Electrical Problem - Please Advise

[Musgofasta]

Hey everyone!

 

It's been a rough weekend for me and my truck. It was getting hard to start, and the battery symbol started blinking in the message center, so I bought a new battery on Saturday. Sunday I'm cruising on the freeway, A LONG WAY from home, and the volt meter starts dropping quickly, from about 14 down to 10, then the truck cuts out, and I'm paying for 38 miles of towing.

 

Today, Monday, I swap out the alternator and charge my day-old battery, and it fires right up. Seems to right fine again, BUT...The stupid battery symbol is still blinking!!! The AutoZone Guy(also a friend) can't figure it out, and the AutoZone machine says both battery and new alternator are great. He said I can get my money back on the alternator if that's not the problem.

 

Am I missing something? Why's the red light still blinking? I feel like it's taunting me.

 

Vital Stats:

2001 Silverado 1500

4.8L V8 Automatic

just short of 39000 miles,

and no warranty left

 

Thanks for any advise

Musgofasta

[99-2door]

battery cable or alternator. That's about all it can be.

[Musgofasta]

well the alternato is brand new this morning, and the cables visually appear ok and tight everywhere I see. Still no word from the dealer. Not driving far so AAA will tow me for free if this happens again!

 

How do I test for bad cables?

[AirForceAngler]

Cables can look fine, but have corrosion inside the insulation on the terminal ends.

[71GMC_3/4T]

You may have gotten a bad alternator. Was it remanufactured?

 

If you measure the volts out of the back of the alternator (using the alternator frame as the ground reference) it should read 14 to 15 Volts DC. If it doesn't, your alternator is possibly bad. It could also be the wiring to the small plug on the alternator.

 

If the alternator checks out, measure the voltage from the alternator output (stud on back with big wire connected to it) to the + terminal of the battery. You should read very near zero volts. Also, measure the voltage from the alternator frame to the - terminal of the battery. Again, you should read very near zero volts. If you have any voltage drop on these measurements, you have a bad cable or terminal.

[Musgofasta]

Got it back from the dealership a minute ago. The alternator functions properly, but it's plug for the PCM is broken/defective/whatever, resulting in a mistaken problem.

 

Yes it was remanufactured, but has a lifetime warranty. I'm getting a replacement one tomorrow morning. All of the cables checked out fine, also the grounds for the connections.

 

It was an expensive problem!

 

Battery $75

Alternator $150

38 mile tow home $180

Dealer diagnosis $77

Lesson to not drive an out-of-warranty vehicle: Priceless

 

Thanks everyone,

Musgofasta