Fusible link connector

Tiny
TYBEE
  • 1994 GMC SAFARI

Electrical problem 6 cyl Two Wheel Drive Automatic 189700 miles

I'm replacing the fusible link connector at the firewall. I got a little ahead of myself by removing the connector. Now I have to figure out where each of the fusible links go. There are (2) 2.0 SQ MM and (2) 1.0 SQ MM going to 4 red wires. One is easy. It goes to the blower motor. Another I can trace to a unit(?) Mounted on the firewall below the brake master cylinder but I don't know what it is. Maybe the ECU? Two go inside to the fuse block. My question is which goes where? And is that unit under the master cylinder the ECU?

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Tuesday, June 23rd, 2009 AT 10:36 AM

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Tiny
2CARPROS KEN
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Hello,

Here is the complete power distribution wiring diagram including the fusible link locations and connections. (Below)

Please let us know if you need anything else to get the problem fixed.

Cheers, Ken

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Tuesday, November 7th, 2017 AT 11:59 AM
Tiny
AUSTIN12
  • 1997 GMC SAFARI
  • 100,000 MILES

Good a bad battery cause the fusible link to blow that comes off the
Starter and runs to the alternator replaced stater and alternator It blew
Link before I changed them and still blows link it blows link out soon has the engine turns over you can hear it blow the link out van will run off just the battery but alternator doesn't charge battery because the link blows out running out of options even checked battery cable that runs to the starter and fusible link
Wire that runs to alternator to starter and cables are not rubbing on anything
To ground it out

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Tuesday, November 7th, 2017 AT 11:59 AM (Merged)
Tiny
AUSTIN12
  • MEMBER

The fusible link wire that runs off the starter to the alternator blows has soon has the engine cranks over

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Tuesday, November 7th, 2017 AT 11:59 AM (Merged)
Tiny
AUSTIN12
  • MEMBER

When the fusible link blew out the first time I checked the alternator also and it was bad so I replaced the alternator and put a new starter on two and soon has I
Cranked the motor over again it blew the fusible link wire out again

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Tuesday, November 7th, 2017 AT 11:59 AM (Merged)
Tiny
CARADIODOC
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GM has had a huge problem with their generators since they were redesigned for the '87 model year. To reduce the large number of repeat failures, replace the battery at the same time unless it is less than about two years old. As they age, they lose their ability to dampen and absorb those spikes.

Those voltage spikes commonly damage the generator's internal diodes and voltage regulator. There's two sets of three diodes which are one-way valves for electric current flow. If one diode shorts, it will reduce the generator's maximum output to exactly one third of its rated current which isn't enough to run the entire electrical system under all conditions. In your case, if one diode in each set shorts, you will have a direct short to ground which will blow the fusible link. The thing is though, that fusible link has nothing to do with the starter system. The link is only connected to the starter terminal because it is a convenient tie point.

You should see a large spark when you connect the output wire to the generator if it is shorted, and the fusible link will blow right away, if those diodes are shorted. The fact it doesn't blow until you crank the engine suggests something else is wrong. Either you have a new fuse link that is too small in diameter, or it is connected to the wrong terminal. Fuse link wires are sold by the color of their insulation which denotes their gauge and current rating.

Before you crank the engine, measure the voltage on the generator's output terminal. You should see full battery voltage there. Once the engine is running, measure that voltage again. If you still see around 12.6 volts, the fuse link isn't blown but the generator isn't working either. You should find between 13.75 and 14.75 volts. If you do find at least 13.75 volts, measure right at the battery. You should see the same voltage at both places.

You can also unbolt the output wire from the generator, but be careful to not allow the terminal or the tools to touch ground if the battery is still connected. Try cranking the engine with that terminal disconnected. If the fuse link still blows, it is connected to the wrong terminal or there may be a problem with the battery's ground cable.

Another thing you can try is unplugging the small connector on the side, rear of the generator. That will simply turn it off. If the fuse link does not blow now, but it does as soon as you reconnect that plug with the engine running, you have a generator that has a larger capacity than the original one or the fuse link is too small. You can use a larger generator but the fuse link has to be sized accordingly and you have to be aware it is there to protect the rest of the wire which is now going to be under-sized. The generator won't deliver more current just because it has a higher current rating. (It will only deliver what the electrical system demands). The only time the larger generator will deliver more current is when the charging system is being tested under full load, or right after starting the engine and the battery is run down. Once the battery begins to charge, generator current will gradually decrease.

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Tuesday, November 7th, 2017 AT 11:59 AM (Merged)
Tiny
AUSTIN12
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Changed the battery and fixed the problem old battery
Was causing the fusible link to blow thanks for the help

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Tuesday, November 7th, 2017 AT 11:59 AM (Merged)
Tiny
AUSTIN12
  • 1997 GMC SAFARI
  • 100,000 MILES

Fusible link between alternator to starter keeps blowing on 1997 gmc safari replaced fusible link twice blows soon has I turn van on fuel pump was just changed good there be a short there I put on new starter and alternator

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Tuesday, November 7th, 2017 AT 11:59 AM (Merged)
Tiny
MADMIKE1735
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Its possible you may have a wire crossed. Double check your wiring. Also, when does it blow, when you turn the key on, or during cranking? If its during cranking, then your problem lies in the starter circuit. Should be a simple fix.

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Tuesday, November 7th, 2017 AT 11:59 AM (Merged)
Tiny
CARADIODOC
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Happy to hear it's solved, but how could the battery cause this? Was it able to crank the engine without needing a jump-start?

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Tuesday, November 7th, 2017 AT 11:59 AM (Merged)
Tiny
AUSTIN12
  • MEMBER

It blows soon has I turn the key
It will start and run with the battery up and run off the
Battery but alternator will not charge battery when fusible link
Blows and stops running soon has I pull the battery post
Off battery would a short or wire crossed on the fuel pump cause the link to blow

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Tuesday, November 7th, 2017 AT 11:59 AM (Merged)
Tiny
AUSTIN12
  • MEMBER

I had to jump start the old battery when I had it on van because it wouldn't hold a charge very long so I put a new battery in. Then I left the fusible link cable off the back of the alternator tested it with test lamp showed ok on test lamp. Then I hooked fusible link cable to alternator it didn't spark or blow the fusible link. Then I unplugged the small connector on side of alternator cranked the motor over still ok then plugged the connector back in the side of the alternator still didn't blow fusible link started engine 5 times started ok and charged ok. The battery I put in new was a older battery put I didn't have to jump start it to start the engine

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Tuesday, November 7th, 2017 AT 11:59 AM (Merged)
Tiny
MADMIKE1735
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I dont think so, I think if the fuel pump had a short, or a wire crossed, it would blow the fuse on that circuit, or not run. You can pull the fuel pump relay, and turn the key on, see if the link still blows. By pulling the relay, your "opening" the fuel pump circuit. How many wires go to your starter. Should have a purple wire- this is your ignition wire, and a positive battery cable. Right?

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Tuesday, November 7th, 2017 AT 11:59 AM (Merged)
Tiny
AUSTIN12
  • MEMBER

The only thing I can figure is the old battery had a problem with the ground side of the battery because it didn't matter when I had to jump the van off cables or jump box it would blow the fusible link

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Tuesday, November 7th, 2017 AT 11:59 AM (Merged)
Tiny
AUSTIN12
  • MEMBER

Purple wire, positive battery cable wire, and the wire from the
Back of the alternator down to the starter with the fusible link
Built in to it then the alternator has the wire down to the starter and one wire to the
Plug on the back of the alternator

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Tuesday, November 7th, 2017 AT 11:59 AM (Merged)
Tiny
AUSTIN12
  • MEMBER

I even hooked jumper cables to the new battery just to see if having to jump start the old battery was causing it and it never blew the fusible link

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Tuesday, November 7th, 2017 AT 11:59 AM (Merged)
Tiny
AUSTIN12
  • MEMBER

The battery cable to the starter and the wire from the starter to the
Alternator isn't rubbing on any thing because I traced those two wires

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Tuesday, November 7th, 2017 AT 11:59 AM (Merged)
Tiny
CARADIODOC
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Hmmm. Well; I can't explain it but I'm happy it's working.

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Tuesday, November 7th, 2017 AT 11:59 AM (Merged)
Tiny
MADMIKE1735
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What if you pull battery wire off of the alternator? It wont charge, but does it still blow the link? Once we narrow it down, we will get you fixed up.

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Tuesday, November 7th, 2017 AT 11:59 AM (Merged)
Tiny
AUSTIN12
  • MEMBER

I fixed it I changed battery thought it had a bad battery that had shorted out then I found where the plug wire that plugs into the back of the alternator that tells the alternator when to charge that wire had a spot that was bad and was rubbing on the motor causing the fusible link to blow

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Tuesday, November 7th, 2017 AT 12:00 PM (Merged)
Tiny
MADMIKE1735
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We were on the right track. Haha. Im glad you fixed it, and thanks for the update!

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Tuesday, November 7th, 2017 AT 12:00 PM (Merged)

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