Ignition module failure
Ignition module failure is a common ignition-related problem on the Pontiac Fiero, especially on V6 cars with distributor ignition.
A failing ignition module can cause a no-start condition, stalling, misfiring, intermittent shutdown, or a hot engine that will not restart until it cools down.
Overview
The ignition module is part of the ignition system and works with the distributor pickup coil, ignition coil, ECM, wiring, and related connectors.
Ignition module problems can be difficult to diagnose because failures may be intermittent. A module may work when cold but fail when hot, or it may fail suddenly without warning.
Symptoms
Common symptoms include:
- Engine cranks but does not start
- Engine starts cold but stalls when hot
- Engine shuts off suddenly while driving
- Engine restarts after cooling down
- No spark
- Intermittent spark
- Misfire
- Tachometer does not move while cranking
- Stored Code 42 in some cases
Related components
Ignition module diagnosis should also include nearby and related parts:
- Ignition coil
- Distributor
- Pickup coil
- Spark plugs
- Spark plug wires
- Ignition timing
- ECM
- Ground problems
- Wiring harness
Heat-related failure
Ignition modules can fail from heat, age, poor electrical connections, poor heat transfer, or low-quality replacement parts.
When replacing an ignition module, proper heat-sink compound should be used between the module and the distributor mounting surface. Ordinary dielectric grease is not the same as thermal compound and should not be used as a substitute for heat transfer.
Diagnosis
A practical diagnostic order is:
- Determine whether the engine has spark.
- Watch the tachometer while cranking.
- Inspect ignition module connectors.
- Inspect the distributor pickup coil and wiring.
- Test or substitute the ignition module if appropriate.
- Check the ignition coil.
- Check ignition power and ground.
- Read Diagnostic trouble codes.
- Inspect related wiring and ECM connections.
No-start diagnosis
Ignition module failure is one possible cause of a crank/no-start condition.
Related topics:
Replacement
When replacing the ignition module:
- Disconnect the battery if appropriate.
- Remove the distributor cap as needed.
- Disconnect the module connectors carefully.
- Remove the old module.
- Clean the mounting surface.
- Apply proper heat-sink compound.
- Install the replacement module.
- Reconnect wiring.
- Verify spark and engine operation.
Notes
Ignition module failure should not be diagnosed by symptoms alone. Pickup coil failure, ignition coil failure, bad connectors, poor grounds, wiring faults, ECM issues, and fuel problems can produce similar symptoms.
Many Fiero owners keep a spare ignition module and the tools needed to replace it because sudden ignition module failure can leave the car stranded.