 |
 | Home | Contact Us | FAQ | Search & Site Map | Link to Us |
 | Sign In | Join | Other 45 Sites in Network |
Car Forum / Ford / Ford Cars / March 2006Battery Voltage drop at higer revs - 99 Taurus
I have a 99 Taurus with the 3.0 engine. Today on a long trip I noticed that the battery 'idiot light' came on under hard acceleration. Upon further investigation with a OBDII tool while driving the vehicle I see that the battery voltage drops from a steady 13.5V to around 12v only when the engine revs are increased to around 4,000 or more. The idiot light comes on at these times. This is indicative of failure of something in the charging system. Does a knowledgeable mechanic here know if it is likely to be the voltage regulator or the alternator? I'm not even sure if the Taurus has a separate voltage regulator or if it's part of the alternator on this vehicle. Any advice welcome on diagnosing the faulty component. JP  SignatureJP White mailto:jpwhite3@bellsouth.net > I have a 99 Taurus with the 3.0 engine. > [quoted text clipped - 11 lines] > > Any advice welcome on diagnosing the faulty component. Brushes... really. They are probably available. Can usually happen between 125 and 190 kmiles It ALSO COULD be the VR, but that's classic of worn brushes. But IIRC the charging voltage SHOULD be about 14.3 to 14.6 SignatureYeh, I'm a Krusty old Geezer, putting up with my 'smartass' is the price you pay..DEAL with it! >> I have a 99 Taurus with the 3.0 engine. >> [quoted text clipped - 14 lines] > Brushes... really. They are probably available. Can usually happen > between 125 and 190 kmiles Hey thanks for your quick advice!! The car has 72K on it, low for the year, my wife does about 8k a year. Something always seems to 'go wrong' on these long trips. I suspect it's because I'm the driver on long trips and she simply doesn't notice the early warning signs. > It ALSO COULD be the VR, but that's classic of worn brushes. But IIRC the > charging voltage SHOULD be about 14.3 to 14.6 Oh OK. I'll get the charging voltage checked independently, the ODBII system may not be well calibrated after 7 years of operation. Will changing the brushes help the average charging voltage also? Changing brushes sounds cheaper than buying a new alternator, just a little more work. I'll check online as well as ask at an auto parts store. Thanks again. JP SignatureJP White mailto:jpwhite3@bellsouth.net >>> I have a 99 Taurus with the 3.0 engine. >>> [quoted text clipped - 35 lines] > > JP Sounds early for brushes... go to google and search for my alt refurb article. Also check autozone's site to see if your Alt is the externally/PCM regulated 'new improved' type. SignatureYeh, I'm a Krusty old Geezer, putting up with my 'smartass' is the price you pay..DEAL with it! >>>> I have a 99 Taurus with the 3.0 engine. >>>> [quoted text clipped - 40 lines] >Also check autozone's site to see if your Alt is the externally/PCM >regulated 'new improved' type. If the car just gets knocked around town as a "wife's car" 72000 miles can have the equivalent run time of a highway driven car with almost 200,000 on it - so I'd still say, most likely - like 90+%, brushes. >>> I have a 99 Taurus with the 3.0 engine. >>> [quoted text clipped - 34 lines] > > JP Before you buy anything, i would clean the battery cables at the battery. check every high current power cable for corrosion and connection torque. Check the large high current wire at the alternator for a good connection. How often does the car run at 4000 RPM +?. Bob > Before you buy anything, i would clean the battery cables at the > battery. check every high current power cable for corrosion and > connection torque. Check the large high current wire at the alternator > for a good connection. All checked good with Battery and cables. Exchange alternator fixed it up. Charges at a higher voltage now. > How often does the car run at 4000 RPM +?. Rarely. Just when passing and needing the kick down. Typically cruises at 2500-2700 on interstate. JP SignatureJP White mailto:jpwhite3@bellsouth.net >> Before you buy anything, i would clean the battery cables at the >> battery. check every high current power cable for corrosion and [quoted text clipped - 10 lines] > > JP I had the same problem with a 95' Escort. The charging light would come on when the engine speed went over 2000-rpm. Changing the alternator fixed it. > It ALSO COULD be the VR, but that's classic of worn brushes. But IIRC the > charging voltage SHOULD be about 14.3 to 14.6 Your memory is right. Now charging at 14.3 with exchange alternator. Glad I caught it early before it let my wife down one day. JP SignatureJP White mailto:jpwhite3@bellsouth.net >I have a 99 Taurus with the 3.0 engine. > [quoted text clipped - 9 lines] >separate voltage regulator or if it's part of the alternator on this >vehicle. Your brushes are worn out and/or sticking. >Any advice welcome on diagnosing the faulty component. > >JP > I have a 99 Taurus with the 3.0 engine. > [quoted text clipped - 13 lines] > > JP loose belt ... under high rpm the alternator fan speeds up creating more load maybe the belt is slipping ... otherwise its the brushes .. the slip rings on the stator are not round or the brushes are so worn there is not enough spring pressure and at the higher rpm the contact is not good enough |
Reply to this Message |
 Sign In
 Join
 My Latest Posts My Monitored Threads My Blog My Photo Gallery My Profile My Homepage Start New Thread Enable EMail Alerts Rate this Thread
|
©2008 Advenet LLC Privacy Policy - Terms of Use
This website includes both content owned or controlled by Advenet as well as content owned or controlled by third parties.