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Re: 68 BB Fusible Link
Still have not got anywhere with this. the 14 ga FL at the starter shows no signs of any damage or of having been cooked. Still no electrical power other than ignition key buzzer when key in and door open. I REALLY NEED SOME HELP AT THIS POINT!
Thanks in advance,
Noel -
Re: 68 BB Fusible Link
The main FL (at starter motor) can go 'south' without dramatic evidence... In these cases, two things will be evident:
(1) When you unwrap the harness tape at the starter to get to the FL, it'll feel somewhat soft and 'spongy' between your fingers.
(2) NOTHING that's electrical in the cabin will be functional.
I suspect that since you have some things working in the cockpit, you probably don't have a main FL failure... But, you can check by 'probing' it with an ohmeter.
DISCONNECT the battery, pierce the unexposed side of FL with a pin and measure the resistance across the FL.Comment
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Re: 68 BB Fusible Link
Thanks Jack. Its a new harness and the FL is fully exposed up to the hard, rubber cylindrical sleave that protects the linked ends; I am pretty confident that it is intact and even more so now given your comment on having some juice in the intertior (ie ignition buzzer).Comment
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Re: 68 BB Fusible Link
Nothing is for ceertain these days, but replacement fusible links used to be available via the dealership parts counter (From the "Standard Parts Catalog")Bill Clupper #618Comment
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Re: 68 BB Fusible Link
I believe they still are available from GM/Chevy... But, the last time I needed one (my 71's main FL went bye bye when we stopped for lunch in Dinosaur's Breath, Wyoming enroute to the Monterey National convention on the National Road Tour) I had a choice.
Wait for the part to arrive via GMSO from Lansing, Michigan for $12 and some change or let the local Chevy dealer walk across the street to the FLAPS and grab one off-the-shelf for $3.49.
Now, that was a restoration/preservation command decision I really had to SWEAT! I think it too me all of 18-20 seconds to render a decision...
BTW, the Chevy folks in 'Dino' were really friendly and helpful, but a little on the 'slow' side... I had to ask premission to watch the mechanic work on my car, show him where the battery was 'hidden' and then explain to several techs that Corvette was different from Chevy passenger car in terms of where the FL 'lived'.
Later, when I got the 'bad news' from the parts department on the availability of a replacement FL, I had to suggest to the parts mgr that perhaps he might want to check with the 'competition' directly across the street! But, they got me up and running and everybody was a happy camper when she roared to life once more...Comment
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Re: 68 BB Fusible Link
That's an EXCELLENT point, Terry! In '68 the horn relay was a one-year only Delco Remy 1115862 which, like later years, had the key minder buzzer inside. It derived power from the horn relays' side terminal's B+ bus and the only cockpit portion of the circuit was ground back through the engine harness through the firewall and to the ignition and door switches.
So, before discarding the notion the car's main FL popped, take my alternate advice (trust by verify) by checking the existing FL for continuity...Comment
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Re: 68 BB Fusible Link
Jack, I was thinking the ground through the ignition switch and door switch was probably the same -- thus my question.
Noel,
In 40+ years of working with electricity I Have learned NEVER to assUme anything. Of course, the cost of making assumptions in my job can be someones life. In the case of Corvettes one hopes the worst case is the car and maybe garage burn down.
BTW: Try your best to find the short BEFORE you replace the fusible link. Those things don't go bad for no reason. It takes quite a bit of current to make them open up. They are hardly precision devices. They ARE a safety device to keep your car from burning to the wheels, so find the fault first.TerryComment
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Re: 68 BB Fusible Link
Note that I still have not repaired and reconnected the original areas where the FL's cooked (behind ignition shielding and horn relay). This includes the connection to the horn relay - right angle spade clip - that has both the FL and the black wire soldered to it. Might be a stupid question, but without those circuits completed, will there be no juice at all?Comment
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Re: 68 BB Fusible Link
I believe what you have not connected is indeed the main power source to the system. The electrical diagram in either the service manual or the AIM would make this clear.Bill Clupper #618Comment
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Re: 68 BB Fusible Link
The question is akin to 'horseshoes and hand grenades'... How fully open circuit did each of the FL's go when they let loose...completely, 99.2% open circuit, 86.9% open circuit?
Like Terry said, don't take changes. Find and fix the source(s) of the short circuiting, repair or replace the wiring affected. THEN, execute the replacement of your FL's before re-connecting the battery...Comment
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Re: 68 BB Fusible Link
Thanks for all information, I guess I have some work to do here to make sure I don't have a much bigger issue and I am going to have to get a good wiring diagram - the one in the MBI 66-82 shop manual does strike be as being detailed enough and more importantly electrical is not one of my strengths
- As I mentioned in original post, it looks like the original culprit was orange FL that goes between the two larger red wires and the black wire - behind the the ignition shielding - rubbed against the shield and shorted against it. The orange FL between the the black wire and horn relay was also burnt.
- Where do the the two red wires and the black wire behind the shielding ultimately go or what are they providing power to (black to the the ammeter?)? By allowing the the two red wires to short against the ignition shielding, which like an idiot I did, what else could have cooked
- From the horn relay, the spade clip has the black FL that goes to a red wire and the orange FL that goes to the black / white striped wire. What is on these circuits or what are they providing power to?
Thanks again for all the help,
NoelComment
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Re: 68 BB Fusible Link
Noel,
It sounds like you have identified the point of the short. The only damage that will cause is between the short and the battery positive, or the red wire on the horn relay. A good wiring diagram will point you to where to look, and so will some here who are more familiar with your year Corvette than I am.
From other's posts here, the best wiring diagram seems to be from Dr. Rebuild. Those folks say it is colored (makes tracing the circuit a whole lot easier) and laminated so you can mark on it in grease pencil. There are some errors in the Chevrolet Service Manual wiring diagrams, and posters here claim the Doctor has corrected those. I have no personal experience with his diagrams, but I would rely on the recommendations of other posters here.
To start, with the battery disconnected, I would use the ohms scale on the VOM (or continuity scale if your meter has such a position) to check the FL at the horn relay (mentioned in your third bullet above) and the two FLs mentioned in your first bullet. I would also check the FL down by the starter. At least at that point you will know what FLs to get. It may take a little bit of searching to get FLs that have an appearance like the originals; if you think judging is in your future. I hope the Doctor's diagram gives the value of those FLs, not all wiring diagrams do. You want to replace the FL with one of an equal value -- and they do come in different sizes, just like fuses.TerryComment
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Re: 68 BB Fusible Link
Nice call on the Dr. Rebuild diagrams, I just ordered them. Any thoughts on where to get correct color FL wire as Lectric wont sell it you separately?Comment
68 BB Fusible Link
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