99 Sierra Alternator upgrade

[old99]

I have a 99 Sierra 4x4 with the 5.3 with the new body style.

The other day I started the truck and the red BAT. light did not go off. I looked at the volt gauge and it was at about 10 started down the road and it jumped to 14 and the light went off.

Went to the parts store and had the system tested and all was OK.

Drove 15 miles and all was good. Shut the truck off at the store. 15 minutes later started it up and the red light was on and the volts were low. Limped it home and it died in my driveway.

From past experience decided it was the alternator.

Drove the wife's car to parts store, got new alt. only to find that it was to large. 4 letter word!!!!!!!

Did some looking on the net and found that my truck had a 105 amp alt and I could use the larger 130 amp one if I used a longer belt. So I decide to get the longer belt and "upgrade" to the 130 amp alt.

Works great however after just a couple of minutes the red bat. light comes back on.

My old alt. had a 4pin plug and the new alt. had the same. However my harness only has a single wire coming out of it.

Will this work????? Could I have cooked my old battery or????

I have in the past found something regarding the number of wires off of the alt. but cant find the post now.

Any ideas or advice would be great!

Thanks

[Chris]

You can use any of the pickup alts from that tear range with a gas v8 and same number of wires. You could use the 160 amp from a 6.0 v8 2500hd with plow prep. I use an aftermarket the 300 amp that is the same approximate size as the 160.

[old99]

That is what I thought. So I'm thinking my battery is toast.

Even with the RED bat. light on after the new alternator install the truck runs GREAT but I don't want to cause any trouble with the PCM.

Thinking I will buy a new bat in the AM.

Any other info will be appreciated

Thanks.

[old99]

Chris,

 

Does your 4 pin plug have more than one wire coming out of it?

I think your right (and I have found the same info) but I also keep finding conflicting things regarding the single wire plug.

Especially around the 99 year.

Thanks

[Chris]

I have a 4 pin with 3 wires.

[jonstreet]

Lol my trucks lights go on and off if I smack the side of the dash they stay on for a couple of days maybe this is what u r having. Don't trust all those guys at auto stores with the test box I'm one of them I see a lot of guys I work with selling bat. When they shouldnot we get paid 8 bucks an hr. Do trust someone who gets paid the same as McDonald's workers to fix your car we just sell parts lol some guys have hands on experience but not many.

[old99]

Thanks Jonstreet,

I still have not had a chance to solve this.

We live 30 miles from a town that has a parts store and I have had to use the truck for work.

I start the thing and just like it should the red bat. light goes out after a couple of seconds then comes back on and stays on. It's obviously working because the volts are up and it keeps the bat. up just hope I'm not harming anything else.