ROVER

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+100 karma for a short comment :)
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Code

P0579

MERCEDES-BENZ P — Powertrain

Cruise Control Related Malfunction

Brand: MERCEDES-BENZ
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Open or shorted wiring between the multi-function switch (steering wheel/cruise switch) and the PCM
  • Corroded, loose, or damaged connector or terminal at the switch or PCM
  • Faulty multi-function/cruise control switch or steering wheel control module
  • Poor or missing ground or reference voltage to the switch circuit
  • Intermittent harness damage (pinch, chafing) or water intrusion causing changing voltage readings
  • Faulty PCM/input circuit (less common)

Symptoms

  • Malfunction Indicator Lamp (MIL) may be illuminated
  • Cruise control unavailable or will not engage
  • Cruise may disengage unexpectedly or behave erratically
  • Cruise control switches on steering wheel not responding or intermittent operation
  • No driveability issues apart from cruise control (typically)

What to check

  • Retrieve and record freeze-frame data and pending/history for P0579 with a scan tool
  • Monitor live data for the cruise multi-function input while operating the switch(s) and observing changes
  • Visually inspect connectors and wiring at the multi-function switch, steering column, and PCM for damage, corrosion, or loose pins
  • Backprobe the switch connector and measure voltage/ground reference with a DVOM or lab scope while operating the switch
  • Perform a wiggle test on the wiring harness and connector while monitoring the input signal for intermittent changes
  • Check ground and reference supply voltages to the switch circuit at key points (switch connector and PCM)

Signal parameters

  • Expected signal: discrete switch-type signal or 0–5 V logic-level range depending on vehicle design
  • Stable, repeatable voltage transitions when pressing/releasing cruise switches (no rapid fluctuation or drifting)
  • No high-resistance or open-circuit readings in continuity tests between switch and PCM

Diagnostic algorithm

  1. Connect an OBD-II scan tool; read and record P0579 and any related codes and freeze-frame data
  2. Monitor live data for the multi-function input A while operating the cruise/steering switches; note voltage or state changes and any intermittent behavior
  3. Visually inspect switch, steering column harness, and PCM connector for damage, corrosion, pin push-out, or water intrusion
  4. Backprobe the switch connector with a DVOM or scope. Verify proper reference voltage, ground, and that the signal changes cleanly when switches are operated
  5. If signal is intermittent or absent, perform continuity checks between the switch pins and the PCM input pin; repair any open or high-resistance circuits
  6. If a short to voltage or ground is suspected, isolate and repair wiring short (disconnect connectors, measure at each segment)
  7. If wiring and connectors check good, bench-test or replace the multi-function/cruise switch assembly and retest
  8. If problem remains after replacing switch and repairing wiring, consider PCM input circuit diagnosis or replacement by qualified technician
  9. Clear codes and perform a road test to verify repair and confirm P0579 does not return

Likely causes

  • Damaged connector or terminal at the cruise switch
  • Open/short in the harness between the switch and PCM (common when steering column moved)
  • Failed multi-function/cruise switch assembly

Fault status

⚠️ Status
Cruise Control Multi-Function Input A Circuit Range/Performance — input signal out of expected range or unstable. Cruise control may be disabled and a fault logged.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-2.5 hours

Similar codes

P0578 P0562 P0563
856

Browse 856 MERCEDES-BENZ manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

MERCEDES-BENZ

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+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
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