This tutorial will help you determine the cause of a misfire or 'no-spark, no-start' condition on your GM car, pickup, mini-van, van or SUV equipped with a 4.3L, or 5.0L, or 5.7L engine.

The tests are explained step by step to make the whole diagnosis and troubleshooting as painless as possible.

You can use the tests in this article to test and diagnose: A bad ignition control module (ICM), or ignition coil, or a bad distributor cap, or bad spark plug wires.

A full list of GM vehicles covered by these tests is at the bottom of the page (mobile device) or on the left column (laptop/PC).

The following tutorials will also help you:

En Español You can find this tutorial in Spanish here: Cómo Verificar El Sistema De Encendido (GM Vortec 4.3L, 5.0L, 5.7L) (at: autotecnico-online.com).

Symptoms Of A Bad ICM, Ignition Coil, Spark Plug Wires, Or Dist. Cap

If your GM car (or pickup, van or mini-van) suffers a misfire; the check engine light (CEL) will illuminate to let you know that YES, something is indeed wrong.

Here are a few other symptoms your vehicle may experience with a misfire condition:

  1. Diagnostic trouble codes (DTC) stored in the computer's (PCM) memory:
    • P0300, P0301, P0302, P0303, P0304, P0305, P0306, P0307, P0308.
  2. Misfire that does not light up the check engine light (CEL).
  3. No power.
  4. Idles rough.
  5. Bad gas mileage.
  6. Black smoke coming out of the tail pipe.
  7. Rotten egg smell coming out of the tail pipe.
  8. Smell of unburned gasoline coming out of the tail pipe.
  9. Won't pass the state emissions test.
  10. Cranks but doesn't start.

Basic GM Ignition System Theory

To successfully diagnose a misfire or no-start problem in your GM car (pickup, van, SUV, or minivan), it helps to understand how spark is generated and delivered to the engine cylinders.

In short, this is what happens when you turn the key and start the engine:

  1. The crankshaft position (CKP) sensor starts generating its signal and feeding it to the PCM (Powertrain Control Module = Fuel Injection Computer).
  2. The PCM uses this signal to know where each piston is in relation to its combustion cycle, and with this information the PCM knows when to start activating the ignition control module (ICM), activating the injectors, and a host of other things needed to get your vehicle started.
  3. After receiving the CKP signal, the PCM sends the ignition control module (ICM) a trigger signal that tells the ICM exactly when to fire the ignition coil. This trigger signal is known in GM service literature as the IC (Ignition Control) signal.
  4. The ignition control module will now begin to open and close the ignition coil's primary circuit and as you may already know, it's this opening and closing action that causes the ignition coil to spark. This opening and closing process is referred to in this article as a switching signal.
  5. The spark produced by the ignition coil is sent to the distributor cap via a high voltage wire and from there to each engine cylinder via a spark plug wire.

With the simple and easy tests presented in this testing article, you can find the exact cause of your vehicle's misfire or no-start problem (if it's ignition system related) while saving you time and money in the process.

Ignition System Diagnostic Manual Download

This tutorial contains a lot of information you need to diagnose and solve the ignition system problem that's causing your GM vehicle's no-start problem or misfire problem.

However, if you want access to a wiring diagram, ignition component pinouts and the entire testing procedure in one place, then take a look at the following:

Chevrolet/GMC C/K Series Full Size Pickups:

1996 Chrevrolet/GMC Full Size Pickups PDF
Engines: 4.3L, 5.0L, 5.7L, 7.4L
1996 Full Size Pickup
Ignition System No-Start Diagnostic Manual

$3.99 USD

 

All of the information you need to diagnose a misfire or a no-start problem (caused by the ignition coil, the ignition module, or the crankshaft position sensor).

Diagnostic manual comes with:

  • Wiring diagrams.
  • Component pin outs.
  • Connector pin outs.
  • Ignition system component part numbers.
  • Firing orders.
  • Complete step-by-step testing instructions.

The illustrations in the diagnostic manual are printer friendly! Applies to:

  • 1996 Chevrolet C1500, C2500, C3500 Pickup.
  • 1996 Chevrolet K1500, K2500, K3500 Pickup.
  • 1996 GMC C1500, C2500, C3500 Pickup.
  • 1996 GMC K1500, K2500, K3500 Pickup.
1997 Chrevrolet/GMC Full Size Pickups PDF
Engines: 4.3L, 5.0L, 5.7L, 7.4L
1997 Full Size Pickup
Ignition System No-Start Diagnostic Manual

$3.99 USD

 

All of the information you need to diagnose a misfire or a no-start problem (caused by the ignition coil, the ignition module, or the crankshaft position sensor).

Diagnostic manual comes with:

  • Wiring diagrams.
  • Component pin outs.
  • Connector pin outs.
  • Ignition system component part numbers.
  • Firing orders.
  • Complete step-by-step testing instructions.

The illustrations in the diagnostic manual are printer friendly! Applies to:

  • 1997 Chevrolet C1500, C2500, C3500 Pickup.
  • 1997 Chevrolet K1500, K2500, K3500 Pickup.
  • 1997 GMC C1500, C2500, C3500 Pickup.
  • 1997 GMC K1500, K2500, K3500 Pickup.
1998 Chrevrolet/GMC Full Size Pickups PDF
Engines: 4.3L, 5.0L, 5.7L, 7.4L
1998 Full Size Pickup
Ignition System No-Start Diagnostic Manual

$3.99 USD

 

All of the information you need to diagnose a misfire or a no-start problem (caused by the ignition coil, the ignition module, or the crankshaft position sensor).

Diagnostic manual comes with:

  • Wiring diagrams.
  • Component pin outs.
  • Connector pin outs.
  • Ignition system component part numbers.
  • Firing orders.
  • Complete step-by-step testing instructions.

The illustrations in the diagnostic manual are printer friendly! Applies to:

  • 1998 Chevrolet C1500, C2500, C3500 Pickup.
  • 1998 Chevrolet K1500, K2500, K3500 Pickup.
  • 1998 GMC C1500, C2500, C3500 Pickup.
  • 1998 GMC K1500, K2500, K3500 Pickup.
1999 Chrevrolet/GMC Full Size Pickups PDF
Engines: 4.3L, 5.0L, 5.7L, 7.4L
1999 Full Size Pickup
Ignition System No-Start Diagnostic Manual

$3.99 USD

 

All of the information you need to diagnose a misfire or a no-start problem (caused by the ignition coil, the ignition module, or the crankshaft position sensor).

Diagnostic manual comes with:

  • Wiring diagrams.
  • Component pin outs.
  • Connector pin outs.
  • Ignition system component part numbers.
  • Firing orders.
  • Complete step-by-step testing instructions.

The illustrations in the diagnostic manual are printer friendly! Applies to:

  • 1999 Chevrolet Silverado, C1500, C2500, C3500 Pickup.
  • 1999 Chevrolet K1500, K2500, K3500 Pickup.
  • 1999 GMC Sierra, C1500, C2500, C3500 Pickup.
  • 1999 GMC K1500, K2500, K3500 Pickup.
2000 Chrevrolet/GMC Full Size Pickups PDF
Engines: 4.3L, 5.7L, 7.4L
2000 Full Size Pickup
Ignition System No-Start Diagnostic Manual

$3.99 USD

 

All of the information you need to diagnose a misfire or a no-start problem (caused by the ignition coil, the ignition module, or the crankshaft position sensor).

Diagnostic manual comes with:

  • Wiring diagrams.
  • Component pin outs.
  • Connector pin outs.
  • Ignition system component part numbers.
  • Firing orders.
  • Complete step-by-step testing instructions.

The illustrations in the diagnostic manual are printer friendly! Applies to:

  • 2000 Chevrolet Silverado, C2500, C3500 Pickup.
  • 2000 Chevrolet K1500, K2500, K3500 Pickup.
  • 2000 GMC Sierra, C2500, C3500 Pickup.
  • 2000 GMC K1500, K2500, K3500 Pickup.

Chevrolet Express Van and GMC Savana Van:

1996-1999 Chrevrolet Express/GMC Savana PDF
Engines: 4.3L, 5.0L, 5.7L, 7.4L
1996-1999 Express/Savana
Ignition System No-Start Diagnostic Manual

$3.99 USD

 

All of the information you need to diagnose a misfire or a no-start problem (caused by the ignition coil, the ignition module, or the crankshaft position sensor).

Diagnostic manual comes with:

  • Wiring diagrams.
  • Component pin outs.
  • Connector pin outs.
  • Ignition system component part numbers.
  • Firing order.
  • Complete step-by-step testing instructions.

The illustrations in the diagnostic manual are printer friendly! Applies to:

  • 1996-1999 Chevrolet Express Van.
  • 1996-1999 GMC Savana Van.
2000 Chrevrolet Express/GMC Savana PDF
Engines: 4.3L, 5.0L, 5.7L, 7.4L
2000 Express/Savana
Ignition System No-Start Diagnostic Manual

$3.99 USD

 

All of the information you need to diagnose a misfire or a no-start problem (caused by the ignition coil, the ignition module, or the crankshaft position sensor).

Diagnostic manual comes with:

  • Wiring diagrams.
  • Component pin outs.
  • Connector pin outs.
  • Ignition system component part numbers.
  • Firing order.
  • Complete step-by-step testing instructions.

The illustrations in the diagnostic manual are printer friendly! Applies to:

  • 2000 Chevrolet Express Van.
  • 2000 GMC Savana Van.

Chevrolet Tahoe and GMC Yukon:

1996-2000 Chrevrolet Tahoe/GMC Yukon PDF
Engines: 5.7L
1996-2000 Tahoe/Yukon
Ignition System No-Start Diagnostic Manual

$3.99 USD

 

All of the information you need to diagnose a misfire or a no-start problem (caused by the ignition coil, the ignition module, or the crankshaft position sensor).

Diagnostic manual comes with:

  • Wiring diagram.
  • Component pin outs.
  • Connector pin outs.
  • Ignition system component part numbers.
  • Firing order.
  • Complete step-by-step testing instructions.

The illustrations in the diagnostic manual are printer friendly! Applies to:

  • 1996-2000 Chevrolet Tahoe (4x2 and 4x4).
  • 1996-2000 GMC Yukon (4x2 and 4x4).

Chevrolet and GMC Suburban:

1996-1999 Chrevrolet/GMC Suburban PDF
Engines: 5.7L, 7.4L
1996-1999 Suburban
Ignition System No-Start Diagnostic Manual

$3.99 USD

 

All of the information you need to diagnose a misfire or a no-start problem (caused by the ignition coil, the ignition module, or the crankshaft position sensor).

Diagnostic manual comes with:

  • Wiring diagram.
  • Component pin outs.
  • Connector pin outs.
  • Ignition system component part numbers.
  • Firing order.
  • Complete step-by-step testing instructions.

The illustrations in the diagnostic manual are printer friendly! Applies to:

  • 1996-1999 Chevrolet Suburban (4x2 and 4x4).
  • 1996-1999 GMC Suburban (4x2 and 4x4).
Chevrolet Vehicles:
  • Astro
    • 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005
  • Blazer
    • 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005
  • Blazer TrailBlazer
    • 1999, 2000, 2001
Chevrolet Vehicles:
  • C1500, C2500, C3500 Pick Up
    • 1996, 1997, 1998, 1999, 2000
  • Express Van 1500, 2500, 3500
    • 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007
  • G30 Van
    • 1996
  • K1500, K2500, K3500 Pick Up
    • 1996, 1997, 1998, 1999, 2000
Chevrolet Vehicles:
  • K1500, K2500 Suburban
    • 1996, 1997, 1998, 1999
  • P30 Van
    • 1996, 1997, 1998, 1999
  • S10 Blazer
    • 1994
  • S10 Pick Up
    • 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004
Chevrolet Vehicles:
  • Silverado 1500 Pick Up
    • 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2007
  • Tahoe
    • 1996, 1997, 1998, 1999, 2000
GMC Vehicles:
  • Sierra C1500, C2500, C3500
    • 1996, 1997, 1998, 1999, 2000
GMC Vehicles:
  • Suburban C1500, C2500
    • 1996, 1997, 1998, 1999
  • G3500 Van & Vandura
    • 1996
  • Jimmy & Envoy
    • 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005
  • K1500, K2500, K3500 Sierra
    • 1996, 1997, 1998, 1999, 2000
GMC Vehicles:
  • P3500 Van
    • 1996, 1997, 1998, 1999
  • S15 Jimmy
    • 1994
  • Safari
    • 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005
GMC Vehicles:
  • Savana Van 1500, 2500, 3500
    • 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007
  • Sonoma
    • 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004
GMC Vehicles:
  • Yukon
    • 1996, 1997, 1998, 1999, 2000, 2001, 2002
Isuzu Vehicles:
  • Hombre
    • 1997, 1998, 1999, 2000
Oldsmobile Vehicles:
  • Bravada
    • 1996, 1997, 1998, 1999, 2000, 2001
Cadillac Vehicles:
  • Escalade
    • 1999, 2000