What does it mean?
Ignition G is the seventh ignition control channel, which means the engine has at least seven separate coil outputs, typically a V8 or a larger unit. Coils in these positions often sit at the back of the engine where access is poor and heat soak is high, and the harness branch that reaches them is the longest in the ignition loom. P036A is stored when the module commands the G channel and finds no electrical load on it at all: no current can flow, which is the definition of an open circuit. The coil never fires, so the cylinder it serves contributes nothing to the engine's output and the misfire monitor records it as well.
Symptoms
- One dead cylinder with a steady misfire and strong vibration at idle
- MIL on and flashing under load
- Marked loss of power, especially when the engine is pulling hard
- Hard starting and extended cranking
- Fuel smell from the exhaust and rising catalytic converter temperature
- Cylinder specific misfire codes stored alongside
Likely causes
- Broken control wire in the long harness branch that feeds the seventh coil
- Connector not fully latched, or a terminal pushed out after work at the rear of the engine
- Open igniter input inside the coil
- Corroded terminals from water running down the rear of the cylinder head or oil in the plug well
- Harness chafed against a bracket, heat shield or bulkhead
- Missing coil supply or ground, so the input stage cannot present a load
- Module ignition driver failure, considered only after the harness is proven good
How to fix it
- Use the misfire counters to establish which cylinder the G channel drives
- Inspect the connector latch, terminal seating and the harness branch that runs to the rear coils, since these are the most exposed
- Test continuity from the module pin to the coil pin while flexing the harness to expose an intermittent break
- Confirm battery voltage on the coil supply pin and a clean ground connection
- Check with an oscilloscope whether a trigger pulse actually leaves the module on this channel during cranking
- Move the coil to another cylinder position and see whether the fault follows the component
- Repair the open wiring or renew the coil, clear the code and verify the misfire counters stay clear under load