Cigarette Lighter and Blower Relay Wiring Questions - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Classics Fan · 01-28-2025, 04:33 PM

I have a 1971 Jimmy that I discovered the cigarette lighter had stopped working. Related to that I believe after investigating and doing some research, recently I noticed a burning smell when the heater blower speed was set on high. It goes away on lower settings. Anyway when I looked at the cigarette connection on the fuse panel I found that connector (orange wire) had some melting. I replaced the connector but the red wire at the back of the lighter still doesn’t have power.

That led me to doing some research and I found the first photo below on a different forum post. It shows both an orange wire and red wire at the CIG fuse panel connection. The second photo is my panel. You can see it has only the orange wire (blue arrow) however, there is also a separate red wire (yellow arrow) I found disconnected that I thought might be the power to the lighter. I connected it to the fuse panel at the post that is directly below the cluster connector (red arrow, it has unswitched power) but still nothing at the lighter.

Anyone have any ideas on what could be going on here? The lighter worked until it didn’t. I hadn’t removed or disconnected any wires at the fuse panel. One thing I found strange is the CIG connection is unfused. Is there a fuse or fusible link somewhere else? I tried to trace the red wire back from the lighter but it disappears behind the dash panel and I didn’t want to pull the panel until I had some answers to my questions.

Thanks in advance for any insight.

**HO455** · 01-28-2025, 10:20 PM

Its my experience that GM typically doesn't fuse the cigarette lighter which can be problematic. I had a lighter short out internally while driving down the freeway in my old S10.

I don't smoke and never used the lighter but out of the blue one day smoke starts billowing out from the dash area where the lighter is. Needless to say I made a sharp right to the side of the road and started tearing wires out of the dash.

I believe that the cigarette lighter and the high speed fan power can share the same connector at the fuse panel. The link explains the circuit as well as has the wiring diagram.

http://67-72chevytrucks.com/vboard/s...d.php?t=705082

Classics Fan · Yesterday, 04:00 PM

So to follow-up and close this post: today I looked closer at the disconnected red wire near the fuse panel and to me it just had to be the lighter wire. I reconnected it to the same blade as yesterday that I thought was constant 12 volts, turned the ignition to Run and was happy to find power to the lighter. I then connected the red wire to the piggyback connector on the orange wire (high blower relay), installed an inline 20 amp fuse to protect them and called it good. I feel much better having this relatively high-amp wire protected. No more melting!

**1970cstblazer** · Yesterday, 06:15 PM

The lighter circuit is protected by the large fusible link in the main harness by the battery.

**HO455** · Yesterday, 06:27 PM

No melting is good! Best to keep the smoke inside the wires so everything works.

Classics Fan · Yesterday, 07:57 PM

Quote:

Originally Posted by 1970cstblazer

The lighter circuit is protected by the large fusible link in the main harness by the battery.

If that’s the case wouldn’t the blower relay circuit also be protected since they get power from the same blade on the fuse panel? If so why did I experience melting on the relay fuse panel connector?

**HO455** · Today, 11:22 AM

The nature of fuseable links is that they are a slow blow type of fuse. Meaning that if it is rated for 30 amps once exposed to 35 amps it may take as long as a minute to blow where a fuse would blow in a matter of seconds.

In your case both the fuseable link and the wiring at the fuse block were heating up simultaneously. You were only able to smell the wires in the cab.

I would recommend doing a physical inspection of the fuseable link by bending or flexing the fuseable link looking for stiff or ridged areas. When a fuseable link fails it shouldn't show any signs of overheating. So flexing and stretching the link should allow you to detect any melting of the conductors inside.

Another possibility is that someone in the past replaced the factory fuseable link with an incorrect wire that doesn't protect the harness.

I posted some information on fuseable links in post 469 in the link

http://67-72chevytrucks.com/vboard/s...or#post8564169

01-28-2025, 04:33 PM	#1
Classics Fan Registered User Join Date: Jan 2018 Location: Anacortes. WA Posts: 136	Cigarette Lighter and Blower Relay Wiring Questions I have a 1971 Jimmy that I discovered the cigarette lighter had stopped working. Related to that I believe after investigating and doing some research, recently I noticed a burning smell when the heater blower speed was set on high. It goes away on lower settings. Anyway when I looked at the cigarette connection on the fuse panel I found that connector (orange wire) had some melting. I replaced the connector but the red wire at the back of the lighter still doesn’t have power. That led me to doing some research and I found the first photo below on a different forum post. It shows both an orange wire and red wire at the CIG fuse panel connection. The second photo is my panel. You can see it has only the orange wire (blue arrow) however, there is also a separate red wire (yellow arrow) I found disconnected that I thought might be the power to the lighter. I connected it to the fuse panel at the post that is directly below the cluster connector (red arrow, it has unswitched power) but still nothing at the lighter. Anyone have any ideas on what could be going on here? The lighter worked until it didn’t. I hadn’t removed or disconnected any wires at the fuse panel. One thing I found strange is the CIG connection is unfused. Is there a fuse or fusible link somewhere else? I tried to trace the red wire back from the lighter but it disappears behind the dash panel and I didn’t want to pull the panel until I had some answers to my questions. Thanks in advance for any insight. Attached Images

01-28-2025, 10:20 PM	#2
HO455 Post Whore Join Date: Feb 2016 Location: Portland Oregon Posts: 11,501	Re: Cigarette Lighter and Blower Relay Wiring Questions Its my experience that GM typically doesn't fuse the cigarette lighter which can be problematic. I had a lighter short out internally while driving down the freeway in my old S10. I don't smoke and never used the lighter but out of the blue one day smoke starts billowing out from the dash area where the lighter is. Needless to say I made a sharp right to the side of the road and started tearing wires out of the dash. I believe that the cigarette lighter and the high speed fan power can share the same connector at the fuse panel. The link explains the circuit as well as has the wiring diagram. http://67-72chevytrucks.com/vboard/s...d.php?t=705082 __________________ 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

Yesterday, 04:00 PM	#3
Classics Fan Registered User Join Date: Jan 2018 Location: Anacortes. WA Posts: 136	Re: Cigarette Lighter and Blower Relay Wiring Questions So to follow-up and close this post: today I looked closer at the disconnected red wire near the fuse panel and to me it just had to be the lighter wire. I reconnected it to the same blade as yesterday that I thought was constant 12 volts, turned the ignition to Run and was happy to find power to the lighter. I then connected the red wire to the piggyback connector on the orange wire (high blower relay), installed an inline 20 amp fuse to protect them and called it good. I feel much better having this relatively high-amp wire protected. No more melting!

Yesterday, 06:15 PM	#4
1970cstblazer All stock and staying that way Join Date: Jul 2003 Location: Elkland, PA Posts: 1,950	Re: Cigarette Lighter and Blower Relay Wiring Questions The lighter circuit is protected by the large fusible link in the main harness by the battery. __________________ 1970 K/5 Blazer CST 4WD, TOTM winner December 2024! Medium Bronze, 93k ACT. miles, 350, 4 speed, rear positraction, 16.5" x 8.25" HD Kelsey Hayes wheel option, tilt, tach, vacuum, AM/FM, manual throttle...Dad ordered and purchased new 4/70. Currently frame off restoration finally getting close to completion.. 1972 Cheyenne Super 20 2WD, DK Blue/White, 90K ACT. miles, 402, TH400, 4.10 open, tilt, tach, vacuum, A/C, AM/FM, manual throttle.. A mostly original paint never rusted Texas survivor... 2017 Sierra 1500 SLT 4WD, Black, 45k miles, 5.3, 6L80E, 3.42 LS, 20" polished wheels, everything but moonroof and 6.2... 2019 Canyon SLT 4WD, White, 62k miles, 3.6, 8L45, 3.23 LS, 18" wheels

Yesterday, 06:27 PM	#5
HO455 Post Whore Join Date: Feb 2016 Location: Portland Oregon Posts: 11,501	Re: Cigarette Lighter and Blower Relay Wiring Questions No melting is good! Best to keep the smoke inside the wires so everything works. __________________ 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

Today, 11:22 AM	#7
HO455 Post Whore Join Date: Feb 2016 Location: Portland Oregon Posts: 11,501	Re: Cigarette Lighter and Blower Relay Wiring Questions The nature of fuseable links is that they are a slow blow type of fuse. Meaning that if it is rated for 30 amps once exposed to 35 amps it may take as long as a minute to blow where a fuse would blow in a matter of seconds. In your case both the fuseable link and the wiring at the fuse block were heating up simultaneously. You were only able to smell the wires in the cab. I would recommend doing a physical inspection of the fuseable link by bending or flexing the fuseable link looking for stiff or ridged areas. When a fuseable link fails it shouldn't show any signs of overheating. So flexing and stretching the link should allow you to detect any melting of the conductors inside. Another possibility is that someone in the past replaced the factory fuseable link with an incorrect wire that doesn't protect the harness. I posted some information on fuseable links in post 469 in the link http://67-72chevytrucks.com/vboard/s...or#post8564169 __________________ 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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