Hello

I noticed recently that on one of my trucks the (aftermarket) volt gauge is floating around the 15-16V range especially in the morning when engine is in high idle. Turning the blower motor on will pull it back down to 14.5V until I start driving. I got my DMM out to confirm and at the battery which I got about 15.5 volts. I made sure the remote sensing wire didn't have excessive voltage drop (only .2 or .3 difference). While I was looking around I noticed my ignition module was leaking goo/tar so, I purchased a replacement. I not sure if that happened because of it's age or the voltage.

I pulled the alternator and had it tested at two different auto part stores. The first said it was fine and was putting out 14.5 volts. The second said it was putting out 15V but, their computerized tester still passed it as good. I got a replacement under lifetime warranty (reman part). Just for giggles I had the replacement unit tested... it was worse. Putting out 15.3 volts.

I'm not sure what to think.

Is this normal? I personally don't like to see a voltage higher than 14.7 Is it because I'm dealing with reman parts? Both units are 3 wire SI12 78amps under the Ultima name so.. oreilly house brand.

My plan tonight is:

• Install the alternator
• Install wire to alternator ground lug
• Install the ignition module
• check the resistance of the dual resistor ballast

But, I'll recheck here before I proceed.

Let me know what you think

Thanks

 

Alright, got the above done. No change still 15-16V at startup.

I ran a new 14ga wire for the remote voltage sensing to the hot block. That fixed it. I'm maintaining 14.5V at the battery. However, there was a price; The alternator doesn't compensate as well as before for electric loads in the cab now (headlights, heater motor).

Voltage sense was originally hooked up to the key fed wire that ran the stock external voltage regulator. I take it the fact this is happening means my wiring harness is deteriorating?

I still have some work to do. I need to add an inline fuse or fusible link for that new sense wire. I believe I need a 18ga fusible link? If anyone knows a part number for the auto part store let me know.

 

Just got back from a test drive. It's not too bad. Engine seems to run slightly better.

I think it will get better when I get around to installing a relay box but, that won't be until next summer for this truck.

The replacement alternator seems to be a lower quality reman as it "whines/whirs" at traffic stops.

I'm going to bed.

 

14.5 is ok in my book...

 

Agreed.

I decided to go with a 18ga fusible link to protect the 14ga wire. I'm sure a 1 to 5 amp inline fuse would be fine also, but I don't want to risk a fuse blowing and then the alternator kicking into maximum overdrive.

My local napa only keeps 14 and 16 links in stock but, the following part number should fix that:

• Primary Wire Fusible Link 18 ga.
• BEL 784690

One thing I've learned since I've started working on my vehicle is to research your own part numbers. Especially when doing weird stuff to your vehicle like me. It makes it easier for everyone.
It also takes care of that one guy. You know the one. The parts clerk that won't help you because their convinced what your asking for doesn't exist.

 

And Keep all those part numbers you use in a Car Ledger with you notes....

 

absolutely