Alternator/truck wiring

[klittle1417]

Perhaps someone can answer a question about alternator and wiring. I have a 97 K1500 truck as well as a 99 K1500 and K2500 suburban. The two suburbans have a junction/fuse block on the radiator shroud where the power wire comes from the driver's side and then the wire from the alternator joins it and a wire leads to the battery.

The 97 K1500 truck does not have this. Both wires go to the battery. I do know the two suburbans have 140 amp alternators while the truck has the 105 amp.

Is this junction/fuse block there because of the higher amperage alternator?

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[klittle1417]

Perhaps someone can answer a question about alternator and wiring. I have a 97 K1500 truck as well as a 99 K1500 and K2500 suburban. The two suburbans have a junction/fuse block on the radiator shroud where the power wire comes from the driver's side and then the wire from the alternator joins it and a wire leads to the battery.

The 97 K1500 truck does not have this. Both wires go to the battery. I do know the two suburbans have 140 amp alternators while the truck has the 105 amp.

Is this junction/fuse block there because of the higher amperage alternator?

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Anyone?

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[Urambo Tauro]

Not sure. Does it look stock, or do you suppose a previous owner might have put it in (for a sound system?)?

 

[delta_p]

It sounds like the junction box is a battery isolator or solenoid to run an auxiliary battery, normally placed on the driver side where sometimes the spare compartment box is mounted on some models. The isolator allows both batteries to be charged to charged by the alternator but if stopped and running off the auxiliary battery (like lighting your campsite or something) it will isolate the main battery from the auxiliary at a point so as not to drain it all down. It can also allow the auxiliary batter to supply the main battery a boost for starting if needed. I thought some suburbans came this way.

 

[klittle1417]

It looks stock on both Suburbans and neither have dual batteries. The dealer found it in the parts diagram but had no explanation for it being there.

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[Steve A]

That fuse on the burb's are probably there taking the place of the fusible link on the smaller alternator on the truck. I have never seen fusible link heavy enough to protect the 140 amp output of the bigger alternators.

 

[Ken K]

For the OEM 97 charging system schematic shows a #5 RUST colored fusible link between the alternator and the battery from the B+ terminal. I have no photo showing what bracket, connector or device for attachment. It obviously is protection from the alternator to the battery. The battery is charged by the alternator, but the alternator supplies current to the entire vehicle when in use. Whether it is an aftermarket "MAXI" type fuse or fusible link, it serves the same function. With my "Stand alone" GM service information on CD, in 99 K-Pickup, they show much more, including dual batteries (Opt), 175 amp MEGA fuse & #5 RUST fusible link, depending on "Police package", 2WD, 4WD options. It is feed into the underhood fuse/relay center. I did not look at 98 models.
You can use alternatorman.com to ID your alternator and it's OEM output and choose the correct Fuse.

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[redfishsc]

My 1999 K1500 and C1500 Suburbans both had the wussy 105 amp alternator, and neither of them had this junction that you refer to, both have a hot lead coming from the fuse box in front of the driver's side under the hood.

I upgraded the C1500 (the family hauler) to a 140 amp since I tow with it on occasion and have had times that the 105 could not keep up (both HVAC fans on full, headlights on)