Ignition switch getting hot! - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Nick2x2x · 10-10-2021, 08:38 PM

Have a 1970 C10 LSSwap with American Autowire wiring harness noticed this weekend that hot wire is getting extremely hot. Anyone have any idea why this may be happening?
Posted via Mobile Device

**davischevy** · 10-10-2021, 08:47 PM

Quote:

Originally Posted by Nick2x2x

Have a 1970 C10 LSSwap with American Autowire wiring harness noticed this weekend that hot wire is getting extremely hot. Anyone have any idea why this may be happening?
Posted via Mobile Device

Check your grounds.

**LockDoc** · 10-11-2021, 09:57 AM

-
Like Larry said the grounds would be a good place to start. Here is a good thread on the ground strap locations. They are really important on these trucks.

http://67-72chevytrucks.com/vboard/s...d.php?t=422234

It could also be a weak ignition switch or dirty terminals on the switch its self.

LockDoc

body bolt · 10-11-2021, 10:42 AM

Like LockDoc said, I'd check the switch. Bad grounds wouldn't cause the hot wire to get hot.

HotWheelsFan · 10-11-2021, 11:03 AM

Heat comes from resistance, usually...

A poor connection from the wires to the switch, through the connection or the terminals. Worn switch causing poor connections internally. Problem could be elsewhere in the circuit as well, allowing added current through the switch.

I have seen these common problems with older vehicles as rust and corrosion attacks electrical systems. A little resistance at every terminal adds up.

Maybe amp draw testing or voltage drop testing could help pinpoint where the problem is.

Bob

fun in dirt · 10-11-2021, 11:39 AM

Check the connectors in the plug that goes into the switch. As much as I like American Autowire, the last ign switch connector I got in a kit had a loose terminal that almost caused a big problem.

**HO455** · 10-11-2021, 03:04 PM

Here is a thread on ignition switch issues I have experienced.
I would suggest doing amperage checks on individual conductors with a clamp on style ampmeter. Only turning the power on long enough to get a reading then power off before changing conductors. You want to avoid damaging anything. Start with the power supply to switch.
Something is drawing too much amperage! It could be from a bad ignition switch or as this is a new installation there may be a wire that is somehow partially grounded causing the increased amp draw.
Don't assume that the harness or any other new component is not at fault. AAW makes good products (Heck I have an AAW harness on my Burban.) but, anybody can have a bad day.
Does the problem occur in both ON and ACC? Or is it in START only? Answering these should help us help you find the problem.
Do you know if the harness uses the original color coding the factory used ?

https://67-72chevytrucks.com/vboard/...d.php?t=818861

Good luck and keep us posted.

**Wrenchbender Ret** · 10-11-2021, 05:02 PM

It is common on these trucks. You are going to have to replace the switch & connector pigtail. They are readily available. Do you know how to remove the tumbler from the switch? The best way to connect the wires to the pigtail is solder & heat shrink tubing.
George

**BigBird05** · 10-11-2021, 08:25 PM

If you have a new ign switch it could be at fault. They are not made as well as the original switch. They can over heat easely. Best to use some relays to protect your wireing.

HotWheelsFan · 10-12-2021, 11:59 AM

I'm not sure about soldering the terminals, just a good crimp tool secures the wires fine.

I have tried soldering terminals on one of my projects and had problems with corrosion. It seems the flux in the solder eats away the plating on some terminals allowing corrosion to start.

I have seen posts about pros and cons of soldering automotive terminals.

Just a thought...

Bob

MARKDTN · 10-12-2021, 01:15 PM

The AAW kits appear to have a new plug so not sure why you would have to replace it? Even so they are probably type 56 connectors. You can buy the terminals and crimp them on if needed-assuming you have enough wire length. That would avoid a splice. Are you exceeding the current capacity of the wiring? If you have a lot of high amp stuff you may need to supply them using relays that (fused) powered direct to battery and are triggered by an ignition source so you can take load off that ignition switch. But I would start with grounds. Proper grounds are so important and so often overlooked.

toolboxchev · 10-12-2021, 10:42 PM

Is it when the heater is running?

The heater circuit runs through the ignition switch. If you have an AC heater fan which will draw 30 amps or so on high without the AC wiring and relay this could be the culprit.

GM did some funny stuff and now nobody supplies a 10 or 15 amp heater only fan. The parts houses just substitute the AC fan for heater only applications. Ask me how I know, I had to completely rebuild my stock wiring harness due to this, plus switches, plugs and all kinds of stuff.

Nick2x2x · 10-18-2021, 09:10 AM

Sorry Its taken me a while to respond been out of town!

So I noticed it while driving after a while. Pulled my key out it was hot as fire but then payed attention a little more.
No electronics were on except radio. Later that evening I just ran the truck and the switch was still getting hot. Going to reach out to AAW about the switch I haven't done a whole bunch of trouble shooting on it since it is a fresh build with about 1900 miles. For Cruisin the Coast was the longest and the most i driven it at one time which may be why i noticed it there

Accelo · 10-18-2021, 10:39 AM

American Autowire has so many options and places that supply power to other circuits it is impossible to tell what may be going on for sure. You might start with an amp meter on the supply circuit for the switch. I wouldn't blame American Autowire or there products till some basic testing, by someone that know how to troubleshoot electronic circuits, has been completed.

**71CHEVYSHORTBED402** · 10-18-2021, 11:50 AM

Might help....Not "tested" so to speak, I need to install one yet. 1971 with HEI.....

If you haven't already, personally I'd swap out the switch for starts.

**BigBird05** · 10-18-2021, 05:21 PM

I have torn down original GM switches that are 50+ years old and found that with age the grease gets almost solid and the contact surface between the rotating part of the switch and the fixed contacts that the wires connect to can become very burnt making for a lot of resistance. Enough to melt the connector on the back.

**HO455** · 10-18-2021, 09:08 PM

Quote:

Originally Posted by Nick2x2x

Sorry Its taken me a while to respond been out of town!

So I noticed it while driving after a while. Pulled my key out it was hot as fire but then payed attention a little more.
No electronics were on except radio. Later that evening I just ran the truck and the switch was still getting hot. Going to reach out to AAW about the switch I haven't done a whole bunch of trouble shooting on it since it is a fresh build with about 1900 miles. For Cruisin the Coast was the longest and the most i driven it at one time which may be why i noticed it there

If you're still driving the truck I certainly hope you have a good fire extinguisher and a battery disconnect on your truck. Problems like this don't just go away. They flare up in a bad way at the worst time.
Pun intended.

Accelo · 10-19-2021, 12:24 AM

Quote:

Originally Posted by BigBird05

I have torn down original GM switches that are 50+ years old and found that with age the grease gets almost solid and the contact surface between the rotating part of the switch and the fixed contacts that the wires connect to can become very burnt making for a lot of resistance. Enough to melt the connector on the back.

The kit comes with a new switch.

Nick2x2x · 10-19-2021, 06:22 AM

Quote:

Originally Posted by HO455

If you're still driving the truck I certainly hope you have a good fire extinguisher and a battery disconnect on your truck. Problems like this don't just go away. They flare up in a bad way at the worst time.
Pun intended.

No sir haven't driven it at all been busy with work so haven't had much time to troubleshoot.

**HO455** · 10-19-2021, 03:05 PM

Quote:

Originally Posted by Nick2x2x

No sir haven't driven it at all been busy with work so haven't had much time to troubleshoot.

Oh good! Your post made me think you had been driving it around.
I definitely understand work taking over ones life.
Good luck when you get time to tear into it. And please post your findings.

**BigBird05** · 10-19-2021, 03:23 PM

Dose the switch get hot with the ignition on but not running?

**StingRay** · 10-20-2021, 02:12 PM

I found out the hard way that a replacement heater motor drew far more current than stock. At first I was thrilled that it would blow a pop can off of the dash. Excellent defrost. Eventually that current draw through the ignition switch caused a melt down.

Nick2x2x · 10-21-2021, 07:25 AM

UPDATE!!!!!!!!

Was able to do a little investigation!

I used the The ignition Wire (pink) in the AAW wiring harness to feed the Electric fans due to the fans (supposedly) only using 8amps to run! which would have put me at 16 amps total on a a 12ga. wire (rated for 20 amps). Well I have determined that was a LIE! I will be separating the fan feeds and putting 2 inline fuses in and connecting them to the battery link box!

Thank you all for the help glad to be a part of this family!

Accelo · 10-21-2021, 07:58 AM

Glad you identified the issue. Typically fans are powered through relays. This removes the load from the control circuits.
Cheers.

Nick2x2x · 10-21-2021, 01:06 PM

Quote:

Originally Posted by Accelo

Glad you identified the issue. Typically fans are powered through relays. This removes the load from the control circuits.
Cheers.

Its actually running through a relay but I pulled the power from a circuit that can't handle the load so I will be going directly to a power source stud

10-10-2021, 08:38 PM	#1
Nick2x2x Registered User Join Date: Mar 2017 Location: Loranger, LA. Posts: 51	Ignition switch getting hot! Have a 1970 C10 LSSwap with American Autowire wiring harness noticed this weekend that hot wire is getting extremely hot. Anyone have any idea why this may be happening? Posted via Mobile Device

10-11-2021, 09:57 AM	#3
LockDoc The Older Generation Join Date: Aug 2006 Location: Montezuma, Iowa Posts: 25,317	Re: Ignition switch getting hot! - Like Larry said the grounds would be a good place to start. Here is a good thread on the ground strap locations. They are really important on these trucks. http://67-72chevytrucks.com/vboard/s...d.php?t=422234 It could also be a weak ignition switch or dirty terminals on the switch its self. LockDoc __________________ Leon Locksmith, Specializing In Antique Trucks, Automobiles, & Motorcycles (My Dually Pickup Project Thread) http://67-72chevytrucks.com/vboard/s...d.php?t=829820 -

10-11-2021, 10:42 AM	#4
body bolt Registered User Join Date: Oct 2020 Location: Albuquerque, New Mexico Posts: 475	Re: Ignition switch getting hot! Like LockDoc said, I'd check the switch. Bad grounds wouldn't cause the hot wire to get hot.

10-11-2021, 11:03 AM	#5
HotWheelsFan Registered User Join Date: Mar 2010 Location: Oregon Posts: 185	Re: Ignition switch getting hot! Heat comes from resistance, usually... A poor connection from the wires to the switch, through the connection or the terminals. Worn switch causing poor connections internally. Problem could be elsewhere in the circuit as well, allowing added current through the switch. I have seen these common problems with older vehicles as rust and corrosion attacks electrical systems. A little resistance at every terminal adds up. Maybe amp draw testing or voltage drop testing could help pinpoint where the problem is. Bob __________________ 1970 C20 Long Bed Fleetside - Restoration My truck videos - Youtube

10-11-2021, 11:39 AM	#6
fun in dirt Registered User Join Date: Jan 2007 Location: Mississippi Posts: 2,117	Re: Ignition switch getting hot! Check the connectors in the plug that goes into the switch. As much as I like American Autowire, the last ign switch connector I got in a kit had a loose terminal that almost caused a big problem. __________________ '72 C to K20 "Cannibalizer" http://67-72chevytrucks.com/vboard/s...32#post8653432 '85 K30 "Big Nassy" '06 3500 Duramax ...tow truck '06 Silverado SS...DD '06 C1500 WT...DD '07 Classic C1500 WT...DD Built & sold cause can't keep 'em all: '72 Blazer "The Bucket" http://67-72chevytrucks.com/vboard/s...d.php?t=433190 '55 Chevy straight axle gasser https://www.trifive.com/forums/showthread.php?t=173938 '69 Pro Street Chevelle http://www.chevelles.com/forums/showthread.php?t=332541 '86 M1031 CUCV http://67-72chevytrucks.com/vboard/s...d.php?t=553619

10-11-2021, 03:04 PM	#7
HO455 Post Whore Join Date: Feb 2016 Location: Portland Oregon Posts: 10,786	Re: Ignition switch getting hot! Here is a thread on ignition switch issues I have experienced. I would suggest doing amperage checks on individual conductors with a clamp on style ampmeter. Only turning the power on long enough to get a reading then power off before changing conductors. You want to avoid damaging anything. Start with the power supply to switch. Something is drawing too much amperage! It could be from a bad ignition switch or as this is a new installation there may be a wire that is somehow partially grounded causing the increased amp draw. Don't assume that the harness or any other new component is not at fault. AAW makes good products (Heck I have an AAW harness on my Burban.) but, anybody can have a bad day. Does the problem occur in both ON and ACC? Or is it in START only? Answering these should help us help you find the problem. Do you know if the harness uses the original color coding the factory used ? https://67-72chevytrucks.com/vboard/...d.php?t=818861 Good luck and keep us posted. __________________ Thanks to Bob and Jeanie and everyone else at Superior Performance for all their great help. RIP Bob Parks. 1967 Burban the WMB,1991 S(stink)-10 Blazer,1969 GTO, 1970 Javelin, 1952 F2 Ford 4X4, 29 Model A, 72 Firebird. 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

10-11-2021, 05:02 PM	#8
Wrenchbender Ret Registered User Join Date: Oct 2005 Location: Overland Park, Ks. Posts: 5,190	Re: Ignition switch getting hot! It is common on these trucks. You are going to have to replace the switch & connector pigtail. They are readily available. Do you know how to remove the tumbler from the switch? The best way to connect the wires to the pigtail is solder & heat shrink tubing. George

10-11-2021, 08:25 PM	#9
BigBird05 Senior Member Join Date: Aug 2019 Location: Cheraw Posts: 1,305	Re: Ignition switch getting hot! If you have a new ign switch it could be at fault. They are not made as well as the original switch. They can over heat easely. Best to use some relays to protect your wireing.

10-12-2021, 11:59 AM	#10
HotWheelsFan Registered User Join Date: Mar 2010 Location: Oregon Posts: 185	Re: Ignition switch getting hot! I'm not sure about soldering the terminals, just a good crimp tool secures the wires fine. I have tried soldering terminals on one of my projects and had problems with corrosion. It seems the flux in the solder eats away the plating on some terminals allowing corrosion to start. I have seen posts about pros and cons of soldering automotive terminals. Just a thought... Bob __________________ 1970 C20 Long Bed Fleetside - Restoration My truck videos - Youtube

10-12-2021, 01:15 PM	#11
MARKDTN Registered User Join Date: Jan 2011 Location: Chattanooga, TN Posts: 2,129	Re: Ignition switch getting hot! The AAW kits appear to have a new plug so not sure why you would have to replace it? Even so they are probably type 56 connectors. You can buy the terminals and crimp them on if needed-assuming you have enough wire length. That would avoid a splice. Are you exceeding the current capacity of the wiring? If you have a lot of high amp stuff you may need to supply them using relays that (fused) powered direct to battery and are triggered by an ignition source so you can take load off that ignition switch. But I would start with grounds. Proper grounds are so important and so often overlooked. __________________ '83 K20-TPI '73 C10 '79 C10-ex-diesel(SOLD) '07 Tahoe(Son driving) '14 Suburban-DD '71 C10-current project

10-12-2021, 10:42 PM	#12
toolboxchev Registered User Join Date: Jul 2015 Location: 2nd left past the stump on a dirt road. Posts: 2,629	Re: Ignition switch getting hot! Is it when the heater is running? The heater circuit runs through the ignition switch. If you have an AC heater fan which will draw 30 amps or so on high without the AC wiring and relay this could be the culprit. GM did some funny stuff and now nobody supplies a 10 or 15 amp heater only fan. The parts houses just substitute the AC fan for heater only applications. Ask me how I know, I had to completely rebuild my stock wiring harness due to this, plus switches, plugs and all kinds of stuff.

10-18-2021, 09:10 AM	#13
Nick2x2x Registered User Join Date: Mar 2017 Location: Loranger, LA. Posts: 51	Re: Ignition switch getting hot! Sorry Its taken me a while to respond been out of town! So I noticed it while driving after a while. Pulled my key out it was hot as fire but then payed attention a little more. No electronics were on except radio. Later that evening I just ran the truck and the switch was still getting hot. Going to reach out to AAW about the switch I haven't done a whole bunch of trouble shooting on it since it is a fresh build with about 1900 miles. For Cruisin the Coast was the longest and the most i driven it at one time which may be why i noticed it there

10-18-2021, 10:39 AM	#14
Accelo Registered User Join Date: Mar 2015 Location: washington Posts: 2,157	Re: Ignition switch getting hot! American Autowire has so many options and places that supply power to other circuits it is impossible to tell what may be going on for sure. You might start with an amp meter on the supply circuit for the switch. I wouldn't blame American Autowire or there products till some basic testing, by someone that know how to troubleshoot electronic circuits, has been completed.

10-18-2021, 11:50 AM	#15
71CHEVYSHORTBED402 Senior Member Join Date: Feb 2009 Location: Northern Nevada Posts: 7,118	Re: Ignition switch getting hot! Might help....Not "tested" so to speak, I need to install one yet. 1971 with HEI..... If you haven't already, personally I'd swap out the switch for starts. Attached Images __________________ Tony 71 Custom Deluxe, SWB, 2WD, 402, A/C. I developed an assm. guide "kit" for restoring it from ground up. With assys, the guide accts for 1000s of OEM identifications and part numbers, all written in short order. 700+ images include assm, illust., charts, and points of interest. Much of the info. applies to all 67-72 GM trucks, and to a lessor degree all 67-72 GM vehicles. My build thread, and more on the guide https://67-72chevytrucks.com/vboard/...d.php?t=730025 Last edited by 71CHEVYSHORTBED402; 10-18-2021 at 12:03 PM.

10-18-2021, 05:21 PM	#16
BigBird05 Senior Member Join Date: Aug 2019 Location: Cheraw Posts: 1,305	Re: Ignition switch getting hot! I have torn down original GM switches that are 50+ years old and found that with age the grease gets almost solid and the contact surface between the rotating part of the switch and the fixed contacts that the wires connect to can become very burnt making for a lot of resistance. Enough to melt the connector on the back.



Register or Log In To remove these advertisements.

10-19-2021, 03:23 PM	#21
BigBird05 Senior Member Join Date: Aug 2019 Location: Cheraw Posts: 1,305	Re: Ignition switch getting hot! Dose the switch get hot with the ignition on but not running?

10-20-2021, 02:12 PM	#22
StingRay Senior Member Join Date: Mar 2000 Location: Saskatoon,SK,Canada Posts: 2,476	Re: Ignition switch getting hot! I found out the hard way that a replacement heater motor drew far more current than stock. At first I was thrilled that it would blow a pop can off of the dash. Excellent defrost. Eventually that current draw through the ignition switch caused a melt down. __________________ Saskatoon, Saskatchewan Canada

10-21-2021, 07:25 AM	#23
Nick2x2x Registered User Join Date: Mar 2017 Location: Loranger, LA. Posts: 51	Re: Ignition switch getting hot! UPDATE!!!!!!!! Was able to do a little investigation! I used the The ignition Wire (pink) in the AAW wiring harness to feed the Electric fans due to the fans (supposedly) only using 8amps to run! which would have put me at 16 amps total on a a 12ga. wire (rated for 20 amps). Well I have determined that was a LIE! I will be separating the fan feeds and putting 2 inline fuses in and connecting them to the battery link box! Thank you all for the help glad to be a part of this family!

10-21-2021, 07:58 AM	#24
Accelo Registered User Join Date: Mar 2015 Location: washington Posts: 2,157	Re: Ignition switch getting hot! Glad you identified the issue. Typically fans are powered through relays. This removes the load from the control circuits. Cheers.

Register or Log In To remove these advertisements.