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-   -   Electrical Issues (http://www.clubcobra.com/forums/era-speak-bob-putnam/118602-electrical-issues.html)

Cobradad 01-04-2013 10:56 AM
Electrical Issues
 
Hi all, hope everyone had a great Holiday Season. Back with my usual issues, electrics. I keep blowing the #4 fuse whenever I use my turnsignals. It does not blow right away, but eventually the fuse will blow. Since the circuit shares the fan relay, I tried to isolate the problem. I resorted to hand signals for my turns. ( have not done that since my 1966 Ducati). No more blown fuses. I'm hopeless with electrics, so anyone have any suggestions on how to hunt this down or anyone else experience this problem? I have one of the older cars, chasis 188. Thanks.

mrmustang 01-04-2013 11:15 AM
Quote:
Originally Posted by Cobradad (Post 1225754)
Hi all, hope everyone had a great Holiday Season. Back with my usual issues, electrics. I keep blowing the #4 fuse whenever I use my turnsignals. It does not blow right away, but eventually the fuse will blow. Since the circuit shares the fan relay, I tried to isolate the problem. I resorted to hand signals for my turns. ( have not done that since my 1966 Ducati). No more blown fuses. I'm hopeless with electrics, so anyone have any suggestions on how to hunt this down or anyone else experience this problem? I have one of the older cars, chasis 188. Thanks.
Did you ever change out to the new aluminum radiator updated fan assembly that came with the car? if not, the fan relay itself could be the culprit, not sure of the part number (I am sure that Bob will chime in with it), but it may need to be replaced. Had a similar issue with ERA234 when I owned it, replaced the relay and the fan switch, never had an issue after that.


Bill S.

Tommy 01-04-2013 01:21 PM
Cobradad,
If the fuse blows within a hour or so, try this to narrow down the problem. On a nice cool day when you're not likely to even need a fan, disconnect the fan relay and drive the car. If the fuse blows again, it must be the only other device on the circuit. If the fuse doesn't blow in the usual time, reconnect the fan relay and see if it blows. ... One more thing to consider. It's possible that one of the two devices is drawing more current than it should, but not enough to blow the fuse until the other device activates at the same time. For example, the fan relay could be drawing too much current, but not enough to blow the fuse until the added load of the turn signal kicks in. That would make it look like the turn signal is the problem when it isn't.

patrickt 01-04-2013 04:53 PM
Quote:
Originally Posted by Cobradad (Post 1225754)
... so anyone have any suggestions on how to hunt this down or anyone else experience this problem? I have one of the older cars, chasis 188. Thanks.
You either have a "jiggly short," a component is failing, or you're right on the line, amperage wise, of the fuse. You can either screw around guessing, or you can buy an inductive ammeter, like mine, and just clamp it around the circuit right at the fuse, around the feed to the fan, the feed to your signals, etc. and see not only what they are drawing cold, but what they draw when they're hot. Your electric fan does not always draw the same amperage -- there can be quite a difference as the temperature rises.

http://www.clubcobra.com/photopost/d.../charge002.jpg

Dangerous Doug 01-04-2013 05:09 PM
Cobradad indicates that he's isolated the problem to the turn signals.

Can you further isolate by disconnecting left and right, then front and rear?

Painful, I know.

DD

patrickt 01-04-2013 05:13 PM
Quote:
Originally Posted by Dangerous Doug (Post 1225807)
Cobradad indicates that he's isolated the problem to the turn signals.

Can you further isolate by disconnecting left and right, then front and rear?

Painful, I know.

DD
But if the fan is not running do the turn signals still blow the fuse?

mrmustang 01-04-2013 05:21 PM
As a follow up, we started this thread back in 2011 on the same subject

http://www.clubcobra.com/forums/era-...gremloins.html

patrickt 01-04-2013 05:34 PM
I can think of a half dozen ways it could be failing. But if Cobradad doesn't want to take current readings then splitting the circuit so the fan has its own dedicated fused feed is the next easiest thing. It'll either fix the problem entirely, or cut the problem in half, depending.:cool:

ERA 778 01-04-2013 06:00 PM
When I first got my running I too was blowing fuses, but a different one (#6). I was losing the taillights. Finally tracked it down to the taillight sockets themselves. The wire contact had pushed itself through the socket and was making contact with the taillight frame when I hit a bump, shorting out the circuit. You might have the same thing going on, but with the turn signal/brake element. Fixing it was easy. I just slid the contact back and packed a piece of foam rubber between it and the frame part.

patrickt 01-04-2013 06:04 PM
Quote:
Originally Posted by ERA 778 (Post 1225820)
... when I hit a bump, shorting out the circuit. You might have the same thing going on, but with the turn signal/brake element.
Yes, we call that a "jiggly short." And you diagnose it by jiggling different wires until you short the circuit out.

Cobradad 01-05-2013 05:50 PM
Thanks for the ideas. Bill I did install the new radiator back in the spring. I then put a new fan relay in and added a circuitbreaker to the fan circuit. I've thought that perhaps the use of the turnsignals while the fan is running might be the contributing factor. This has existed prior to installing the new radiator. I can use the turnsignals while the fan is running and they do not blow immediately, so it appers to be more intermittant. Thanks to living in the cold of PA, I'll add this to the winter list of putting heat in the car and new carpet. Thanks again for the guidance.

patrickt 01-05-2013 05:54 PM
Quote:
Originally Posted by Cobradad (Post 1225953)
I then put a new fan relay in and added a circuitbreaker to the fan circuit.
Wait a minute... your fan now has a circuit breaker and a fuse, on the same circuit?

Cobradad 01-05-2013 06:19 PM
No, circuit breaker is on the circuit that the fan itself runs off of, #1 I believe. if i remember correctly, the #4 circuit controls the turnsignals, voltage regulator and the fan relay.

patrickt 01-05-2013 06:27 PM
Quote:
Originally Posted by Cobradad (Post 1225963)
No, circuit breaker is on the circuit that the fan itself runs off of, #1 I believe. if i remember correctly, the #4 circuit controls the turnsignals, voltage regulator and the fan relay.
I see. Both the signal lights and the relay take little current, so it's almost a certainty that it's a "jiggle short" or possibly the trailer relay that lets the brake lights and turn signals work in harmony.


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