P0602 - Control Module Programming Error
System
Powertrain (Engine & Gearbox)
Technical Description
The control module has detected a fault in the Control Module Programming Error (P0602). The module sees no circuit at all — broken wire, backed-out pin, or a failed sensor.
Multimeter Test Points & Nominal Values
| Test Point / Component | Measurement | Nominal Target Range | Test Condition |
|---|---|---|---|
| Control Module Programming Error – Permanent B+ Supply | Voltage (V) | 12.4 - 12.7 V (ignition OFF) / 13.5 - 14.7 V (engine running) | At module supply pins |
| Control Module Programming Error – Ignition-Switched Supply | Voltage (V) | 11.8 - 14.4 V | Ignition ON |
| Control Module Programming Error – Ground Connections Voltage Drop | Voltage (V) | < 0.1 V per ground point | Under load to battery negative |
| Control Module Programming Error – 5 V Reference Outputs | Voltage (V) | 4.95 - 5.05 V per circuit | Ignition ON, sensors unplugged one at a time |
At module supply pins
Ignition ON
Under load to battery negative
Ignition ON, sensors unplugged one at a time
Oscilloscope Waveform Analysis
500 ms/div, 5 V/divPossible Causes
Open circuit, damaged wiring harness, or disconnected plug at Control Module Programming Error
Chafed or pinched wiring harness along the signal path to Control Module Programming Error
Poor ground connection or excessive voltage drop (> 0.1 V) at the ground point for Control Module Programming Error
Defective internal output driver or reference circuit in the control module for Control Module Programming Error
Symptoms
4
Recommended Solution
Verify continuity (< 0.5 Ω) on the signal wire between the component plug and the ECM header connector.
Verify loaded supply voltage and harness terminal pins at Control Module Programming Error.
Check circuit continuity and ground-side voltage drop (< 0.05 V) for Control Module Programming Error.
Inspect module enclosure and connector headers for water ingress, fretting corrosion, or PCB thermal damage.
Mechanic's Tip
When facing a 5V reference supply DTC, never replace the module first. A shorted external sensor (such as A/C pressure or EGR position) drags down the shared 5V internal rail. Unplug sensors one by one until 5V recovers.