Batt Light at Higher RPM
Thread Starter
|
Junior Member
Joined: Nov 2002
Posts: 3
Likes: 0
From: Wisconsin
Batt Light at Higher RPM
Hi Guys,
Love this site!
I have a '97 Lariot SC LB 4X4, 5.4. This morning when warming up the truck, and the heater fan on full, just before I took off, I revved it up a little. I thought I heard the fan slow way down, and then go full again. I did it again, same thing, and also the BAT Light came on. As it returned to lower RPM, the Bat Light went out.
As I was driving it, I noticed that whenever it revved over about 3500, the light came on, and the Volt gauge dipped a little. Under that RPM, no light, and the Volt gauge is normal(15V?).
I am thinking alternator, but I have never seen this before. Any ideas? Thanks.
Well, I guess I should have done a more thorough search. I found a couple posts with the exact same symptoms. Best I got out of the is the brushes in the alternator are weak. I will try to replace the brushes, if not a new alternator. Probably will do the belt right away, too. 113K on it. Think it's time?
Love this site!
I have a '97 Lariot SC LB 4X4, 5.4. This morning when warming up the truck, and the heater fan on full, just before I took off, I revved it up a little. I thought I heard the fan slow way down, and then go full again. I did it again, same thing, and also the BAT Light came on. As it returned to lower RPM, the Bat Light went out.
As I was driving it, I noticed that whenever it revved over about 3500, the light came on, and the Volt gauge dipped a little. Under that RPM, no light, and the Volt gauge is normal(15V?).
I am thinking alternator, but I have never seen this before. Any ideas? Thanks.
Well, I guess I should have done a more thorough search. I found a couple posts with the exact same symptoms. Best I got out of the is the brushes in the alternator are weak. I will try to replace the brushes, if not a new alternator. Probably will do the belt right away, too. 113K on it. Think it's time?
Last edited by WI_Shep; Mar 5, 2003 at 07:27 PM.
Senior Member
Joined: Jan 2003
Posts: 379
Likes: 0
From: Cincy OH
I am thinking the same thing not sure about the 97's but on early models like 92's if the voltage goes above 15volts the radio,blower motor and other things would cut off i would take a volt meter to the batt rev the motor and see what it reads i would bet it is about 15v.
John
John
Thread Starter
|
Junior Member
Joined: Nov 2002
Posts: 3
Likes: 0
From: Wisconsin
All fixed. Took it in to a reputable shop, and they tested the battery and the alternator. Alternator was going, the brushes were chewing up the commutator. Battery checked good! Replaced alternator and belt for $300, including labor. Alternator was 130 Amp, $200.
