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My 1992 GMC S15 Sonoma 4.3 liter V6 has no spark.

yeloodmt yeloodmt
New User | Posts: 4 | Joined: 01/09
Posted: 01/10/09
07:55 PM

My truck just stop running while stopped at a light.  Turns over, fuel OK, but no spark to the distributor.  I have juice to the EMC, but not sure how to test for where the problem is.  Seems like it must be from the ECM to the ignition module, or the the ignition module, but not sure what wires to check from the ECM.  Also not sure if I am on the right track.
Any helpful ideas or solutions out there?  

waynep712 waynep712
Enthusiast | Posts: 651 | Joined: 10/08
Posted: 01/10/09
11:29 PM

i take it that you have a test light or some kind..  test both sides of every fuse under the left side of the dash board.. with the key on... there are probable 2 or 3 fuses under there.. ecm 1 and ecm 2   maybe more... check both sides of every fuse.. with the key on.. if you get power only on one side of any fuse.. that fuse is blown...    if you don't get any power on either side.. it is probably a fuse for something else...

check the pink wire on the coil with the test light..  it should have power with the key on...

there is more info here...

is it possible that the ignition rotor has burned through??    it has happened a bunch on various cars...  change it...   you will find spark from the coil and no spark at the plug wires when the rotor is perforated by the high voltage currents..

have you verified that the fuel pump works... ????  can you hear it for 2 seconds when someone turns on the key... ???

if not.. pound on the bottom of the gas tank with something.. a rubber hammer.. your fist..   but while someone is cranking the engine...  the pump is only powered when the key is turned on for 2 seconds.. then while the engine is being cranked... fuel pumps are brush type... the brushes wear...  pounding on the bottom of the gas tank while somebody is cranking the engine...  will 80 percent of the time get it to run ...   many times long enough to make it home..

there are so many things that could be wrong..

if you decide to pull the module.. examine the pick up coil connector for green colored grease.. it's not supposed to be green..   green is corrosion.. and may have eaten the copper wiring to the pick up coil...

do you have a digital volt meter...   if so...  can you clip it to the pick up coil wiring...    set it to 2 volt or 20 volt ac...   make sure the wires are not tangled in anything.. have someone crank the motor..    you should see over 1 volt AC on the pick up coil wiring ...  

with the module off...  you can get it tested at most chain parts store.. have them do it at least 6 times in a row..    be sure to use the dielectric tune up grease under the module.. it transfers the heat out of the module and to the housing .. or it will overheat and die...  usually in 30 to 45 minutes...

be sure to examine the ignition coil... they sometimes fail...   look on the outside of the round part of the coil.. close to the metal frame..  for circular power patterns..  if so... it might have an external high voltage leak.. so all the high voltage is going to the ground instead of through the wires , cap and plugs,,,  

yeloodmt yeloodmt
New User | Posts: 4 | Joined: 01/09
Posted: 01/11/09
02:44 PM

I have power to the new coil I replaced. I do not get a spark from the coil when cranking.  I have tested the red wires on the 2 plugs going into the coil and there is power in both.
Any ideas what the white wires do on these plugs and why I am not getting a spark from the coil?

Is there something I am missing?  Seems like power to the coil should result in a spark or power to the tip of the coil that the plug wires connect to the distributor.

I am stumped...........


waynep712 waynep712
Enthusiast | Posts: 651 | Joined: 10/08
Posted: 01/11/09
03:45 PM

time to pull the cap... and the module...     have it tested...   it still could be the pick up coil... about 70 percent of the time it is the module...

turning on the key sends power to the coil and module...   the module takes the signals from the pick up coil to decide when to make and break the ground to the coil.....     it the module is bad.. sometimes you will find that the coil will spark as you turn off the key...

the pick up coil generates ac voltage signals as the reluctor rotates inside the pickup coil...   it has to generate about 1 volt ac in order to cause the power transistor in the module to pull the coil wire to ground...    this completes the circuit through the primary side of the coil building a magnetic field...   when the pick up coil A C voltage drops to 0 and starts to go negative the power transistor is opened... the opening of the power transistor causes the magnetic field in the primary side of the coil to collapse through the secondary windings..   this generates the high voltage that comes out the coil high tension tower...  

yeloodmt yeloodmt
New User | Posts: 4 | Joined: 01/09
Posted: 01/11/09
05:30 PM

I replaced the module and all is good.

I really appreciate your thoughtful and concise information.  I love this forum and those that take the time to help with their knowledge.

Thanks again.


Matt-AZ Matt-AZ
New User | Posts: 2 | Joined: 01/09
Posted: 01/11/09
09:28 PM

May be a faulty ICM (ignition control module) I had one go bad that would intermittently act up, most often no spark/no start.  

mwatson1647 mwatson1647
New User | Posts: 9 | Joined: 12/11
Posted: 12/08/11
12:12 PM

Hello, I also have a 92 Sonoma that has a problem simular to what you explained.  It's a 2.5L 4cyl and has no spark.  I can't get any voltage at the coil when the ignition is on, and can't tell where the voltage is being lost between the ignition switch and the coil/distributor.  Were you able to determine if this could be caused by a defective ECM, or would it more likely be a shorted wire, burned fuse (all look OK in the fuse box under the dash), or a blown fusible link (if there is one between the ignition switch and the ECM)?  When I short the ALDL block to get the ECM in diagnotics mode, it seems to work because it gets code 12 (basically saying I'm here) and shows no stored trouble codes, but don't know if that means it's OK or not.  Any help would be appreciated. Thanks  

waynep7122 waynep7122
Addict | Posts: 4545 | Joined: 08/09
Posted: 12/08/11
12:39 PM

power from the ignition switch to the coil positive is direct....  what i do is probe the red wire to the coil with a test light while working the ignition switch slowly through its range of motion...   see if i get any reaction on the test light at all...

wait.. i see you have started a new thread.. i will continue there...  

Jim Riggs Jim Riggs
New User | Posts: 1 | Joined: 01/13
Posted: 01/20/13
02:03 PM

I have the same truck and it quit running while driving on the highway. I have replaced the ignition coil and the pickup under the distributor. Had the Ignition Module checked. Tested fine. Even replaced the Spark Control Module. Still won't run. The parts store now says I may have a bad ECM. They are saying the only way to tell is to replace it and if it starts, that must be the problem. Any suggestions??  

waynep71222 waynep71222
Guru | Posts: 823 | Joined: 03/12
Posted: 01/20/13
06:18 PM

a few things...

DO YOU HAVE VOLTAGE TO THE RED Wire to the coil and the module...

i have had both the wires fatigue and fail and the ignition switches fail....

lets look at this wiring diagram...
92 S10 Ignition Wiring

on the right side center of the image see the pink wire from the ignition switch...

goes thru the coil and to the module.. you need to see if that wire has power in the RUN and CRANKING POSITION of the ignition key...

the module is actually inside the distributer as you know

broken wires... bad ignition switches...

more to come...  

waynep71222 waynep71222
Guru | Posts: 823 | Joined: 03/12
Posted: 01/20/13
08:48 PM

i have had to replace the 243, 244 and 254 connections before. those are AZ or wells numbers...

do you have spark from the COIL.. a nice bright BLUE snappy spark..  

do you have spark from the spark plug wires???

i have had the ignition rotors burn thru... sending the high voltage from the coil to the distributer shaft..

so you have power going into the red wire on the coil... do you have power on the pink wire going into the module..??  use a test light..


when you turn the key from OFF to ON.. can you hear the fuel pump run for 2 seconds?????

i have also lost a lot of fuel pumps...  if you don't hear it turn on for 2 seconds..  you could have a fuel pump or a fuel pump power supply issue..

you could also have a ground loss issue for the pump.. the engine.. the ECM...  

waynep71222 waynep71222
Guru | Posts: 823 | Joined: 03/12
Posted: 01/20/13
09:06 PM

testing the ECM...


find the ALDL under the dash board...

jump the A and B terminals...  


turn on key, ENGINE OFF, KEY ON.... does the check engine light flash code 12 three times..


code 12 shows that the computer is awake..

post any other codes you get...

if you don't get a code 12 .. there are several pages of trouble shooting diagrams/flow charts to follow.. that are called... WON'T flash code 12.

please check the various fuses under the dashboard..

ECM 1   ECM 2   fuel pump... injector 1 and 2..  there are several... names vary..

if you get power at one side of the fuse..  you should get power at the other side of the fuse when you probe with a test light/circuit tester..

please... if you are blowing out fuses.. please post.. exactly which one. or take a photo of the fuse box and note the location...  with a year and that i can tell you what each fuse does..  

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