What does it mean?
On the seventh ignition control channel the module output rests at a defined voltage and drops only when a spark is commanded. P036B is stored when the module reads a voltage below its low threshold at a time when the line should be at rest, which is the signature of a short to ground or of a coil igniter input that has failed shorted. The module normally shuts the channel down to protect its output transistor, so the coil stops firing altogether. Because the harness branch to the rear coils runs close to heat shields and brackets, a grounded wire is a particularly common finding on this channel.
Symptoms
- Steady misfire on the cylinder served by this channel, with shaking at idle
- MIL on and flashing when the misfire is heavy
- Loss of power and jerking under acceleration
- Hard starting and an unstable idle speed
- Unburnt fuel smell from the exhaust
- Reduced power or limp mode on some vehicles
Likely causes
- Control wire grounded where the insulation has been worn through by a bracket or heat shield
- Internally shorted igniter in the seventh coil
- Water or oil in the coil connector bridging the control pin to ground
- Harness pinched under an engine cover or intake component after previous service work
- Insulation melted where the loom passes close to the exhaust manifold
- Module output driver shorted, confirmed only after the external circuit has been cleared
How to fix it
- Confirm the affected cylinder from the misfire counters and freeze frame data
- Unplug the coil and check whether the low voltage disappears at the module connector, which separates coil from harness
- Measure resistance from the control wire to ground with both ends disconnected
- Inspect the harness branch to the rear of the engine, giving special attention to heat shields, brackets and clips
- Check the coil connector and plug well for oil, water and corrosion
- Fit a known good coil temporarily to see whether the fault follows the part
- Repair the short with a soldered and insulated joint, clear the code and re-check the misfire counters under load