Ignition module issue - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Jmoney01 · 07-04-2020, 04:51 PM

My girl has been sleeping peacefully in the garage for a few years. Finally got around to messing with her. Now that she's running again, I'm stumped. It is burning up ignition modules almost daily. I have 12 volts to the hei only when key is on. What would cause these to pop? Maybe the truck doesn't like being out in the sun? Any ideas?

**Sheepdip** · 07-04-2020, 05:10 PM

It's possible your coil is bad. It heats up and shorts out making you think it's the module. Have you tried putting one of the burnt modules back in to see if it fires up? Once the coil cools down it works again for a little while and while you are putting a new module in it's cooling down only to fire up making you think you solved the issue.

Jmoney01 · 07-04-2020, 05:32 PM

I've let it sit for a few days between it running and then won't fire. Should be plenty of time to cool off, right?

toolboxchev · 07-04-2020, 05:40 PM

Check the wiring coming out of the HEI, The wires from the module circuit are know to get pinched by tuning on the manifold.

Also use a DVOM to get the actual voltage at the battery, both running and not.

HEI's modules do not like over voltage issues at all. The came out in congunction with the internally regulated alternator.

Here are the finer facts about the HEI and how to diagnose issues:http://www.crankshaftcoalition.com/w...EI_distributor

**Steeveedee** · 07-04-2020, 06:03 PM

Are you certain that you have the internal ground strap installed? The one that goes under the coil. If left out, you will get this symptom.

BROWN 70 · 07-04-2020, 06:55 PM

hi guys, are you putting heat sink compound under the module? when i bought my hei from summit, there was not any under the module. put some on and havent had a problem so far. 3-4 years. also check the ground as stated above, good luck. BROWN 70

**Boog** · 07-04-2020, 07:08 PM

I strongly suggest buying AC Delco modules over any others.

Jmoney01 · 07-04-2020, 07:51 PM

The coil ground is attached. I'm sure of that. I have spare hei's, might try just swapping out the whole thing...

**Sheepdip** · 07-04-2020, 08:12 PM

Quote:

Originally Posted by Jmoney01

I've let it sit for a few days between it running and then won't fire. Should be plenty of time to cool off, right?

Yep that's plenty! So it's probably not the coil itself.

**'68OrangeSunshine** · 07-04-2020, 08:35 PM

You can pull your Module and get it tested at any FLAPS. I carry a spare, known-good Module in the glove box of both trucks w/HEI. A new one averages about $15. Easy swap in the field as a troubleshooting step.
Fresh Module, still no-start?
OK, Coil?
Fuel Pump?
Etc.
Unlike points, you won't have to reset timing.

**HO455** · 07-04-2020, 08:36 PM

Lots of information in this recent thread that may help you.

https://67-72chevytrucks.com/vboard/...d.php?t=806473

07-04-2020, 04:51 PM	#1
Jmoney01 Registered User Join Date: Dec 2018 Location: Borden Posts: 97	Ignition module issue My girl has been sleeping peacefully in the garage for a few years. Finally got around to messing with her. Now that she's running again, I'm stumped. It is burning up ignition modules almost daily. I have 12 volts to the hei only when key is on. What would cause these to pop? Maybe the truck doesn't like being out in the sun? Any ideas?

07-04-2020, 05:10 PM	#2
Sheepdip Senior Member Join Date: Nov 2018 Location: Waterford California Posts: 2,626	Re: Ignition module issue It's possible your coil is bad. It heats up and shorts out making you think it's the module. Have you tried putting one of the burnt modules back in to see if it fires up? Once the coil cools down it works again for a little while and while you are putting a new module in it's cooling down only to fire up making you think you solved the issue.

07-04-2020, 05:32 PM	#3
Jmoney01 Registered User Join Date: Dec 2018 Location: Borden Posts: 97	Re: Ignition module issue I've let it sit for a few days between it running and then won't fire. Should be plenty of time to cool off, right?

07-04-2020, 05:40 PM	#4
toolboxchev Registered User Join Date: Jul 2015 Location: 2nd left past the stump on a dirt road. Posts: 2,629	Re: Ignition module issue Check the wiring coming out of the HEI, The wires from the module circuit are know to get pinched by tuning on the manifold. Also use a DVOM to get the actual voltage at the battery, both running and not. HEI's modules do not like over voltage issues at all. The came out in congunction with the internally regulated alternator. Here are the finer facts about the HEI and how to diagnose issues:http://www.crankshaftcoalition.com/w...EI_distributor

07-04-2020, 06:03 PM	#5
Steeveedee Who Changed This? Join Date: Jan 2013 Location: Simi Valley, CA Posts: 10,677	Re: Ignition module issue Are you certain that you have the internal ground strap installed? The one that goes under the coil. If left out, you will get this symptom. Attached Images __________________ ~Steven '70 Chevy 3/4T Longhorn CST 402/400/3.56 Custom Camper Simi Valley, CA Last edited by Steeveedee; 07-04-2020 at 06:10 PM.

07-04-2020, 06:55 PM	#6
BROWN 70 Registered User Join Date: Aug 2010 Location: central oregon Posts: 157	Re: Ignition module issue hi guys, are you putting heat sink compound under the module? when i bought my hei from summit, there was not any under the module. put some on and havent had a problem so far. 3-4 years. also check the ground as stated above, good luck. BROWN 70

07-04-2020, 07:08 PM	#7
Boog laying low Join Date: Mar 2001 Location: Searcy, Ark. USA Posts: 13,514	Re: Ignition module issue I strongly suggest buying AC Delco modules over any others. __________________ Boog 69 Chevy stepside, 358/T350, 4.11 posi, 4.5/4 drop, rallys, poboy driver primer is finer 91 Chevy sportside, Tahoe, Yukon & GMC Crewcab All GM..'nuff said. I stand for the flag and kneel at the cross

07-04-2020, 07:51 PM	#8
Jmoney01 Registered User Join Date: Dec 2018 Location: Borden Posts: 97	Re: Ignition module issue The coil ground is attached. I'm sure of that. I have spare hei's, might try just swapping out the whole thing...

07-04-2020, 08:35 PM	#10
'68OrangeSunshine Senior Member Join Date: Feb 2002 Location: Tucson, AZ USA Posts: 7,504	Re: Ignition module issue You can pull your Module and get it tested at any FLAPS. I carry a spare, known-good Module in the glove box of both trucks w/HEI. A new one averages about $15. Easy swap in the field as a troubleshooting step. Fresh Module, still no-start? OK, Coil? Fuel Pump? Etc. Unlike points, you won't have to reset timing. __________________ Every 25 years I like to rebuild that 292, whether it needs it or not.

07-04-2020, 08:36 PM	#11
HO455 Post Whore Join Date: Feb 2016 Location: Portland Oregon Posts: 11,350	Re: Ignition module issue Lots of information in this recent thread that may help you. https://67-72chevytrucks.com/vboard/...d.php?t=806473 __________________ Thanks to Bob and Jeanie and everyone else at Superior Performance for all their great help. RIP Bob Parks. 1967 Burban (the WMB),1988 S10 Blazer (the Stink10 II),1969 GTO (the Goat), 1970 Javelin, 1952 F2 Ford OHC six 4X4, 29 Model A, 72 Firebird (the DBP Bird). 85 Alfa Romeo If it breaks I didn't want it in the first place The WMB repair thread http://67-72chevytrucks.com/vboard/s...d.php?t=698377



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