Need help on an electrical problem 71 Vette
Thread Starter
Instructor
Joined: Mar 2020
Posts: 118
Likes: 15
From: Texas
Need help on an electrical problem 71 Vette
Hope everyone is doing well and enjoying their rides. I have a 1971 with a 350 and a Tremec TKX 5 speed. I have replaced one of the engine wiring harnesses and the rear wiring harness. I am still running a coil witht he original distributor and added a pertronix. Other than that most of the wiring is original. I have a developed a problem a fuse shorting.
When I put the key in and turn it - first click /acc - no problem, second click /ign - the fuse for the turn signals and the back up lights blows. I thought it might be the turn signal relay because historically the horn would intermittently go off and then - last week - subsequently my turn signals stopped working leaving only my hazard lights operational- so I replaced the turn signal harness in the column. Problem not fixed. So I started checking rear light bulbs (LED) and problem persists after I removed them all. So I thought its the back up light harness - maybe it melted. Checked it and from the underside of the transmission tunnel to the TKX connection - wiring is fine. So...I thought maybe I compromised one of the wires in the new harness...so I disconnected it and tried again.
Now - still in the same spot. When I turn the key and and hit the ignition point - the 20A fuse for the turn signals / back up lights immediately pops. Has anyone elese had this problem? Any help would be appreciated.
When I put the key in and turn it - first click /acc - no problem, second click /ign - the fuse for the turn signals and the back up lights blows. I thought it might be the turn signal relay because historically the horn would intermittently go off and then - last week - subsequently my turn signals stopped working leaving only my hazard lights operational- so I replaced the turn signal harness in the column. Problem not fixed. So I started checking rear light bulbs (LED) and problem persists after I removed them all. So I thought its the back up light harness - maybe it melted. Checked it and from the underside of the transmission tunnel to the TKX connection - wiring is fine. So...I thought maybe I compromised one of the wires in the new harness...so I disconnected it and tried again.
Now - still in the same spot. When I turn the key and and hit the ignition point - the 20A fuse for the turn signals / back up lights immediately pops. Has anyone elese had this problem? Any help would be appreciated.
Old Fart Pilot
Joined: Apr 2010
Posts: 1,891
Likes: 961
From: Spokane, WA
Are you sure about your switch positions? Isn't the ACC position one click CCW from OFF/LOCK? The 1st CW position from OFF is RUN and the 2nd is START.
From your description, I'd GUESS (I'm no expert) that your problem might have something to do with the starting system or the higher voltage to the coil during start and some sort of short to that blinker circuit.
DISREGARD ALL THE ABOVE! Damn Google AI screwed up again. It said that CCW once was ACC for a 71 vette, but when I went to the basement to check the switch on my column that's been out of the car for years, I found that there is no CCW position from OFF/LOCK. All positions are CW from OFF.
When you say the fuse blows in the IGN position, do you mean the RUN position rather than the START position?
From what I can decipher from the wiring diagrams, there shouldn't be any extraneous loads on that 20A circuit except for the b/u lamps and the blinkers (including the indicator lamps in the gauge clusters).
Has anything been done to the car just before the problem developed? How long have the LED bulbs in the rear been installed and are there LEDs front and rear?
Sounds like a short to ground somewhere in that blinker & b/u circuit. Could be in the fuse panel itself, one of the harness connections or the connectors on the steering column. Could even be a short in the blinker switch assembly or a bad turn signal flasher. I HATE trying to track down hidden shorts....
From your description, I'd GUESS (I'm no expert) that your problem might have something to do with the starting system or the higher voltage to the coil during start and some sort of short to that blinker circuit.
DISREGARD ALL THE ABOVE! Damn Google AI screwed up again. It said that CCW once was ACC for a 71 vette, but when I went to the basement to check the switch on my column that's been out of the car for years, I found that there is no CCW position from OFF/LOCK. All positions are CW from OFF.
When you say the fuse blows in the IGN position, do you mean the RUN position rather than the START position?
From what I can decipher from the wiring diagrams, there shouldn't be any extraneous loads on that 20A circuit except for the b/u lamps and the blinkers (including the indicator lamps in the gauge clusters).
Has anything been done to the car just before the problem developed? How long have the LED bulbs in the rear been installed and are there LEDs front and rear?
Sounds like a short to ground somewhere in that blinker & b/u circuit. Could be in the fuse panel itself, one of the harness connections or the connectors on the steering column. Could even be a short in the blinker switch assembly or a bad turn signal flasher. I HATE trying to track down hidden shorts....
Last edited by nwav8tor; Yesterday at 03:24 AM.
Burning Brakes
Joined: Apr 2020
Posts: 788
Likes: 418
From: Western NY
this may have nothing to do with your issue but FWIW: 2 or 3 years ago I had a problem with the fuse blowing for the brake lights and turn signals - but the emrg flashers still worked. long story short I used too long of a screw when re installing the triangular panel that bolts under the steering column. the screw that screws up into the middle of the steering column was too long and screwed thru the wiring harness that runs the length of the column and shorted one of the wires to ground. you mentioned you replaced steering column harness so just make sure you didn't do what I did.
Pat
Pat
Advanced
Joined: Apr 2014
Posts: 65
Likes: 12
From: White Lake, Mich
I agree with PSPICCI response. I just went thru this exact problem on my 70 after I removed the left side I/P . I installed the wrong screw (too long) and it create problem with the turn signals and blowing the fuse.
JFG15
JFG15
Thread Starter
Instructor
Joined: Mar 2020
Posts: 118
Likes: 15
From: Texas
Hope everyone is doing well and enjoying their rides. I have a 1971 with a 350 and a Tremec TKX 5 speed. I have replaced one of the engine wiring harnesses and the rear wiring harness. I am still running a coil witht he original distributor and added a pertronix. Other than that most of the wiring is original. I have a developed a problem a fuse shorting.
When I put the key in and turn it - first click /acc - no problem, second click /ign - the fuse for the turn signals and the back up lights blows. I thought it might be the turn signal relay because historically the horn would intermittently go off and then - last week - subsequently my turn signals stopped working leaving only my hazard lights operational- so I replaced the turn signal harness in the column. Problem not fixed. So I started checking rear light bulbs (LED) and problem persists after I removed them all. So I thought its the back up light harness - maybe it melted. Checked it and from the underside of the transmission tunnel to the TKX connection - wiring is fine. So...I thought maybe I compromised one of the wires in the new harness...so I disconnected it and tried again.
Now - still in the same spot. When I turn the key and and hit the ignition point - the 20A fuse for the turn signals / back up lights immediately pops. Has anyone elese had this problem? Any help would be appreciated.
When I put the key in and turn it - first click /acc - no problem, second click /ign - the fuse for the turn signals and the back up lights blows. I thought it might be the turn signal relay because historically the horn would intermittently go off and then - last week - subsequently my turn signals stopped working leaving only my hazard lights operational- so I replaced the turn signal harness in the column. Problem not fixed. So I started checking rear light bulbs (LED) and problem persists after I removed them all. So I thought its the back up light harness - maybe it melted. Checked it and from the underside of the transmission tunnel to the TKX connection - wiring is fine. So...I thought maybe I compromised one of the wires in the new harness...so I disconnected it and tried again.
Now - still in the same spot. When I turn the key and and hit the ignition point - the 20A fuse for the turn signals / back up lights immediately pops. Has anyone elese had this problem? Any help would be appreciated.
Thread Starter
Instructor
Joined: Mar 2020
Posts: 118
Likes: 15
From: Texas
I have not yet reinstalled the cover unde the column - but will be careful not to do that I isolated it to the to the coil. If I disconnect the coil first from the fuse block - and I put the key in the start position - the blinkers work fine and the fuse does not blow. If I think reconnect the coil to the fuse block and turn the key to start then the fuse for the blinkers and the back up lights blows. I have no idea what would cause that.
Thread Starter
Instructor
Joined: Mar 2020
Posts: 118
Likes: 15
From: Texas
this may have nothing to do with your issue but FWIW: 2 or 3 years ago I had a problem with the fuse blowing for the brake lights and turn signals - but the emrg flashers still worked. long story short I used too long of a screw when re installing the triangular panel that bolts under the steering column. the screw that screws up into the middle of the steering column was too long and screwed thru the wiring harness that runs the length of the column and shorted one of the wires to ground. you mentioned you replaced steering column harness so just make sure you didn't do what I did.
Pat
Pat
Thread Starter
Instructor
Joined: Mar 2020
Posts: 118
Likes: 15
From: Texas
Are you sure about your switch positions? Isn't the ACC position one click CCW from OFF/LOCK? The 1st CW position from OFF is RUN and the 2nd is START.
From your description, I'd GUESS (I'm no expert) that your problem might have something to do with the starting system or the higher voltage to the coil during start and some sort of short to that blinker circuit.
DISREGARD ALL THE ABOVE! Damn Google AI screwed up again. It said that CCW once was ACC for a 71 vette, but when I went to the basement to check the switch on my column that's been out of the car for years, I found that there is no CCW position from OFF/LOCK. All positions are CW from OFF.
When you say the fuse blows in the IGN position, do you mean the RUN position rather than the START position?
From what I can decipher from the wiring diagrams, there shouldn't be any extraneous loads on that 20A circuit except for the b/u lamps and the blinkers (including the indicator lamps in the gauge clusters).
Has anything been done to the car just before the problem developed? How long have the LED bulbs in the rear been installed and are there LEDs front and rear?
Sounds like a short to ground somewhere in that blinker & b/u circuit. Could be in the fuse panel itself, one of the harness connections or the connectors on the steering column. Could even be a short in the blinker switch assembly or a bad turn signal flasher. I HATE trying to track down hidden shorts....
From your description, I'd GUESS (I'm no expert) that your problem might have something to do with the starting system or the higher voltage to the coil during start and some sort of short to that blinker circuit.
DISREGARD ALL THE ABOVE! Damn Google AI screwed up again. It said that CCW once was ACC for a 71 vette, but when I went to the basement to check the switch on my column that's been out of the car for years, I found that there is no CCW position from OFF/LOCK. All positions are CW from OFF.
When you say the fuse blows in the IGN position, do you mean the RUN position rather than the START position?
From what I can decipher from the wiring diagrams, there shouldn't be any extraneous loads on that 20A circuit except for the b/u lamps and the blinkers (including the indicator lamps in the gauge clusters).
Has anything been done to the car just before the problem developed? How long have the LED bulbs in the rear been installed and are there LEDs front and rear?
Sounds like a short to ground somewhere in that blinker & b/u circuit. Could be in the fuse panel itself, one of the harness connections or the connectors on the steering column. Could even be a short in the blinker switch assembly or a bad turn signal flasher. I HATE trying to track down hidden shorts....
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Thread Starter
Instructor
Joined: Mar 2020
Posts: 118
Likes: 15
From: Texas
Thread Starter
Instructor
Joined: Mar 2020
Posts: 118
Likes: 15
From: Texas
Race Director
Joined: Oct 2008
Posts: 19,172
Likes: 1,668
From: Long Island
disconnect the wires from the coil at the coil and see if the fuse blows. If it does the red wire is shorted.
If it does not I would replace the coil and check for grounded wires by the coil.
If it does not I would replace the coil and check for grounded wires by the coil.
Last edited by BLUE1972; Today at 08:35 AM.
Pro
Joined: Nov 2023
Posts: 695
Likes: 334
From: Aubrey TX
The only answer I have is that - when I bought in 2020 thats where it was wired into. Even after I rebuilt the motor - I just put it back in the same place. Its actuall coming from a four way relay/fuse that sits between my coil and the the fuse box. I have a pentronix on the distributor and was told I need the relay to manage it.