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12-07-2022, 01:45 PM | #1 |
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Join Date: Aug 2012
Location: Parrish, FL
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Ignition Control Module Issues on my 71
I've recently run into an issue with ignition control module failures on my 71 C10. I've done some online searching but haven't found anything that really outlines how to troubleshoot and solve the issue. Hoping someone can point me in the right direction.
Now the details - 71 C10, purchased a year ago, SBC with aftermarket HEI distributor, aftermarket 8mm plug wires. I put about 10k miles on it without issue, however in the last 2 months and appx 1000 miles I have experienced ignition control module failures twice. About 3 months ago I installed Dakota Digital HDX gauge cluster and wired up the tachometer, prior to that there was no tach. After the first failure I inspected the tach wire and connections and replaced the cap and rotor. Also installed a Pertronix Flame Thrower module as I read they were "more robust". Just lost that module the other night driving down the road at 30-40 mph, engine backfire and shutdown. I was able to restart and make it a few more miles before it failed for good. I replaced it roadside with a spare and it started right up. First failure was the same except after first shutdown and restart the tach was reading 0. I've reached out to Dakota Digital, can't imagine that's the issue but that seems to be when my issues started. Any suggestions or guidance on how to troubleshoot further? What impedance/resistance should I see at the tach wire at the distributor?
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58 Fleetside 71 Cheyenne |
12-07-2022, 04:44 PM | #2 |
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Re: Ignition Control Module Issues on my 71
Are you putting the heat paste under the module when installing?
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12-07-2022, 10:25 PM | #3 |
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Re: Ignition Control Module Issues on my 71
Yes I am. First one I inherited from previous owner but it had the thermal compound. The Pertronix I used to replace it came with white thermal paste which I used. The one I just put in is an old Delco Remy, comes with the clear paste which I used.
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58 Fleetside 71 Cheyenne |
12-08-2022, 07:28 PM | #4 |
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Re: Ignition Control Module Issues on my 71
I'm pretty sure there is no such thing as clear thermal paste. That is probably dielectric grease for the terminals only, which won't work as a thermal compound.
Just curious, have you tried just disconnecting the tach wire at the distributor and see if the problem the module seems to be causing goes away? The tach wire shorting to ground is a method of making a kill switch, it will disable the spark, so a bad tach or bad wire shorted to ground, or intentional short to ground will disable the engine. I mention this because you indicate tach is new to the truck and you didn't have problems before it. |
12-09-2022, 01:08 PM | #5 |
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Location: So Cal
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Re: Ignition Control Module Issues on my 71
Do you have anything connected to the "R" terminal on the starter solenoid? If you do, remove it. Fold the wire back on itself and tape it up.
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'67 GMC 2500, 292, 4spd, AC |
12-10-2022, 05:24 PM | #6 |
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Re: Ignition Control Module Issues on my 71
Are you using the stock resistor wire to the distributor? The lower voltage from that wire will cause more current through the module.
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Richard 1972 K10 Custom Deluxe SWB Fleetside My build https://67-72chevytrucks.com/vboard/...d.php?t=800746 |
12-11-2022, 03:09 PM | #7 | |
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Re: Ignition Control Module Issues on my 71
Quote:
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58 Fleetside 71 Cheyenne |
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12-11-2022, 03:22 PM | #8 |
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Re: Ignition Control Module Issues on my 71
Thanks for the suggestion, I replaced the starter almost a year ago with a Powermaster mini, the wire for the R terminal was removed then.
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58 Fleetside 71 Cheyenne |
12-12-2022, 06:17 PM | #9 |
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Re: Ignition Control Module Issues on my 71
Richard,
>>The lower voltage from that wire will cause more current through the module.<< NOT TRUE. If you increase the resistance in a Series Circuit, it reduces the current.
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'67 GMC 2500, 292, 4spd, AC |
12-13-2022, 01:17 AM | #10 |
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Re: Ignition Control Module Issues on my 71
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VetteVet metallic green 67 stepside 74 corvette convertible 1965 Harley sportster 1995 Harley wide glide Growing old is hell, but it beats the alternative. |
12-15-2022, 11:05 PM | #11 | |
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Re: Ignition Control Module Issues on my 71
Quote:
Follow this link to Wikipedia: https://en.wikipedia.org/wiki/Resist...20other%20uses. |
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12-17-2022, 10:40 AM | #12 |
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Re: Ignition Control Module Issues on my 71
it does have the ground strap that bolts to the coil right?
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88 military v30 crewcab shortbed 5.9 cummins, nv4500, 205 86 k30, 89 diesel burb, 76 gmc pathfinder 71 longbed 5.3 4l80 http://67-72chevytrucks.com/vboard/s...d.php?t=522535 |
12-17-2022, 06:54 PM | #13 |
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Re: Ignition Control Module Issues on my 71
Yes it does.
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58 Fleetside 71 Cheyenne |
12-17-2022, 07:00 PM | #14 |
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Re: Ignition Control Module Issues on my 71
I went ahead and purchased some good thermal paste, cleaned the other stuff out and applied to the old Delco Remy. Inspected all the wiring for cracks or damage, everything looks good. Checked the ground back to the battery, 0.3 ohms should be more than good enough. I went ahead and disconnected the tachometer wire as an experiment since I don't really see anything else that could be causing the problem.
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58 Fleetside 71 Cheyenne |
12-18-2022, 03:21 AM | #15 |
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Re: Ignition Control Module Issues on my 71
Was thinking of brown out situations volts X amps equals watts. Lots of fuses and circuit boards replaced in my career due to low voltage. A device wants a certain amount of watts to operate. If volts drop, amps will typically increase. Did not consider the resistance. None the less, operating a load outside of rated specs causes inefficiency's, added stress. heat and early failure. Guessing OP has addressed this as there has been no mention of changing the wire.
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Richard 1972 K10 Custom Deluxe SWB Fleetside My build https://67-72chevytrucks.com/vboard/...d.php?t=800746 Last edited by Richard; 12-18-2022 at 03:54 AM. |
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