What does it mean?
Ignition H is the eighth ignition control channel, so this code belongs to engines with at least eight coil outputs. The eighth coil is often the one furthest from the control module and the hardest to reach, which means its connector spends its life exposed to heat and vibration. P036D is stored when the module commands the H channel and finds no electrical load on it: the trigger is sent but no current can flow, which is an open circuit. The affected coil never fires, so its cylinder is dead and the misfire monitor normally logs it at the same time.
Symptoms
- Dead cylinder with a steady misfire and heavy vibration at idle
- MIL on and flashing when the engine is loaded
- Clear loss of power and poor acceleration
- Hard starting and long cranking
- Fuel smell from the exhaust and a risk of catalytic converter damage
- Cylinder specific misfire codes stored with this entry
Likely causes
- Broken control wire between the module and the eighth coil
- Connector unlatched, cracked or with a terminal backed out after previous work
- Open igniter input inside the coil
- Corroded terminals caused by moisture and long-term heat cycling at this position
- Harness chafed against a heat shield, bracket or engine cover
- Coil supply or ground missing, so the input stage cannot load the line
- Module ignition driver failure, treated as the last possibility
How to fix it
- Identify which cylinder the H channel drives from the misfire counters before removing anything
- Inspect the connector for latch damage, terminal seating and corrosion, since this position suffers most from heat and vibration
- Test continuity from the module pin to the coil pin, flexing the harness during the measurement
- Confirm supply voltage and a clean ground at the coil connector
- Look for a trigger pulse on this channel with an oscilloscope while cranking
- Move the coil to another position to see whether the fault follows the part
- Repair the open circuit or renew the coil, then clear the code and verify under load