Electrical Woes

chiefsfan · April 11, 2009

Hey guys, I'm hoping you all can help with an electrical problem I'm having. I recently bought a 04 CC 8.1/allison. A couple of weeks into owning this thing, the voltage gauge started reading 19 when I was driving around and set off the airbag light. I figured the regulator had gone bad, no big deal. The alternator appeared to be original, judging from the delphi logo and the way it was rusted into the mounts. I disconnected the battery to protect the new alternator when I installed it. After changing the alternator, everything was back to good, and I had consistent 14 volt readings for another couple of weeks. Airbag light was still on occasionally though.

Fired it up again today, and it's showing high voltage again. I'm at a loss as to what to replace or do to get this thing right. Any ideas? Obviously, I'm not thrilled with the idea that something is frying regulators left and right.

By the way, I love this forum. I've learned a ton about this truck already since buying it. Thanks in advance for your insights.

Griptruk · April 12, 2009

this is a total shot in the dark, and is kind of out the window if the voltage regulator is on the alternator.

If it isn't then I was thinking that maybe there is something making the the regulator read wrong, like a frayed wire or a short.

Perhaps you could put a voltage tester at the regulator and see if there is a difference to what the dash gauge is reading.

Sounds a little simplistic I guess.

bill190 · April 12, 2009

I had some luck searching google.com for...

auto "voltage regulator" "19 volts"

Wiring with loose or broken connections to an alternator, voltage regulator, or battery seem to be mentioned along with this problem.

Might want to disconnect each wire at one end, connect an ohm meter to both ends of the wire, then wiggle it to see if it continues to conduct well.

Also might want to check the main ground wires to the engine and body.

Here is the above google search if you want to read more...

http://www.google.com/search?hl=en&saf...amp;btnG=Search

chiefsfan · April 12, 2009

Thanks guys. I rechecked all the grounds yesterday and disconnected the battery for about an hour. I also connected both battery leads to the ground (pavement) to discharge any remaining stored electricity in the circuit.

Reconnected after a while and again have 14V. The truck ran great all day today. If it happens again, I'm going to change out the battery, since it looks like that's the next, most likely bad link.

It's funny, but every vehicle I've ever bought used has needed a new battery or alternator in the first month of ownership. Hopefully, I've got it licked now. I'll try to post some pictures sometime soon.

bill190 · April 13, 2009

If you were to open a car door, the dome light turning on would get rid of any remaining electricity (if any). So disconnect battery, open door, and if dome light is off, then all the electricity is gone!

As to "ground" and electrical wiring. This is a bit confusing I must admit... Anyway when it comes to vehicles, "ground" refers to the metal body of the vehicle or the entire metal parts of the engine. This is also "-" or the negative (black) wire on the battery and commonly black wires would be "ground" wires (but not always).

I guess this is a term they started using way back when before there were any cars. And the terminology stuck. Like "dialing" a phone number. These days it is more like "pressing" a phone number!

As to checking the wires, you may have seen very old vehicles with the battery cable barely hanging on to the battery connector and a very bad connection. Or frayed wires with just a few strands still there. These would be the bad connections I was talking about above. There is usually a large black wire going to the engine. This is the "ground" to the engine and possibly to the alternator as well. If the bolts holding this wire were loose or the wire cut or frayed, then that could be a problem because it would not be connecting very well. Or there may be other wires with bad connections. These would have that "old car amazing it runs" look as opposed to "brand new car all wiring in good condition" look.

TexasAl · April 13, 2009

From what you are saying, it sounds like it may be a bad battery. The alternator is being overworked, "trying" to charge the battery, but since the battery probably has a bad cell, the alternator can never get there, eventually frying it. Get the battery checked out at a parts store.

Al