Engine/Transmission (1994 - 1998) Weird alternator woes

[CumminFast]

My truck is ******* me off. I had my alternator tested and batteries tested and they are both good. Then I thought the volt regulator went bad so I replaced my PCM and then I figured out all I did was blow my alternator fuse. Now it is acting up, but at least it is driveable. When I crank it up the battery charge gauge or whatever is always real low and the check gauges light comes on. Then when I get going it gets back up to 15. And sometimes when I let it idle it goes down to like 13 or so. Is something draining it? I have no idea. What do yall think?

 

[bmoeller]

Are all the battery connections clean? How about the connections to the starter or where the battery ground cables are connected to the truck? Is the ground O. K. at the PCM? Have you checked the voltage at the alternator when it is acting up to make sure the gauge isn't the problem? Hope this helps. LOL

 

[CumminFast]

Where is the ground to the PCM? Isn't it grounded when I bolted it up to the firewall?

 

[bmoeller]

I'm not 100% sure. Never had to mess with it yet.

 

[illflem]

Could be your battery temp sensor or it's wiring, under the driver's side battery on a '98, is messed up sending a signal to the PCM that the battery is too hot or cold to charge.

 

[CumminFast]

Do Advanced Auto alternators just suck or what? I got it diagnosted and they said mine wasn't putting out what it should so I took mine back and got another one and I just not getting amps when I crank it up. When I get driving they jump up though.

 

[bmoeller]

Got mine from Advanced Auto and so far so good. No problems so far in 10,000+ miles.



EDIT: oops, AutoZone, not AA.

 

[B.G. Smith]

Alternator

Are you sure the inlet air heaters are not what is causing the voltage to be low when you first start up? They will cycle on and off till the air is about 60 deg. or until you start driving and get above about 18 mph. bg

 

[Deezul1]

Rick

The only alternator problems I have had were quite a while ago with an overcharging problem from time to time and it turned out to be a bad battery cell and when the battery was replaced it went away. Unless it was something I dont remember and at my age thats very possible.

Good Luck

John

Your PM mailbox is full

 

[CumminFast]

I noticed tonight the headlights dim every 30 seconds. I mean not much you have to be paying attention. The same thing happens w/ the my cab lights and gauge lights.

 

[Deezul1]

Do they dim all the time every 30 seconds or just for 2-3 minutes after startup? If its just after startup then its grid heaters cycling. Does the Volt gauage show discharge down to 8 V or so? If its doing it all the time It might be grid heater relay is stuck closed, if so remove it and see what happens.

 

[BHaner]

Grid heater relay

I replaced my two relays on the fender to try to fix the same problem. The grid heaters continue to cycle after the motor is warm... . What controls the relays? The ECM? What temp sensor does it use?

 

[CumminFast]

My lights just dim about every 30 seconds even when I am warmed up, but the alternator doens't really fluctuate. It stays right around 14 or 15. When I start the truck it just takes forever to get up. I think these Advance Alternators just suck.