🚨 Diagnostic Profile
Vehicle Make: Buick
Technical Description: IC Output High/Pulse Detected When Grounded – Cylinder 8
This code indicates that the Powertrain Control Module (PCM) has detected an unexpected high-voltage signal or erratic pulse on the Ignition Control (IC) circuit for cylinder 8 while the circuit was commanded to ground. This typically points to a fault within the ignition coil driver circuit, a shorted or damaged coil, or a wiring issue between the PCM and the ignition coil for cylinder 8. The IC circuit is responsible for triggering coil dwell and spark timing, so any irregularity can cause misfires, rough idle, or a no-start condition on the affected cylinder.
🚨 Repair Difficulty Tier
Difficulty Rating: Intermediate
This repair requires the use of a diagnostic scan tool capable of reading live ignition control data and a digital multimeter (DMM) or oscilloscope to verify waveform integrity on the IC circuit. While the repair does not involve airbags or safety restraint systems, it does require moderate electrical diagnostic knowledge, including the ability to test coil-on-plug (COP) ignition systems and interpret PCM driver circuit behavior. A basic home mechanic may struggle without proper electrical testing equipment, but an experienced DIYer or intermediate-level technician can complete this job with the right tools.
🛠️ Resolution Steps
Step 1: Preliminary Inspection
Begin by visually inspecting the ignition coil assembly for cylinder 8, checking for cracked housings, carbon tracking, or signs of arcing. Inspect the wiring harness and connector pins leading to the coil for corrosion, bent pins, or chafed insulation. Confirm that the coil is properly seated and that the connector locks securely. Check for any aftermarket modifications or recent repairs near the ignition harness that could have introduced a pinched or shorted wire.
Step 2: Diagnostic Verification
Connect a scan tool and monitor live data for the IC circuit on cylinder 8, paying attention to dwell time, misfire counters, and voltage feedback patterns. Using a digital multimeter, verify the ignition coil’s primary and secondary resistance values against OEM specifications. If available, use an oscilloscope to capture the IC signal waveform while cranking or running the engine — look for voltage spikes or irregular pulse patterns that exceed normal control signal thresholds. Swap the suspected coil with a known-good coil from another cylinder to see if the fault follows the component.
Step 3: Resolution & Reset Process
If the ignition coil tests out of specification or visually shows damage, replace it with an OEM or OEM-equivalent coil. Repair or replace any damaged wiring or connector terminals identified during inspection. After the repair, clear the diagnostic trouble codes (DTCs) using the scan tool and perform a PCM reset or ignition cycle to confirm the fault does not return. Conduct a test drive under varying load conditions to ensure stable ignition performance and confirm no new misfire or IC-related codes are triggered.
📦 Parts, Labor, and Budget Estimates
Required Components/Software: Ignition coil (cylinder 8), OEM wiring harness connector/pigtail (if damaged), diagnostic scan tool with live data capability, digital multimeter or oscilloscope.
Average Component Price: $35 – $120 for a replacement OEM or OEM-equivalent ignition coil; $20 – $60 for wiring harness repair components if needed.
Estimated Labor Hours: 0.5 – 1.5 hours for diagnostic testing and coil replacement; additional 0.5 – 1.0 hour if wiring harness repair is required.