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No spark Montana

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10 Feb 2019 17:26 - 10 Feb 2019 17:27 #26948 by wcarrothres
No spark Montana was created by wcarrothres
Hello..

99 Montana Pontiac 3400 v6 motor / mini van. Stalled out while driving turns over fine but will not start. Watched the How to test a GM ignition module (crank sensor bypass test) which was helpful but have some other issues which confuse.

Could not trick the module to fire/spark with the T pin test on the crank sensor input wire & test light (like the video)

And continued to diagnose and found the power input connector measures ground on both wires ign on.

So have diagnosed the problem thus far as the ign module not being properly powered up when the key is on. So makes sense I would be in a no spark situation here.

Ign relays and fuses appear to be fine

With an external separate connector wired to battery and ground plugged to the power input of the ign control module restores spark while cranking. So believe the module and coils are fine based on that. But am still in a no start situation. even with the module "hot wired" to power.

From what I can see while operating the module with the fly leads to power it, the fuel pump does cycle when the key/ignition is turned on. And I am getting fuel pressure.. So assume now I am not getting fuel and something related to or that shares the Ign module power input maybe effecting injectors/fueling

Looking for a suggestion of where to look next in a situation like this where both power wires power to the ignition module seems to be grounded.

Only module code is a P0043 Evap Emission System purge control valve circuit. Don't know if that would point in any direction. might mean something if power for that was also shared by the Ign control module but figured worth mention

Thanks if any one has any suggestions..
Last edit: 10 Feb 2019 17:27 by wcarrothres.

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10 Feb 2019 18:45 #26949 by Letounreau86
Replied by Letounreau86 on topic No spark Montana
I read that you hear the fuel pump turning on.. but not that you actually have fuel pressure.. I would hook a fuel gauge up to be 100 percent sure.. now for the power feed of ICM. Fix your
Power feed which is your pink wire from the wiring diagram and the fuse is the elek ING fuse .and also check white wire which is an ignition control wire. Double check your ground connection(loaded) at ICM. Then you may need to check your 3x and 24x signals.

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10 Feb 2019 19:16 #26950 by wcarrothres
Replied by wcarrothres on topic No spark Montana
Thanks for the suggestions..

Yes technically I have not double checked my fuel pressure with gauge. So will add that to the list. when it died, it didn't die as if it was starving for fuel it pretty much just died like it turned off and such.

I will look at the items you suggest. Figured might be some combination with what I was seeing wiring wise (no power to the Ignition module). Thought I would be able to work around it powering the module independent and at least got spark back But obviously losing proper power to the ign control module also means something else isn't getting powered.

I'll poke around the wiring you suggest. I did pull and re-install the x24 crank sensor behind the crank pulley years ago doing other work to the car. but thought the sensor in the block had more to do with timing stuff then the one behind the crank..

I'm probably going to be chasing a wiring gremlin which is never fun

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10 Feb 2019 19:37 - 10 Feb 2019 19:45 #26951 by Letounreau86
Replied by Letounreau86 on topic No spark Montana
I completely agree with you that in most cases the 24x will not keep the vehicle from running or starting.. with that being said.. I had a 2000 impala 3.4 that would stall intermittently... And then not restart... I hooked my scope up to both signals when this happened and the 24x had no signal while my 3x was good... So replaced the 24x and client never returned with that issue.. so just have an open mind and believe that in automotive electronics. That the impossible is possible. Now keep in mind that the 24x is used to control idle and other things at low Rpms. So it is possible that a faulty 24xsensor will keep the vehicle from starting depending on how it fails..
Last edit: 10 Feb 2019 19:45 by Letounreau86. Reason: Forgot to add

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11 Feb 2019 09:38 #26956 by Tyler
Replied by Tyler on topic No spark Montana
wcarrothres, I see that you've jumped direct B+ to the pink wire at the ICM, correct? Where are your other jumpers connected, exactly? You mention both power wires at the ICM being 'grounded', but there's only one power feed that I'm aware of.

For our info, what are you using to do your testing? A Power Probe?

When you said you checked the fuses and found them good, how did you check them? I ask because the ELEK IGN (which is the ICM power feed), INJ, TCC, IGN 1 U/H and A/C CLU are all powered by the IGN MAIN relay. It'd be valuable to know if all those fuses are powered with the key on. Sorry if you've checked this, just wanna be clear! :cheer:

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11 Feb 2019 10:11 - 11 Feb 2019 10:13 #26959 by wcarrothres
Replied by wcarrothres on topic No spark Montana
Thanks for the reply. Believe me I'm looking for any help I can with this so will clarify what ever I can to try to give a better picture..

So when testing the A and B power input to the IGN controller (pink isa and black wires) they both test to ground with a digital test lamp. And if I use a standard meter black to pink I measure 0 voltage when key on.

When I'm describing powering the unit my self, I'm doing that with a separate connector plugged into the Ign control power input plug with the wires alligator clipped to battery and ground. Doing this to verify I'm getting spark when turning over the motor.

So the pink and black connector in the wire harness was disconnected during this test.

Since the unit wasn't being powered from the harness properly from what I could see I gave that a try.

Fuses were checked visually and with test lamp but. I did hop around the fuses in your list with key on with the test lamp and from memory don't recall anything weird.
I believe the IGN relay is functioning properly when key on but will add your list of items to my list to double check

at this point facts I have is, no power to IGN module from harness connector and get no spark.

If I hotwire the IGN module to power, I can restore spark.

But something related to no power to IGN module is probably causing me at this point to have no injector pulses (I have not verified injector signals but it's on my list)

my original thought was I had no spark but also turns out I probably have no spark and no fuel.

Pump is running but need to check fuel pressure. poping the fuel valve on the rail looks like I have plenty of pressure but understand is a crude way to verify that.
Last edit: 11 Feb 2019 10:13 by wcarrothres.

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11 Feb 2019 12:05 #26963 by Tyler
Replied by Tyler on topic No spark Montana

wcarrothres wrote: So when testing the A and B power input to the IGN controller (pink isa and black wires) they both test to ground with a digital test lamp. And if I use a standard meter black to pink I measure 0 voltage when key on.

When I'm describing powering the unit my self, I'm doing that with a separate connector plugged into the Ign control power input plug with the wires alligator clipped to battery and ground. Doing this to verify I'm getting spark when turning over the motor.

So the pink and black connector in the wire harness was disconnected during this test.


So you depinned the ICM connector and inserted your own jumpers into the pin cavities for the main ICM power and ground? No problem if this is what you did, just wanna be certain.

Fuses were checked visually and with test lamp but. I did hop around the fuses in your list with key on with the test lamp and from memory don't recall anything weird.
I believe the IGN relay is functioning properly when key on but will add your list of items to my list to double check


No problem, let me know what you find. :) I like the IGN MAIN relay theory, since it neatly explains your symptoms. But, I could be way off. :silly:

But something related to no power to IGN module is probably causing me at this point to have no injector pulses (I have not verified injector signals but it's on my list)

my original thought was I had no spark but also turns out I probably have no spark and no fuel.

Pump is running but need to check fuel pressure. poping the fuel valve on the rail looks like I have plenty of pressure but understand is a crude way to verify that.


This is why I suspect an IGN MAIN relay issue, as the same relay supplies the power for the fuel injectors. That'd account for the (seemingly) good fuel pressure but no start.

The power distribution diagram might help anyone following along. The fuses we're after are on page #2:

File Attachment:

File Name: montanapow...tion.pdf
File Size:581 KB


If those fuses check out for power with the key on, then I'd suggest moving to C102 to check for injector power and control. For clarity:



C102 is the bulk connector that contains all six injector control wires, plus the injector power feed. C102 is usually on the firewall side of the upper intake plenum, near the alternator. Find the solid pink wire (pin D), and check it for power KOEO and backprobed.
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11 Feb 2019 12:35 #26967 by wcarrothres
Replied by wcarrothres on topic No spark Montana
Thanks for the diagrams and such. I will step through things as suggested and let ya know.

Far as powering the IGN module, I used a matching connector I had on the shelf to plug in and create the fly leads. So a little cleaner a job then just clipping in. Figured if it ended up the "answer" i could live with a separate switch to activate it short term while I sorted out the problem But of course with no fuel that idea went out the window.

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