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Charging issue, not Cadillac


Delta

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Hello all, not my Caddy this time. 99 F-250, bought it last Sunday, everything was good. Monday, noticed charging light came on intermittently, lights flickering/pulsating. Got a reman alternator, put that in, symptoms didnt go away, matter of fact, they got worse. Drive truck around town, ok, get on the highway, bring it up to speed, charging needle pins out at max 18+ charge, rev a little, and it goes back down to normal. I cleaned the ground on the battery, new terminal, cleaned brushed ground connections, including adding dielectric grease, problem still exists.

Now today/tonight, go out to start the truck, dead battery, probably fried with the overcharge. Jump it, starts up, no overcharge, but then again, didnt rev it up. Yanked the battery, put in a brand new battery, start the truck, immediately goes to overcharge, pinning the needle to over 18+ volts. Shut it down, yanked the alternator, going to have it tested at autozone.

Any ideas? Its driving me batsh**. I can only assume its the reman alternator/regulator inside the alternator that would be causing this or am I chasing something totally different? I know you can get a bad part right out of the gate.

Thanks in advance, !!!

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With the lights flickering, you may be looking at a battery cable problem. If the regulator is known good, i.e. inside the alternator or replaced with a known good regulator, I would look at cables and connections. Typical culprits include band ground from the battery or bad engine ground strap, more than one cable end in the positive battery cable and one of them inside the red plastic not making good contact, broken strands in the cable to the alternator armature or field, shorted field contacts, or mis-connected alternator field connections. Trying to wire a two-wire or three-wire system with a one-wire adapter can also cause overcharging problems.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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Hello all, not my Caddy this time. 99 F-250, bought it last Sunday, everything was good. Monday, noticed charging light came on intermittently, lights flickering/pulsating. Got a reman alternator, put that in, symptoms didnt go away, matter of fact, they got worse. Drive truck around town, ok, get on the highway, bring it up to speed, charging needle pins out at max 18+ charge, rev a little, and it goes back down to normal. I cleaned the ground on the battery, new terminal, cleaned brushed ground connections, including adding dielectric grease, problem still exists.

Now today/tonight, go out to start the truck, dead battery, probably fried with the overcharge. Jump it, starts up, no overcharge, but then again, didnt rev it up. Yanked the battery, put in a brand new battery, start the truck, immediately goes to overcharge, pinning the needle to over 18+ volts. Shut it down, yanked the alternator, going to have it tested at autozone.

Any ideas? Its driving me batsh**. I can only assume its the reman alternator/regulator inside the alternator that would be causing this or am I chasing something totally different? I know you can get a bad part right out of the gate.

Thanks in advance, !!!

I had an issue with a truck once. What was happening was that the signal cable from the alternator back to the battery wasn't good. What this was causing was the alternator to see the battery discharged hence the regulator would kick high voltage out to try and re-charge it. Once we replaced this cable everything went back to good.

What you could try (I believe ford still allows this), is to turn the truck on, disconnect the battery and check with a voltmeter the battery connectors to see if they show the same voltage you get on the inner meter. That would be a start...

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What you could try (I believe ford still allows this), is to turn the truck on, disconnect the battery and check with a voltmeter the battery connectors to see if they show the same voltage you get on the inner meter. That would be a start...

Do not disconnect the battery with the engine running - that will destroy the regulator and/or diodes in the alternator.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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What you could try (I believe ford still allows this), is to turn the truck on, disconnect the battery and check with a voltmeter the battery connectors to see if they show the same voltage you get on the inner meter. That would be a start...

Do not disconnect the battery with the engine running - that will destroy the regulator and/or diodes in the alternator.

DAAANG.. Thanks KHE, and sooorry Delta. I could've swore I saw 89 on the trucks year. KHE is absolutely right. If you have the truck working then disconecting the battery could fry the regulator or even the ECM.

Sorry again! I'll be extra careful next posts

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Ripple voltage or (AC voltage) can be measured by switching your DMM to AC and connecting the black lead to a good ground and the red lead to the "BAT" terminal on the back of the alternator, (not at the battery). A good alternator should measure less than .5 VAC with the engine running. A higher reading indicates damaged alternator diodes.

The saddest thing in life is wasted talent

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Hi yall, well, went to the electric service place where I got it, and it was bad (the alternator). As soon as he put it on the machine, it was overcharging big time. Got another, and put it in the truck, and all is good (right now). Gonna get a new battery tomorrow and put that it and go from there. I think all the time it was a bad alternator from the start :fighting0025::wacko:

Thanks for your help!!!!

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I call those altercators.

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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This thing has been driving me crazy for about a week. You wouldnt believe it, driving down the highway at night from work, headlights flickering/pulsing, then BRIGHT!. I really dont know how the hell all the bulbs didnt blow out, they were that bright. It was like a supernova...

So, you CAN get a bad part out of the box.

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You have a loose or broken sense wire or on that truck a blown fuse on the sense wire of the regulator it does not detect voltage so regulator goes wide open then fries it sounds like your second alternator could also be bad out of the box cheap advanced auto zone alternators I insist on having tested out of the box before I leave the store because one time I got one for a 99 lumina ltz installed it on the car and it put out 31 volts dc and cooked everything on my car I got the manufacturer to pay for the damage as i proved they had pins soldered incorrectly inside unit

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