Question about GMC Cars & Trucks

2 Answers

I've replaced everything to do with ignition spark on ky 1998 gmc pickup it has a 350 vortech engine why am I jot getting spark at the spark plugs ?

Posted by steve harwell on


2 Answers

Jeff Armer

  • Level 3:

    An expert who has achieved level 3 by getting 1000 points


    An expert that got 20 achievements.


    An expert that got 10 achievements.


    An expert that got 5 achievements.

  • GMC Master
  • 15,575 Answers

There is a lot involved in this ignition system ,maybe you should take it to a ASE certified repair facility !
The ignition system initiates combustion by providing a spark to ignite the compressed air and fuel mixture at the correct time. In order to provide an improved engine performance, fuel economy, and control of exhaust emissions, the control module controls the distributor spark advance, or timing, with the ignition control (IC) system.
The ignition system uses a primary and secondary sub system in order to accomplish the timed spark distribution. The primary system consists of a low voltage trigger device which determines the base timing. This signal is modified by the ignition control driver (ICD) module. The signal travels to either or both the engine and transmission processor, or control module, for base timing reference. Another signal is sent back to the ignition control driver (ICD) module, which has been adjusted by the control module, advanced or retarded, in order to trigger the coil, according to the requirements of the engine.
The secondary system consists of the ignition coil which has primary (low voltage) windings and secondary (high voltage) windings. The secondary side of the ignition coil generates a high voltage which high tension spark plug wires deliver to the spark plugs.
The control module controller now controls the ignition control (IC) and bypass functions.
In order to properly control the ignition or combustion timing, the control module needs to know the following things:
The crankshaft position

The engine speed (RPM)

The engine load -- Manifold pressure or vacuum

The atmospheric or barometric pressure

The engine coolant temperature

The camshaft position (CMP) sensor

System Operation
The enhanced ignition system used on all OBD II engines somewhat resembles the current distributor ignition (DI) system described in the Ignition Systems. However, the system has been greatly enhanced in order to make it compatible with the new OBD II regulations. The enhanced ignition system provides a spark at precisely the correct time in order to ignite the air and fuel mixture for optimum performance and fuel economy. The system consists of the following components:
Vehicle control module (VCM)


Ignition coil driver module

Ignition coil

Crankshaft position (CKP) sensor

This system does not use the ignition module used on the DI systems in the past. The VCM controller now controls the ignition control (IC) and bypass functions.
The crankshaft sensor, located in the front engine cover, is perpendicular to a target wheel attached to the crankshaft. The target wheel is equipped with slots situated 60 degrees apart. As the crankshaft rotates, the target wheel rotates past the crankshaft position sensor. The rising and falling edges created by the slots cause a signal to be sent back to the VCM. This signal occurs three times per crankshaft revolution and is referred to as the 3x signal for V6 applications. The signal occurs four times per crankshaft revolution and is referred to as the 4x signal for V8 applications.
The VCM then utilizes this 3x (V6) or 4x (V8) signal in order to provide the correct spark to the engine by way of the single coil driver module. The single coil driver module is basically an electronic switch that when commanded by the VCM, causes the primary coil voltage to breakdown, energizing the secondary coil and providing a spark via the coil wire to the distributor cap. The distributor consists of the following components:
Cap and rotor

Camshaft position sensor

Gear drive and shaft

The camshaft drives the distributor shaft which rotates providing a spark to the correct cylinder by way of the cap and rotor. The camshaft position (CMP) sensor functions much like the crankshaft sensor previously described but provides only a 1x signal to the VCM. That is, for every 2 rotations of the crankshaft, there is 1 rotation of the camshaft. Note that the camshaft position sensor will not affect driveability. The sole purpose of the camshaft position sensor is to provide the VCM with the necessary information for the misfire diagnostic trouble codes (DTCs).
Ignition Coil Driver Module and Ignition Coil The ignition coil driver module is mounted on a bracket next to the coil. The VCM signals the ICD to turn ON primary current to the ignition coil by pulling the IC line high (4 volts). The ICD turns the primary current ON and OFF by applying and removing the ground to the primary winding at the appropriate time. This module is of minimum function. The module does not contain backup calibrations that allows the engine to continue to run if the IC signal is lost.
Did you check for battery voltage at the coil on the pink wire an on ignition control module pink wire an at the crankshaft position sensor pink wire ?

Posted on Apr 19, 2015

  • 2 more comments 
  • Jeff Armer Apr 19, 2015

    I forgot does the dist. turn , these are known problems .Diagnostic Aids

  • Jeff Armer Apr 19, 2015

    The IC control circuit for an intermittent short to ground.

  • Jeff Armer Apr 19, 2015

    Check the following when the distributor rotor does not rotate, while engine is cranking:

  • Jeff Armer Apr 19, 2015

    • A broken distributor drive shaft , A worn distributor drive gear or camshaft timing chain and gears




  • Level 1:

    An expert who has achieved level 1.

    New Friend:

    An expert that has 1 follower.

  • Contributor
  • 1 Answer

There is a spark control modal in the distributor most books do not tell you about it . if you have replaced everything else try that

Posted on Apr 19, 2015


5 Related Answers


  • 8 Answers

SOURCE: diagram for replacing an ignition switch for 1998 gmc pickup

>>>>FIRST disable the air bag system
You'll need to remove the upper and lower steering column covers.
Also all the trim under the drivers side, kneee bolster, etc...
The ignition switch has 2 screws holding it on.
Remove those screws and all related wiring harness.
Then the switch.
Here is the procedure from GM......

Place the multifunction lever in the center or the OFF position.
Caution: Unless directed otherwise, the ignition and start switch must be in the OFF or LOCK position, and all electrical loads must be OFF before servicing any electrical component. Disconnect the negative battery cable to prevent an electrical spark should a tool or equipment come in contact with an exposed electrical terminal. Failure to follow these precautions may result in personal injury and/or damage to the vehicle or its components.

Disconnect the battery negative cable.
Disable the SIR system.
Remove the steering wheel inflator module.
Remove the horn plunger contact.
Remove the steering wheel.
Remove the tilt wheel lever.
Remove the ignition lock cylinder. Remove the upper steering column trim cover.
Couldnt find a diagram. Hope this helps.

Posted on Jan 02, 2009

Richard Delahant

  • 1201 Answers

SOURCE: 1992 dodge 318 engine turns over, but no start. No

Some dodges have an oblong shaped white ceramic block, either mounted on the firewall or on inner fender well, with wire connections, one on each end, if there is one, replace it.

Posted on Mar 16, 2009


  • 38 Answers

SOURCE: GMC 2500 P/U 350 Vortec.. Installed rebuilt

Have you checked to see if your distributor is aligned properly? I just had to change out a distributor on a 1997 GMC 3/4 ton that has the V8 Vortec in it as well and you need to pay attention to the (2) numbers around the mating surface / rim of the distributor. You should see a number 8 and a number 6. You need to find TDC on your number 1 cyl. You can either slowly crank the motor over or turn the motor over with a ratchet and socket on the bolt securing the main pully to the crank while another person places their finger over the spark plug hole and when it just starts to Stop pushing air out past your finger then stop. Is the rotor aligned with the number what ever size engine you have in your truck (i.e. 6 or 8)? If not then your timing is off. You will need to remove the distributor and rotor, then install your rotor (before re-installing the distributor) and align the rotor pointer with either the number 8 or 6 stamped on the lip of the distributor where the cap sits down and creates the seal. I have found that they run both numbers on the distributor because they use the same distributor in both the V6 and V8 Vortec motors or a least the plastic base of the distributor. There will be (2) numbers here and sometimes hard to see. Align the pointer with what size engine you have and lower the distributor down into the hole. If the end of the shaft starts to turn the rotor as it aligns with the oil pump causing the pointer to no longer be pointed at the number that indicates which engine this is being installed in then you need to remove the distributor and look down into the hole where the distributor goes in and you'll see the end of the oil pump shaft with a slot (perfect for a big flat head screwdriver) staring back up at you. You'll need to insert a long shanked large flat head screwdriver down into the hole and turn the slotted oil pump shaft until you can successfully lower the distrubutor into place and not lose your mark. I also found that you'll need to have to pointer of the rotor a bit retarted from where it is suppose to be. This is because the distributor shaft gear is swirled and will cause the rotor to turn as it finds its mark, aligns and lowers down into a seated position. When it is seated and the rotor has stopped turning it should be pointing at the indicated cylinder Stamp in the lip that is your size motor (V6 or V8). Now it should be on time. The computer will take care of advancing and retarding.

If not the timing, then I would also consider that you may have a bad crank shaft sensor. These are merley suggestions because there is no more to go on than what you've submitted.

Posted on Mar 29, 2009


  • 34 Answers

SOURCE: 1997 chevy silverado 1500 350 vortech, new fule pump not working

before you drop tank again, check fuses & relay.then disconnect fuel line @ filter turn key to on position should hear fuel pump run and get gas stream out of line. if no flow from line new pump faulty be sure & remove negative battery cable first good luck.

Posted on Jun 20, 2009


Greg Bernett

  • 2989 Answers

SOURCE: need fireing order for 1998 gmc 2500 pickup, 454 engine

Here ya go:


Posted on Apr 18, 2010

Add Your Answer

Uploading: 0%


Complete. Click "Add" to insert your video. Add



Related Questions:

1 Answer

1996 gmc pickup, getting spark, & fuel to the rail, injectors not fuel comeing from injectors. Could it be the ignition module ?

Backprobe with a t pin or straight pin the connectors on the injectors and spin the engine over to see if they are being pulsed. One terminal should pulse and the other will not. Is it 350 or 454 ?

Jul 05, 2015 | GMC Cars & Trucks

1 Answer

Chevy c1500 no spark

I agree, the ECM

Jan 08, 2014 | Cars & Trucks

1 Answer

I have a 98 350 vortec engine rebuilt it will not start I get a couple pops I replaced the ignition control module Auto Zone said the coil was good. I crank the engine still won't start so I take 2 plugs...

Do you have spark at the plug end of the plug wires?Have you double checked the firing order is correct? If you are sure it is correct 1,8,4,3,6,5,7,2 ,then you will need to check the ignition timing,if that seems good then you may have to get into it a little and check the cam /valve timing..Hope this helps !

Jan 28, 2011 | 1998 GMC Sierra

1 Answer

I have a 1997 gmc 4x4 1/2 ton with a 5.7 vortech no spark

Have you checked the fuses? I think there are 2 ECM fuses if either one blows there will be no spark.

Dec 08, 2009 | 1997 Chevrolet K1500

2 Answers

1998 gmc jimmy

If your engine is a Vortech, most likely you have an intake leak going on. This is very common with the 5.7L Vortech and the 4.3L Vortech. A leaking intake will causing one side of the engine to lean and the other side will be normal.

Oct 24, 2008 | 2000 GMC Jimmy

Not finding what you are looking for?
Cars & Trucks Logo

Related Topics:

170 people viewed this question

Ask a Question

Usually answered in minutes!

Top GMC Experts


Level 3 Expert

85239 Answers

Colin Stickland
Colin Stickland

Level 3 Expert

22485 Answers

Jeffrey Turcotte
Jeffrey Turcotte

Level 3 Expert

8984 Answers

Are you a GMC Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides