I have an 85 z28, 305 tpi, 700r4. I have some wiring issues with the alternator. I have a new optima red top, new 105a alternator. Checked all of my fusable links and repaired some wiring at the starter solenoid. I have battery voltage at the red wire in the 2 wire plug. I have 7.89 vdc at the battery lug. Key on not running I have approx 2.7 vdc on the brown wire in the 2 wire plug.

car background.
just replaced the trans...ran fine then showed no voltage while running, checked alt. output, 48 vdc on multimeter. shut car down to check wiring. Got a new alt. and put in...no dice. Car is ac delete, has non ac airbox, stock fan delete. It has dual cooling fans hooked up to a toggle since the fan controller took a dump. I also gutted the ac fan relay near the battery...does it need to be there still?

Thanks for the help...need to get it sorted so I can drive it in about 2 weeks.

TIA
Josh


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Any ideas?

I was looking at the schematics and was a little confused since it shows the b+ wire going directly to the battery, but it's not...it runs the same path as the 2 wire plug to the rear of the valve cover and disappears into the loom. There is continuity between the red wire in the plug, the b+ wire and the end at the starter.

Would it help to run a cable from the battery to the alternator, or should I be looking elsewhere?

Thanks,
Josh

 

ok...well I have been plugging away at the car tonight...optima red top tested bad, so they swapped it out with a bigger one...which is good since I swap the battery between the porsche and the camaro. I connected a ground to the alternator from the battery, and again according to the schematics in the work manual, there should be a cable from the battery to the b+ lug on the alternator, so I ran one from the battery. I don't know which part fixed it or if all of it was a factor.

I am now getting 12+ volts at the red wire and the b+ lug, brown wire is getting approx 3 vdc with the ignition on, everything seems to be working good for now...we'll see if it's a permanent fix. I've also disconnected the aux tach that I put in, just in case it was back feeding somehow.

 

I have had nothing but bad experiences with Optima batteries. Im currently running a red top but only because I got it for free through a warranty swap. if it fails again on me then its getting thrown right through the front door of the shop I bought it from..

BTW, I was a 1345. Semper FI.

 

I haven't had any issues with the bigger red tops, just the little ones...I'm going to take it for a shake down run tomorrow to see if it's all worked out.

Semper Fi, 1341/49[as soon as I get done with the class, it's why I need the car running well]...among others...13 years and counting, 7 to go.