Eating ignition modules. Need advice.

[turbomatt]

i don't post much on here since everything i could possibly need to know has already been posted. anyway, over the past week i have become a pro at changing ignition modules. the first one was in the distributor i installed when i first bought the truck. that was four months ago. never gave me a problem until this past tuesday. got on the highway and as soon as i got up to speed it was like i turned the switch off. had it towed home and figured out the module was bad. so i put a spare in and drove it the rest of the week. friday, i went to GM and bought the proper module and installed it. the truck ran like a million bucks. then saturday night (yesterday) it just died out of the blue again. same problem. since it killed the GM module i am leaning towards a wiring problem. i have inspected the wires coming from the module going into the main harness. nothing. maybe i missed something. anyway, it has a stock coil and taylor wires, ngk tr6's, and a fast box. does anybody have a clue as to where i might start to look for a problem. no blown fuses, pump primes and runs, c-com for fast box shows rotation when cranking with a dead module. lemme know what you guys think.

matt

 

[s_blazin]

Re: Eating ignition modules. Need advice.

i had an epidemic of this a couple years ago, i bought one from an auto parts store with a 5 year, good thing i did i replaced it 7 times that year alone.

i asked a guy i know that owned a local hotrod and repair shop and he said he was getting killed with customer tow backs from modules going bad, NEW GM and AFTERMARKET both were just going out left and right.

i ended up putting my truck into the shop for some other things and have not driven it since so i do not know if mine is another BAD one but he said he has not had to pay a towing bill for a customer return for about 2 years now.

make sure when you install a new one use all the dialectric grease you can on the darn thing, i think thats why i had a prblem with the first 1 or 2 but the rest i used it and they were still going bad.

so it is possible there's just another bad batch produced

 

[Osmosis]

Re: Eating ignition modules. Need advice.

It's gotta be a short of some sort. Ignition mod's are electrical components and they rarely go bad. The only thing that can cause them to go bad would be a short or a bad ingition component...check your coil and distributor.:myclone:

 

[JSM]

Re: Eating ignition modules. Need advice.

I know of a truck that has eaten a few also, so be curious to see if anybody finds a real reason besides maybe crappy modules.

 

[Daron]

Re: Eating ignition modules. Need advice.

I know of a truck that has eaten a few also, so be curious to see if anybody finds a real reason besides maybe crappy modules.

Mine has "munched" a few. Its not the pick up coil in my case, Distributor was replaced just prior to the latest.

 

[Ry368]

Re: Eating ignition modules. Need advice.

My old Ty had this problem. I finally ended up pulling the distributor and found the cam gear was worn bad...almost razor sharp....replaced gear and all was fine.

 

[gmcturbo]

Re: Eating ignition modules. Need advice.

all an ignition module does is turn on and off primary current flow through the ignition coil. if you keep frying your ignition module the ignition coil is likely shorted. using an ohmmeter is not a good test you need to look at the current flow with a low amp probe and a labscope. replace your ignition coil and use gm parts.

mike

 

[turbomatt]

Re: Eating ignition modules. Need advice.

ok, so i left out some stuff. brand new coil as of last wednesday. brand new distributor as of 4 months ago so no drive gear problem and i would certainly hope no pick up coil problem. i use ALL of the grease that comes with each module and i wipe the mating surface clean on the distributor base every time i install a new one. i have been going since saturday night on the current one and have a tool kit consisting of a small battery screwdriver, a flex shaft for the 1/4 inch drive, the proper socket for the cap and module, and a regular screwdriver for reinstalling the module (so i don't kill it with the power driver). i'll ohm the pickup anyway, but i would think if it was a short i would kill a lot more. the truck has been lowered since before i bought it. so with the back bounching off the bump stops more than enough plus the substandard paving that north carolina is notorious for, a short should kill a module every five minutes. there is no missfire, and the only hesitation i get is when i drive it while it is warming up due to some part throttle tuning that hasn't been done yet.

 

[gmcturbo]

Re: Eating ignition modules. Need advice.

maybe you mis-understood me. i meant shorted as lower than oe resistance. not a direct short to ground. the only reason you are going thru so many modules is because the ignition coil has too low resistance. an ohm meter will not show you this. it doesnt matter if the coil is brand new. a pick up coil will never damage an ignition modue.

we are talking a brand new gm module not like autozone or whatever right?

 

[cameronsclone]

Re: Eating ignition modules. Need advice.

i went through one in a week when i forgot to apply the gel that came with it. its supposed to dissipate heat and i guess the heat got to mine.

 

[turbomatt]

Re: Eating ignition modules. Need advice.

i am for sure that it is the module dying rather than a random open/short in the pickup coil. i reinstalled a supposedly dead module last night and it was still dead. so it's eating modules, and the last module it ate was an AC Delco purchased from one of the local chevy dealers. by the way, the first module died before the coil was replaced. i would think that would remove the coil from the equation but maybe not. i am gonna take a chance and if it eats another one the harness is coming out of the truck, untaped, and inspected.

 

[gmcturbo]

Re: Eating ignition modules. Need advice.

And the pick-up coil can be checked with an ohmmeter.

Regards,
Dave

it cannot tell you if the coil can produce the proper voltage. its really not a good test. ac voltage scope trace is the only good way to test; trust me. what if it ohms at spec but only produces 1V peak to peak?

youre right about the pick up coil though, it can lead some people to think the ig. module is bad when its not.

 

[turbomatt]

Re: Eating ignition modules. Need advice.

i can tell you exactly what will cause a truck to eat ignition modules.* when the fumble fingered owner pinches the pick up coil wires between the distributor cap and the distributor base.* instant short every time. :doh::banghead::slap:

 

[4C FED]

Re: Eating ignition modules. Need advice.

I caught that happening a couple of times myself. Fortunately before I tightened the cap down.

 

[turbomatt]

Re: Eating ignition modules. Need advice.

well. my last distributor the wires were just long enough to make it to the module so it didn't even cross my mind that these would reach far enough to get under the cap.

 

[Daron]

Re: Eating ignition modules. Need advice.

i can tell you exactly what will cause a truck to eat ignition modules.* when the fumble fingered owner pinches the pick up coil wires between the distributor cap and the distributor base.* instant short every time. :doh::banghead::slap:

Good call, glad to hear you ran it down!

 

[Quickstop [UK]]

Re: Eating ignition modules. Need advice.

So now it's running good?

 

[turbomatt]

Re: Eating ignition modules. Need advice.

thanks for the help guys. and by the way, the testosterone induced, pi$$ing contest "you idiot you should have listened to me" comments can be left well enough alone. just because i'm a new member to this particular forum doesn't mean i haven't been around quite a while. every ignition module i changed i did by feel. my short a$$ can't get up high enough to see all the wires back there. i finally noticed the problem when i climbed on top of the engine with my chin on the plenum and looked straight down at the distributor. and all the modules that were removed were indeed bad. i pulled out my spark tester and checked all the ones in question. so it's fine now. just don't assume a newb to a forum is a newb to cars. i have been a senior member and moderator on several car forums and have always followed the simple system of "if you have no good usable input, you might as well have no input at all." myself and my buddy christian in orlando labored many long nights on this truck years ago before i even thought about buying it. :tup:

thanks
matt