Charging issue

[ditch_dawg]

Just got a call from a friend. His neighbors truck is having alternator issues.

New alt, new batts and new starter. Turns out old alt was checked and found to be ok.

While running large wire is just showing battery voltage 11.8V, normally I would see 13.8 to 14 volts on my old truck.

The truck will run for a brief period and die. Pretty sure there's not enough juice to keep it going. When it dies the relays under the dash (maybe GEM) click like crazy. I remember seeing a similar issue over an a different site, but I'll be dipped if I can find it.

Getting all this info over the phone so bear with me.

I told him to make sure the grounds were clean and tight. Is the Alt self excited or does it need a signal from the ECM?

Any help would be greatly appreciated!

Gerald

 

[Arisley]

Check all the grounds. There are a few of them. Check all the cables. Pull back insulation, if you see any corrosion. Replace them. Positive and negative.

 

[CSIPSD]

Fuse is blown... Not sure where it is on each year, but there is a fuse that will blow and then the alt will not get the signal to charge.

Happened to me several years ago.

 

[Diezel Dawg]

When you have the key on and don't start, is the battery light dimmer than all the other dash lights? If it is, change out that bulb for the battery light. That was my problem and it fixed it.

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