89REATTAJIM

Fuse getting HOT

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Found that my 20 Amp "Hazard" fuse gets extremely hot whenever the 4 ways or brakes are applied. Am assuming this to be a bad ground. Any suggestions on where to look?   Jim

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a bad ground is the first place i'd look. do you have a FSM for checking the wiring diagrams?

 

i'm not sure where the ground for that is (others will). the first place i'd look is here: http://reattaowner.com/roj/component/content/article/62-electrical-system/other-electrical/224-ground-terminals-junction-box-location

 

but the ground problem may be possibly may be under one of the seats, or the rear brake lights having a bare positive wire hitting the metal (ground).

 

wish i could help more...

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Do the brake lights work properly? Are any of the bulbs dim?

 

I think I would start by pulling the taillight out to inspect all the sockets for problems. I don't see how a loose or dirty ground would cause the fuse to overheat. A hot wire partially going to ground could. If a hot wire was completely shorted it should blow the fuse.

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Before you go all crazy chasing things that are most likely not there. replace the fuse and clean the contacts a bit.

Then keep in mind the fuse is the designed week point and should be warmer than the rest of the circuit. With that in mind the brake lights alone pull roughly 16 amps [2 amps x (3 tail lights + 2 high mount)];17.6 amps by the two charts I found for the 2057 bulbs and probably more considering the two high mount bulbs. So if your fuse is warm it is most likely supposed to be, as it is designed to break/burn with only an other 2.4 amps of current.

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Just to get a baseline on how warm that fuse should get I went out and checked the fuse temp on my '88 model with my infrared digital thermometer. The car had been sitting in the garage all day without being driven. The initial temp was 84.6*, same as the temperature in the garage. Then I held my brake pedal down for 5 minutes straight so the brake lights would stay on. When I tested again I got 85.9*. I couldn't detect the difference with my hand. It's possible your '89 model could be wired differently causing it to get warmer but I doubt it.

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Heat builds AT THE BAD CONNECTION. The fuse holder is the problem. I have seen inline 30 amp fuse holders burn up completely and the fuse was still good. It could be corrosion or even one solder joint at the fuse contact spade.  

 

Once, I had my 10 amp battery charger get one of the battery lead wires cut. I skinned it back and twisted the two ends back together. Thereafter, when I used the charger, the connection got too hot to touch. After twisting and soldering the connection, no more heat.

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Heat builds AT THE BAD CONNECTION. The fuse holder is the problem. I have seen inline 30 amp fuse holders burn up completely and the fuse was still good. It could be corrosion or even one solder joint at the fuse contact spade.  

 

Once, I had my 10 amp battery charger get one of the battery lead wires cut. I skinned it back and twisted the two ends back together. Thereafter, when I used the charger, the connection got too hot to touch. After twisting and soldering the connection, no more heat.

Makes sense to me. I've never had that happen but a bad connection causes resistance and resistance generates heat.

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Thank all of you for replies, I think Texas John's idea is probably correct. Now, how does the fuse box get removed for repair? Can I splice into the wires elsewhere and put the fuse in at another location? Looks like this is turning into a major project!

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Anyone have pix or instructions to remove the rear cover of the '89 fuse block? Haven't been able to remove the block from car, but do have it loose enough to repair the wiring if the cover was off.

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First question: is it the fuse or the fuse block that is getting hot ? Have you tried another fuse ? Is one end hotter than the other ?

Agree: bad connection = resistance = heat. It also reduces the current flow so the fuse may not blow. Bad connections particularly wth aluminum wires is a major cause of home fires.

Have you looked over section 8A-11 in the FSM ? Fuse 6 is on page 5.

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First question: is it the fuse or the fuse block that is getting hot ? Have you tried another fuse ? Is one end hotter than the other ?

Agree: bad connection = resistance = heat. It also reduces the current flow so the fuse may not blow. Bad connections particularly wth aluminum wires is a major cause of home fires.

Have you looked over section 8A-11 in the FSM ? Fuse 6 is on page 5.

   Thanks, it is the FUSE getting hot. The right side of fuse(looking at front of fuse block), where pink/white stripe wire comes in, melted, the spade detached and remained in the block. I cleaned the damaged terminal as best I could, put a new fuse in. With the new fuse, if I hold the brake pedal to lite the bulbs, the new fuse gets very hot in just a few seconds. Have checked all stop lite bulbs & sockets (including high level bulbs), do not see any problems. My next step is to snip the two wires going to the fuse and soldering in a new fuse terminal away from the block. 

    Yes, viewed info in FSM. Didn't lead me anywhere.

    Any thoughts whether this may be a "Wiring under passenger seat" problem?  Really don't want to go that route unless absolutely necessary.

   Again, thank you for your help, will report further when I install the new terminal.

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Have you tried pulling the fuse and checking the current ? Sholdn't be over 10A.

Could be the connector geting hot from a bad connection in the fuse block.

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   Fixed at last! Can't say I'm proud of the way it had to be done, but it works. Biggest problem was getting the fuse block pried out far enough to remove the rear cover (another PITA). Cover off, was able to snip the two wires going to the fuse and soldering in a new fuse holder. It ain't purdy, but it works. Have no idea what could have caused the problem, could have been developing for months.

  Thank you all for your replies.. Jim :D 

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