Stumped or stupid
Thread Starter
Had a 1976 L-82, 4-sp
Joined: Mar 2011
Posts: 5,338
Likes: 1,213
From: Some days your the dog and some days your the hydrant.
Royal Canadian Navy
Stumped or stupid
My fan switch works fine in all speeds..................but only when one or the other or both doors are are open.
It seems the fan switch control only gets power to operate the blower when the door ajar switch is activated when the door is open. Press in on the switch when the door is open of course and the fan shuts off in any setting of the fan switch. No, I haven't cut or spliced into the fan switch wires or door ajar warning switch. I did remove the AC condensor and piping forward of the VIR over the winter. Now I have this problem. I looked at the wiring diagrams in the 1974 FSM to no avail. I own a 1976. Any ideas on where to start looking for the fault?
It seems the fan switch control only gets power to operate the blower when the door ajar switch is activated when the door is open. Press in on the switch when the door is open of course and the fan shuts off in any setting of the fan switch. No, I haven't cut or spliced into the fan switch wires or door ajar warning switch. I did remove the AC condensor and piping forward of the VIR over the winter. Now I have this problem. I looked at the wiring diagrams in the 1974 FSM to no avail. I own a 1976. Any ideas on where to start looking for the fault?
Thread Starter
Had a 1976 L-82, 4-sp
Joined: Mar 2011
Posts: 5,338
Likes: 1,213
From: Some days your the dog and some days your the hydrant.
Royal Canadian Navy
How would it work if there was no ground? It does work but as I said, the door needs to be open. What has me baffled is that I don't see any electrical relationship between the door ajar button and the fan circuit other than they are both 12V and need a common ground i.e. the chassis. The battery was disconnected all winter and I had the wiring for the starter motor and alternator disconnected and removed the AC condensor, compressor and tubing/hose forward of the VIR. When I reconnected the battery, the fan doesn't operate properly. I'm also having a problem with my amplifier. It cuts power off at very low volume levels rendering it useless for listening. The trouble shooting guide for the amp says its most likely a grounding problem. The amp is directly connected to the negative terminal of the battery. The sound system also worked perfectly until I reconnected the battery after the winter. Could there be a chaffed wire causing all these problems?
Melting Slicks
Joined: Aug 2006
Posts: 3,429
Likes: 20
From: Kingston Ontario
[QUOTE=resdoggie;1581318316]How would it work if there was no ground?
I didn't see a connection between the wipers and the door switch, I opened my door and the wipers worked. Go figure. A ground wire was off somewhere, I didn't fix it, someone else did.
I didn't see a connection between the wipers and the door switch, I opened my door and the wipers worked. Go figure. A ground wire was off somewhere, I didn't fix it, someone else did.
Thread Starter
Had a 1976 L-82, 4-sp
Joined: Mar 2011
Posts: 5,338
Likes: 1,213
From: Some days your the dog and some days your the hydrant.
Royal Canadian Navy
Oh, it didn't click in that your wipers worked with the door open similar to my fan. Wish you had fixed it yourself for the exact answer. It seems more like the door ajar switch is acting as the on/off power for the fan switch vice a grounding problem. Just can't get my head around how that can be. I'm sure the fix will be something easy but as I said, everything works fine, just not the way its supposed to power on and off. Hence, stumped so far.
Team Owner
Joined: Jun 2000
Posts: 38,923
Likes: 1,482
From: Southbound
Cruise-In II Veteran
My advice would be to take another look at what you did over the winter. Based on what you posted, things were fine until that point.
Thread Starter
Had a 1976 L-82, 4-sp
Joined: Mar 2011
Posts: 5,338
Likes: 1,213
From: Some days your the dog and some days your the hydrant.
Royal Canadian Navy
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Thread Starter
Had a 1976 L-82, 4-sp
Joined: Mar 2011
Posts: 5,338
Likes: 1,213
From: Some days your the dog and some days your the hydrant.
Royal Canadian Navy
I was hoping a forum electrical guru could explain how the door ajar switch is acting as an on/off switch for the fan switch. Then, I could take it from there, hopefully. I haven't spliced into any wires related to the fan or the door ajar circuit afaik. I spliced into the dash illumination circuit to connect the aftermarket stereo. I have the console apart and right side dash pad looking for clues but all appears normal.
Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,853
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
The blower motor ground is the same ground the wipers are on... Are the wipers working?
But.. the best way to check this is to run an independent ground to the blower motor housing and see if the motor works.
The grounding circuit being used is the white wire ground on the courtesy lamps. But this same ground can be found at the hood opening alarm switch which is right out there above the blower motor. There is a Jamb type "alarm" switch mounted on a bracket right at the firewall. I suppose it is possible someone needed a ground and thought that this was a good one not knowing it was only ground when the switch was open.
So, I'm wondering if maybe someone didn't splice in on that white ground thinking it was just a normal ground.. it isn't.
Willcox
But.. the best way to check this is to run an independent ground to the blower motor housing and see if the motor works.
The grounding circuit being used is the white wire ground on the courtesy lamps. But this same ground can be found at the hood opening alarm switch which is right out there above the blower motor. There is a Jamb type "alarm" switch mounted on a bracket right at the firewall. I suppose it is possible someone needed a ground and thought that this was a good one not knowing it was only ground when the switch was open.
So, I'm wondering if maybe someone didn't splice in on that white ground thinking it was just a normal ground.. it isn't.
Willcox
Last edited by Willcox Corvette; Jul 15, 2012 at 03:04 PM.
Thread Starter
Had a 1976 L-82, 4-sp
Joined: Mar 2011
Posts: 5,338
Likes: 1,213
From: Some days your the dog and some days your the hydrant.
Royal Canadian Navy
The blower motor ground is the same ground the wipers are on... Are the wipers working?
But.. the best way to check this is to run an independent ground to the blower motor housing and see if the motor works.
The grounding circuit being used is the white wire ground on the courtesy lamps. But this same ground can be found at the hood opening alarm switch which is right out there above the blower motor. There is a Jamb type "alarm" switch mounted on a bracket right at the firewall. I suppose it is possible someone needed a ground and thought that this was a good one not knowing it was only ground when the switch was open.
So, I'm wondering if maybe someone didn't splice in on that white ground thinking it was just a normal ground.. it isn't.
Willcox
But.. the best way to check this is to run an independent ground to the blower motor housing and see if the motor works.
The grounding circuit being used is the white wire ground on the courtesy lamps. But this same ground can be found at the hood opening alarm switch which is right out there above the blower motor. There is a Jamb type "alarm" switch mounted on a bracket right at the firewall. I suppose it is possible someone needed a ground and thought that this was a good one not knowing it was only ground when the switch was open.
So, I'm wondering if maybe someone didn't splice in on that white ground thinking it was just a normal ground.. it isn't.
Willcox
I'll get back at it soon and report back. Thanks to everyone for suggestions thus far.
Le Mans Master
Joined: Jan 2000
Posts: 8,918
Likes: 27
From: New Hill NC
Le Mans Master
Joined: Aug 2006
Posts: 7,426
Likes: 1,559
From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
This BLACK wire that is connected to the starter bolt is the ground for the wiper and blower motor, is this how you connected it?
76 Schematic:
http://www.vetteprojects.com/bmv/mis...tte%201976.pdf
Also the black wire on the temp gauge is the center console ground, check that it connects from the temp gauge to the left side bird cage just above the bottom of the dash.
76 Schematic:
http://www.vetteprojects.com/bmv/mis...tte%201976.pdf
Also the black wire on the temp gauge is the center console ground, check that it connects from the temp gauge to the left side bird cage just above the bottom of the dash.
Burning Brakes
Joined: Jan 2004
Posts: 769
Likes: 0
From: Ft. Lauderdale Fl
I just change my starter and I had 1 black wire about 12ga. and it was connect to the negetive side of the sileniord. I do know there isn't a stock wire connected to that bolt. That wire is a ground for something else, after market.
Le Mans Master
Joined: Jan 2000
Posts: 8,918
Likes: 27
From: New Hill NC
Negative side of the solinoid?
That black ground wire is on every one ever built.
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
Your 78 should have the same wire but connected to one of the bellhousing bolts just behind the starter.
Not sure what you mean by 12 black connected to the "neg side" of the solenoid. Its possible your referring to the fusible link which should be connected to a heavy red wire or 2 depending on what has been done over the years,but it should be connected to the large pos post of the solenoid.Maybe you can confirm what you meant.
Le Mans Master
Joined: Dec 2006
Posts: 8,837
Likes: 1,028
Word of advice from a 57 year old IBEW guy. ANY time you have ghosts, things that should not be that are, suspect a loose/bad ground first. The alternate power paths do strange things.
Lose a ground on a tail light on these cars, and do do happens.
In the power industry, loose nuetrals are ALWAYS suspect. If you turn on a porch light, and your TV goes off, you have lost a nuetral/white wire splice somewhere.
Lose a ground on a tail light on these cars, and do do happens.
In the power industry, loose nuetrals are ALWAYS suspect. If you turn on a porch light, and your TV goes off, you have lost a nuetral/white wire splice somewhere.