Hello all,

1978 Caprice, 2004 LY7 Avalanche Engine/Trans. I've tried to read through other threads to see how they resolved their issues.

I'm going to use the original wiring from my '78 Caprice to power the starter, but not the alternator. On the '78 Caprice there are 4 wires that originally connected to the starter. One from the battery. One is for the solenoid. The other two were spliced together, and from what I can tell from the original wiring diagrams, are used to power the some items on the fuse box. I'm going to leave 3 of these wires and replace the one from the starter to the battery with the '04 starter to battery wire (it seems to be in better shape and has a handy junction box). The original wire that went to the original alternator stud from the starter on the 78 caprice is about a 10 gauge and went down and spliced into the other wires that went to the starter. The 04 Avalanche wire on the 04 alternator stud is a much larger wire and says "fusible link" on it. I assume that this is because there are many more amps being used on a 2004 avalanche than was used with a 78 caprice. This larger 04 wire also went to a junction box on the wire that goes from the battery to the starter, which I've read is a better way to connect to the battery, instead of connecting to the starter like the Caprice did. My thinking is to run a wire from the 04 avalanche alternator stud over to the positive battery wire junction box, just like the original 04 harness did. Since the original wire isn't long enough, I'll have to get another one, which wont' be a fusible link, so I'll also add in a fuse or a breaker.

To sum up, I'll remove the old, small 10 gauge wire that used to go between the alternator stud and starter in the 78 caprice and replace it with a larger wire that will go from the new alternator stud to the battery cable junction box and I'll add a fuse or breaker in between (i'll be using the '04 battery cable that goes to the starter because it has a junction box built in from the factory, which is very useful). I'll leave all other wiring the same. Does this sound correct? I've made the picture below to try to help: Thanks

 

 

For simplicity... Use #4 gauge wire, with a fusible link within the first 6" of where it ties into the battery (+). O'reillys auto parts sells copper terminals that will accept the #4 gauge wire, and have a small 5/16" hole on the end that is a perfect fit for the stud on the back of the alternator. Look for them by the battery section. They also sell fusible links that can be soldered into the charge wire. They also sell the #4 gauge wire by the foot so you can buy exactly the length that you want.

There are two wires coming out of the PCM that will need to attach to the alternator. You can delete all of the factory wiring. Late model alternators put out as little as 105AMPS, then 145A, and then some even higher than that... If you are running electric fans, or dual electric fans, and A/C, and a stereo with amp(s), the larger charge wire is just good insurance.

 

Thanks buggy. I'm not very savvy on amp loads. Is there a reason a fusible link is preferred to a fuse? I assume there must be since the factory used this method.

 

I would use either midi fuse or circuit breaker for the alternator wire, instead of fusible link. IMO, what we have today in circuit protection is far more superior to what's was available 30-40 years ago.