Engine/Transmission (1998.5 - 2002) altenator troubles...

[SeanM]

Ok, so I think my altenator went bad. I was driving to lunch and the check guages light came on and my volt guage was at 8. When I was checking everything I found I had no voltage at my field terminal wires. When I checked them I had the engine off, key switch on and the grid heater was off. Does the engine have to be running to have voltage at the wires? Or do I have another possible culprit here?

 

[jhoughton]

Check the 140 amp fuse located in the fuse box in the engine compartment. Blew mine when changing the Alt without unhooking batteries. Cost about $9. 00 at the dealer. Did not try an autopart store, they may have them as well. The hot wire at the Alt will have battery voltage when the engine is off.

 

[SeanM]

I think you may have misunderstood. I am talking about the field wires on the back of the alt that provide power to the windings so the alt will start to produce power.

 

[DavidC]

I would think the engine needs to be running and the PCM would see that and allow the alternator to work. Check it with the engine running.



Dave

 

[Weatherman1964]

I had same issue, volt meter on dash went to 8 and the check gauges light came on. When engine was not running, gauge reads battery voltage, when engine is running it appears to be reading alternator output. Mine has 125k miles on it and upon further inspection I could see that my top alternator bolt had been loose for quite some time and had elongated the top hole in the housing. So I replaced the alternator without hesitation and all is well now. I had a coolant leak at exactly the same time and found the water pump was bad, got lucky on this one! Changed them both out in about 30 minutes, very simple job. Watch that the new alternator has the + terminal in the same spot, my new one has the + connector on the bottom instead of the back. I had to pull the wire real tight and zip tie a piece of inner tube between the wire and the alternator housing.

 

[SeanM]

I ended up rebuilding my altenator. One of the wires going to my brushes broke. I would have put up pics but I didn't have time. In the ended it cost me 2 hours, some brake clean, and $38. 74 for the brushes and bearings. It now puts out 14. 1 volts.



To answer my original question yes the engine has to be running to have power at the field wires.

 

[DavidC]

Thanks for the update, glad your fixed and at a reasonable price.



Dave