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Canadian Poncho Homepage -> Canadian Poncho -> 65-70 Full Size Interior Tech Forum -> Electrical gremlins. Help!!!!!
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67rag396


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Electrical gremlins. Help!!!!!
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I am trying to get the 67 2+2 ready to go to the final S & S of the year. It now runs but over the past week it keeps blowing the 10 amp fuse on the guage/back-up light circuit. This has been an intermittent problem.

I have used the accessory spade from this circuit to power the Tach, Oil Pressure Guage and Water Temp Guage.
I have just discovered that at some point while the engine is running the fuse blows. When it is cold it does not blow. When warm it will blow the fuse when only the Temp Guage is attached. When I say warm I mean just barely warm not full operating temp.
Without the temp guage everything else is OK on the circuit.
Has anyone experienced this?
Any ideas as to the repair?
I know I can run without the temp guage or buy and try a new sending unit, or replace all the wiring or!!!!!
Help!!!!

Rick

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1967 Parisienne 2+2
1967 Grande Parisienne

1967 Laurentian
1967 Strato Chief


Remember, "The Government" only has money confiscated from us.

 

 
73SC


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I almost hate to ask. Is that circuit correctly closed with a 10 amp or should it be a higher rated fuse?

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Ray White, Toronto ON

Formerly - The one and only 1973 LeMans 454 "Astro-Jet"

Built March 9, 1973 - Oshawa ON

1993 Corvette Convertible LT 1

Built January 10, 1993 - Bowling Green Kentucky 

 
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2drpost


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you're powering alot with a 10A fuse, try a 20A.

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67rag396


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The 10 amp fuse is correct. I just got off the Autometer site and they recommend a separate 1 amp fuse that I don't have. The car only has idiot lights and a fuel guage on the circuit and they appear to be OK when the fuse has not blown.
This is all occurring in the shop without actually driving the car anywhere. I have only been running it to try an eliminate exhaust leaks and now electrical.
When I used my last 10 amp fuse, I tried a 30 amp and it immediately blew.

Rick

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1967 Parisienne 2+2
1967 Grande Parisienne

1967 Laurentian
1967 Strato Chief


Remember, "The Government" only has money confiscated from us.

 

 
73SC


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67rag396 wrote:

When I used my last 10 amp fuse, I tried a 30 amp and it immediately blew.

Rick


Then doesn't that mean it is shorting? You'll have to trace the wires or pull new I think.



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Ray White, Toronto ON

Formerly - The one and only 1973 LeMans 454 "Astro-Jet"

Built March 9, 1973 - Oshawa ON

1993 Corvette Convertible LT 1

Built January 10, 1993 - Bowling Green Kentucky 

 
455gto


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On both of my cars it has been a wire that was touching metal. Start at the back up lights and go forward.

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4SPEED427


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You could try unplugging the harness connector under the drivers left foot area where it sends the backup light power to the back. That would narrow down if it's in the back part or up front somewhere.

By chance does it blow only when you are putting it into reverse in the shop? (Dumb question, I know, but gotta ask the obvious)

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1966 Strato Chief 2 door, 427 4 speed, 45,000 original miles 

1966 Grande Parisienne, 396 1 of 23 factory air cars (now converted to a "factory" 4 speed)
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67rag396


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Backup harness not connected at all.
No problem when engine is cold.
Only a problem after several minutes of engine running and starting to warm up.
If it was a wiring short I would expect it to always blow.
Does it make any sense that it would be a sender problem which is only triggered above some specific temperature?
I am now thinking that I find a new sender tomorrow.
Then replace the sender and test.
If that does not solve the problem I will tear out the wiring, buld a new harness and re-try.


Thanks for letting me think with some helpfull hints.

I hate intermittent electrical issues, they always take way too long to solve.

Rick

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1967 Parisienne 2+2
1967 Grande Parisienne

1967 Laurentian
1967 Strato Chief


Remember, "The Government" only has money confiscated from us.

 

 
4SPEED427


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Is this a factory temp gauge?

If so, if you take off the wire at the sender and ground it, that does the same thing as making the gauge show max heat if I am correct. Will it blow the fuse instantly if you do that?


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1966 Strato Chief 2 door, 427 4 speed, 45,000 original miles 

1966 Grande Parisienne, 396 1 of 23 factory air cars (now converted to a "factory" 4 speed)
67rag396


Poncho Master!

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Carl,
This is an aftermarket Autometer Guage. The car only had idiot lights originally.

Rick

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1967 Parisienne 2+2
1967 Grande Parisienne

1967 Laurentian
1967 Strato Chief


Remember, "The Government" only has money confiscated from us.

 

 
4SPEED427


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Sorry, I don't know the wiring on that one. I looked at their website, and it sounds pretty basic to wire it in.

What you say sure makes sense that as soon as the sender starts to allow current it blows the fuse. I am assuming that the gauge is powered and the sender provides the ground.

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1966 Strato Chief 2 door, 427 4 speed, 45,000 original miles 

1966 Grande Parisienne, 396 1 of 23 factory air cars (now converted to a "factory" 4 speed)
67rag396


Poncho Master!

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I think before work tomorrow I will try disconnecting at the sender end and test touching the block before warming the engine and see what that does.
I have never heard anyone complain about a sender before so I am thinking it is my wiring that is the problem. The flip side is that it only seems to happen when the guage should be starting to move.
New wiring harness is lots of time, sending unit not as much time or aggravation but more money. Time and money will solve most of these things.

Rick

__________________

1967 Parisienne 2+2
1967 Grande Parisienne

1967 Laurentian
1967 Strato Chief


Remember, "The Government" only has money confiscated from us.

 

 
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4SPEED427


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If that blows the fuse, what if you would unhook the sender wire at the gauge and temporarily run a jumper wire from the sender to gauge and try again? That would eliminate that wire. The other side shouldn't be the problem (power wire) because if it was shorted, it should blow the fuse all the time, right?

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1966 Strato Chief 2 door, 427 4 speed, 45,000 original miles 

1966 Grande Parisienne, 396 1 of 23 factory air cars (now converted to a "factory" 4 speed)
67rag396


Poncho Master!

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The wiring checked out OK so I replaced the sender on one end and the guage on the other. Everything seems to work again.
In order to remove the sender fron the engine without making a mess it necessary to drain the block. I didn't.

Thanks for the helpfull hints.

Rick

__________________

1967 Parisienne 2+2
1967 Grande Parisienne

1967 Laurentian
1967 Strato Chief


Remember, "The Government" only has money confiscated from us.

 

 
73SC


A Poncho Legend!

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Recently change my temp sender too. I let 65 Camino do it, he was real fast barely spilled a drop! teamwork.gif

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Ray White, Toronto ON

Formerly - The one and only 1973 LeMans 454 "Astro-Jet"

Built March 9, 1973 - Oshawa ON

1993 Corvette Convertible LT 1

Built January 10, 1993 - Bowling Green Kentucky 

 
67rag396


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Also FYI the new sender has metric nuts argh!!!!!!. I have now stumbled on a few aftermarket items that come with metric nuts.

Rick

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1967 Parisienne 2+2
1967 Grande Parisienne

1967 Laurentian
1967 Strato Chief


Remember, "The Government" only has money confiscated from us.

 

 
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