However, it's not the only possibility. Many other components can cause similar symptoms, including:
* Crankshaft Position Sensor (CKP): This sensor tells the computer the engine's rotational speed and position. A faulty CKP will prevent the engine from starting.
* Cam Position Sensor (CMP): Similar to the CKP, but for the camshaft. A bad CMP will also disrupt ignition timing and prevent starting.
* Ignition Coil(s): Worn or failing coils can produce weak or inconsistent spark.
* Battery/Charging System: A weak battery or alternator can prevent enough power from reaching the ignition system.
* Fuel Delivery System: Issues with the fuel pump, fuel filter, injectors, or pressure regulator can also prevent starting.
* Temperature Sensor: An inaccurate temperature sensor can cause the computer to adjust the fuel/air mixture incorrectly, leading to hard starting, especially when cold.
Troubleshooting Steps:
Before replacing the ICM, it's best to perform some diagnostics to narrow down the possibilities:
1. Check the battery and charging system: Make sure the battery is properly charged and the alternator is functioning correctly. A simple voltage test is all you need for this.
2. Inspect the ignition coil(s): Look for any visible damage, cracks, or corrosion.
3. Check for spark: With a spark tester, check if the spark plugs are receiving a strong, consistent spark. If not, the problem lies somewhere in the ignition system (ICM, coil, wires).
4. Have the codes read: Use an OBD-II scanner to read any diagnostic trouble codes (DTCs) stored by the engine control module (ECM). These codes can pinpoint the likely culprit.
5. Check fuel pressure: If you suspect a fuel problem, measure the fuel pressure at the fuel rail.
Replacing the ICM:
While replacing the ICM is relatively straightforward, it requires some mechanical aptitude. You'll need to access it (usually near the distributor) and disconnect the electrical connectors carefully. Always consult a repair manual specific to your 1998 Suburban for detailed instructions and safety precautions.
In short, the ICM *could* be the problem, but a proper diagnosis is crucial to avoid unnecessary parts replacements. Start with the simpler checks (battery, etc.) and proceed to more involved diagnostics. If you're not comfortable with automotive repair, take it to a qualified mechanic for diagnosis and repair.
