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need help/suggestions car died

 
1984owner
I love my Chevy Chevette!
Posts: 3
Joined: 08/12
Posted: 08/24/12 03:19 AM

I have a 1984 vette. I was driving it to work today and I had the rear defroster on, windshield wipers and the heater on the windshield to get rid of the condensation from the humidity. The next thing I knew I went to turn into a gas station and I heard a pop in the fuse box and everything died except the car battery. I tried to restart it and I have nothing I can't even use the 4 ways or roll up the Windows. the only thing that works are the headlights and tail lights. I checked the fuses and found the defroster fuse melted and all the other fuses ok. Any ideas?  

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waynep71222
My first time was in a Chevy
Posts: 181
Joined: 04/12
Posted: 08/24/12 04:03 AM

you blew the 16 gauge  fusible link  on top of the starter solenoid..

i don't have a corvette wiring diagram posted but i do have a 77 to 80 chevy pick up diagram and its wired the same way...

look at the 16 gauge fusible link right at the starter...

77 80 Chevytruck Fusible Links

i would bet that if you take a test light and probe the output terminal on the back of the alternator that you have power on the back side... but if you probe the red wire into the side. that you have none..  that indicates that the smaller of the 2 fusible links has done its job and protected your cars harness..

here is where the fusible links are hidden...
Starterwiring 1

before you crawl under the car.. you should know that the 16 gauge fusible link has 2 wires coming off it..  the pu diagram shows a pair of 3mm/12 gauge wires.. but the C4 charging diagram i have shows that there is a 12 guage and a 10 gauge wire coming off the end of the fusible link..   you will want to assemble a fusible link on your work bench with short staggered sections of 10 and 12 gauge wiring so you can use conventional sized crimp terminals.. instead of trying to fight a 12 and a 10 gauge into a yellow and then try to crimp the 16 gauge in the other side..

i have taken to using european style terminal block sections to clamp the fusible link to the wire.. every radio shack has them..  it depends on how much room you have..   and the 84 has a little more room than the image shown..

warning.. THERE IS A LOT OF PLACES to check before you hook the battery back up...  i have had this issue on other GM cars... i am not saying that just replacing the fusible link will not cure the problem. i am saying that i want you to Verify some of the other failure issues are not going to cause a LOSS of your corvette to an electrical fire...

more to come...  

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waynep71222
My first time was in a Chevy
Posts: 181
Joined: 04/12
Posted: 08/24/12 04:06 AM

oh... PLEASE do not increase the size of the 16 gauge fusible link.. it worked for 28 years... and when called on.. it protected the harness..  

if you change the fusible link size... if the load gets too much. you will burn your harness before the fusible link burns...


also.. PLEASE.. probe the output terminal of the alternator..  you should have battery power there..

please probe the red wire going in the side of the alternator..   if you DON"T GET POWER on the red wire into the side connector.. then you HAVE a blown fusible link at the starter solenoid...

if you have POWER ON BOTH.. then you have a blown fusible link or burned connection elsewhere in the system..

this test might take one minute to do.. its quick.. it proves if the fusible link at the starter is burned or NOT...

the reason the headlights still work is they are powered from the same top post of the starter solenoid on their own 16 gauge fusible link....  

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waynep71222
My first time was in a Chevy
Posts: 181
Joined: 04/12
Posted: 08/24/12 04:47 AM

other things i would like you to check...

drop the knee pad.. and probably have to bend your self double..

examine the ignition switch connector side... its probably easier to just replace it.. they are under 20 bucks at every parts store..

LS309 at AZ stores...

Ls309ignitionswitchpinout

the reason i am saying this.. is the heater and AC even the defroster power comes through the  I3 pin.. with the power for that terminal alone coming from the B3 terminal..

the problem is when the loads get GREAT the terminals get hot.. and the various components melt...

this is the AZ duralast 263 ignition switch connector bodies.



this is also under 15 bucks and comes with a few sections to replace damaged terminals..  these terminals are really easy to extract from the connector body once it's disconnected from ignition switch.. just push in slightly and use a tiny screw driver to depress the tab. then pull...     lift the tab back up before inserting it back in.. so it will latch..

i have found these connector bodies melted from the heat of an over load... i am not saying that these will be an issue with your car.. but i would really like you to examine them prior to hooking the battery back up..  

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waynep71222
My first time was in a Chevy
Posts: 181
Joined: 04/12
Posted: 08/24/12 05:02 AM

lastly.. back to the fusible link.. with 2 wires protected by only one fusible link...  the 12 gauge wire to the side of the alternator is the voltage regulator SENSE wire.. it lets the voltage regulator know how much load there is on the system and it can increase the alternators output..  the thick wire is to increase electron flow to this connection.. increases the speed of the charging system response to changes in load..

fusible link sizing to protect the circuit.. is usually 4 sizes smaller than the wire its protecting..

so a 10 gauge wire gets a 14 gauge fusible link...
a 12 gauge wire gets a 16 gauge fusible link..

the corvette wiring diagram shows a 1.0MM fusible link..
fusible links come in metric wire sizes.. the chart is as close ..

i have also heard of problems with the blower resistor/or power module if you have electronic climate control giving problems..  burning the connectors into the defroster fan relay...

there have also been problems with the rear window defroster relay... don't forget.. the outside mirrors also seem to be heated by the same rear window defroster circuit..

you may want to stop by a harbor freight tools store and buy one of these plug in amp testers..

Image 14146

30 Amp Automotive Fuse Circuit Tester
Cen-Tech - Item#67724  10 bucks on sale..

also similar items through napa stores at about 30 bucks..

this is the tester for the smaller fuses used in newer models

Image 14147

you can verify the amount of current being pulled through the fuse location ..

please pick up an assortment of proper sized fuses.. start with probably a 25 amp fuse in the side of this tool.. use american made fuses.. not harbor freight fuses.. or cheep fuses.  

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1984owner
I love my Chevy Chevette!
Posts: 3
Joined: 08/12
Posted: 08/26/12 07:55 AM

Thank you for.all of.this info. As soon as I can I'll check it out and let you know what happens.  

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1984owner
I love my Chevy Chevette!
Posts: 3
Joined: 08/12
Posted: 09/03/12 06:14 AM

Ok so I found the problem and the fuseable link is intact. It looks like the wire after the link got burned threw by the exhaust. what do you suggest I do?  

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waynep71222
My first time was in a Chevy
Posts: 181
Joined: 04/12
Posted: 09/03/12 05:42 PM

replace with like sized wire...   don't use the cheep wire in bubble packs from the displays at most parts stores..


truck electrical alternator and starter electrical shops usually have the best quality wire...

you do have several options.. snag some from a gm in the junk yard.. it does not have to come from the starter harness...  just someplace where its not burned..   millions of cars to choose from...

replace the exhaust flange gaskets...   or check for loose or cracked exhaust manifolds...

i have taken to using sections of the orange silicone jacked fiberglass lined FLAME proof tubing...   its over 100 bucks for 6 or 10 foot...   i picked it up at a surplus aircraft parts store a long time ago.. its still available...

you can get orange silicone self vulcanizing tape to wrap the harness areas where they are exposed... grainger sells it...

i would bet that the fusible link also blew... as when the other wire burns through the fusible link does it job to limit damage..

last two options...   and NOT easy to get...     teflon insulated wire... or braided fiberglass insulated wire..  used mostly in air craft applications.. but also used in some high temp applications..     both are kinda hard to get.. even though i live in los angeles..  which is more than a 2 horse town now a days..


you will probably need one purple wire...    10 gauge...

and 3 red wires 10 gauge.. and a few feet of each...

so you can replace all the segments to the starter...

you might want to stop by a radio shack..  pick up several sizes of their european style terminal blocks..  using individual sections to connect the 14 or 16 gauge fusible link to the 10 gauge wiring...  makes it easy to replace the fusible link if you make a short section of conventional wire for each.. so the fusible link is not directly at the ring terminal..  then its just a tiny screw driver to release the fusible link..  

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