Alternator surging or something else?

[ParkerFly]

On my truck sometimes the voltmeter on the dash will wiggle and not sit still when the truck is running. It's not affected by rpms and when it does it the lights constantly dim and brighten a little. This alternator is relatively new but I'm pretty sure it did it with the old one some too. I'm never around something to check it with when it's doing it but this morning when it wasn't messing up I checked and it was putting out a steady 14.53 volts. Is this an alternator issue or something else I need to check?

 

[dillpurdy92]

On my truck sometimes the voltmeter on the dash will wiggle and not sit still when the truck is running. It's not affected by rpms and when it does it the lights constantly dim and brighten a little. This alternator is relatively new but I'm pretty sure it did it with the old one some too. I'm never around something to check it with when it's doing it but this morning when it wasn't messing up I checked and it was putting out a steady 14.53 volts. Is this an alternator issue or something else I need to check?

Mine does this also. But goes away after about 20 seconds

1994.5 CCLB zf5

 

[ParkerFly]

Mine doesn't seem to have any rhyme or reason to it. It may do it after it's been running a while or right after it starts. Once it starts doing it, it does it for a long time or until the truck is turned off.

 

[dillpurdy92]

Mine doesn't seem to have any rhyme or reason to it. It may do it after it's been running a while or right after it starts. Once it starts doing it, it does it for a long time or until the truck is turned off.

Hhhmmm i have no idea man. Ive some guys on her say that its the EBPV

1994.5 CCLB zf5

 

[ParkerFly]

That's long gone on mine I've got an h2e.

 

[dillpurdy92]

That's long gone on mine I've got an h2e.

You said its a new alt? Check all your grounds also

1994.5 CCLB zf5

 

[psmike]

mine does it too.. heard an was told its the belt slipping.. an once it warms up its fine..

 

[Bair]

Just replaced my alternator for that reason. Had it tested and the voltage regulator was bad. New one is rock steady.


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[jschildm]

I believe a tuner told me once that if the voltage is above 14.2V (I think that was the value), on some trucks, the glow plugs will cycle off and on. Mine does this, especially if I start driving while the glow plugs are still on. Once the GP system shuts off for good, its rock steady.

 

[Patrick Feeley]

When mine had those symptoms, I pulled the alternator and removed the regulator. The slip ring contacts were bad. New alternator fixed that problem. Cheers!

 

[thatdude]

I had this issue on my factory alternator. Got an autozone one, still did it. Got a DC power alternator and it stopped... So I'm going to say voltage regulator.

 

[Peroni]

My truck would do this until the glow plugs go off or I turn on the headlights and blower. Drove me nuts thinking I had an electrical problem. Had my tuner adjust the glow plug duty cycle to 15V and no more surging. It didn't do this with the stock alternator but started when I put on a DC Power unit.

 

[Chris2590]

When I first start mine the bolt gauge barely moves off the first line and then after about a minute or two it shoots up and if I have the heat/a/c running it starts blowing out a lot more air. It's always done it so I've always thought it was normal.

 

[79jasper]

That is normal. That's the glowplugs turning off.

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[Chris2590]

Ok awesome thanks I learn something everyday.