How JustAnswer Works:

  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.

Ask Randall C Your Own Question

Randall C
Randall C, ASE Master Tech
Category: Cadillac
Satisfied Customers: 11129
Experience:  ASE Master Tech, 32 years exp,Cadillac 6 yrs
Type Your Cadillac Question Here...
Randall C is online now
A new question is answered every 9 seconds

Have a 1994 Cadillac Deville 4.9. Alternator will not charge battery.

Customer Question

Have a 1994 Cadillac Deville 4.9. Alternator will not charge battery.Had it tested twice off car and is OK. Battery is about a year old when charged starts car OK. Charged it up overnight and showed on digital meter 12.35v. Start car and volts across terminals was 11.98v and increasing RPM, volts went down to 11.78.Idiot light does not light with engine key to on or when car is running. Alternator connection has an S wire(larger red wire)and L wire (smaller red wire)These wires had been spliced when new alternator was put on 2 years ago so checked voltage at S wire engine off showed same as Battery volts. L wire showed .025v. Engine running, S wire at splice was 11.48v and L wire was 10.78v.Could the lack of idiot light showing up means alternator is not sensing that it is time to keep battery charged and take care of other voltage needs on engine?
Submitted: 4 years ago.
Category: Cadillac
Expert:  Randall C replied 4 years ago.

Hello, I can not say if you have a wiring problem between alternator and light but will confirm 100% that the light has to work for th alternator to kick in and charge. the light is part of the "power" styetem to the internal regulatr to activate "volt sense". I pu the diagram below and you will see the bulb in the circuit and the volt sense at alternator. A burned out bulb can allow the alternator not to work.

 

 

graphic

Randall C, ASE Master Tech
Category: Cadillac
Satisfied Customers: 11129
Experience: ASE Master Tech, 32 years exp,Cadillac 6 yrs
Randall C and 6 other Cadillac Specialists are ready to help you
Customer: replied 4 years ago.
Thanks for your reply. Is the idiot light something that is easy to replace or is it hard to get to and involves a lot of expertise to get at it? I live in near Atlanta and there is a car electric repair place I could contact about repacing the bulb but is 32 miles from me so if this is quite a project for one to do, would I be able to make it there on a fully charged battery ot woud I need to take along another battery as a back up?
Customer: replied 4 years ago.
Would have appreaciated to know if I could change the bulb myself/ Guess that was another question and the part about doing everything to get you help on your problem is not exactly true
Expert:  Randall C replied 4 years ago.

Sorry, If a question is a 2-3 part qestion about same problem, we all usually help the customer. in your case, it got late and i logged off last night and did not see your reply till this AM. If i rememebr correctly, you can get to the bulb after the top of dash is off. Pulling the top off is one step to pull the cluster out to get to bulb. Directions are below. You may get top off only and reach to bulb from behind cluster, if not, you will have to pull the cluster out which after top is off, there are 4 screws. There just is not more info to send as far as pics etc due to gae of car. this is the best i have onhand

 

graphic

  1. Disconnect battery ground cable.
  2. Pull fuses A-5-IPC and B5-IPC from rear compartment fuse panel, pull fuse A3-IGN1 from engine compartment fuse panel.
  3. Using a small flat bladed screwdriver, pry defroster grill upward off of instrument panel upper trim panel, Fig. 17.
  4. Remove sunload and headlamp auto control sensors from defroster grill.
  5. Remove three upper trim panel attaching screws through defroster grill opening.
  6. Remove heat and A/C vents from front of instrument panel.
  7. Remove four upper trim panel attaching screws through vent openings.
  8. Remove upper trim panel from instrument panel.
  9. Disconnect electrical connectors from top of instrument cluster.
  10. Remove four instrument cluster retaining screws.
  11. Raise instrument cluster, then remove two PRNDL mechanism attaching screws.
  12. Reverse procedure to install.
Randall C, ASE Master Tech
Category: Cadillac
Satisfied Customers: 11129
Experience: ASE Master Tech, 32 years exp,Cadillac 6 yrs
Randall C and 6 other Cadillac Specialists are ready to help you
Customer: replied 4 years ago.

Thanks for getting back to me and sending the schematics on changing the idiot light. Getting at the light is quite involved so I have had the car towed to a Auto electric repair shop to have the kuight fixed so the alternator will charge again, I have an issue with too fast of an idle and will get back to you another time to see what suggestions you have for that problem.

Thanks for your help

JustAnswer in the News:

 
 
 
Ask-a-doc Web sites: If you've got a quick question, you can try to get an answer from sites that say they have various specialists on hand to give quick answers... Justanswer.com.
JustAnswer.com...has seen a spike since October in legal questions from readers about layoffs, unemployment and severance.
Web sites like justanswer.com/legal
...leave nothing to chance.
Traffic on JustAnswer rose 14 percent...and had nearly 400,000 page views in 30 days...inquiries related to stress, high blood pressure, drinking and heart pain jumped 33 percent.
Tory Johnson, GMA Workplace Contributor, discusses work-from-home jobs, such as JustAnswer in which verified Experts answer people’s questions.
I will tell you that...the things you have to go through to be an Expert are quite rigorous.
 
 
 

What Customers are Saying:

 
 
 
  • Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help. Mary C. Freshfield, Liverpool, UK
< Last | Next >
  • Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help. Mary C. Freshfield, Liverpool, UK
  • This expert is wonderful. They truly know what they are talking about, and they actually care about you. They really helped put my nerves at ease. Thank you so much!!!! Alex Los Angeles, CA
  • Thank you for all your help. It is nice to know that this service is here for people like myself, who need answers fast and are not sure who to consult. GP Hesperia, CA
  • I couldn't be more satisfied! This is the site I will always come to when I need a second opinion. Justin Kernersville, NC
  • Just let me say that this encounter has been entirely professional and most helpful. I liked that I could ask additional questions and get answered in a very short turn around. Esther Woodstock, NY
  • Thank you so much for taking your time and knowledge to support my concerns. Not only did you answer my questions, you even took it a step further with replying with more pertinent information I needed to know. Robin Elkton, Maryland
  • He answered my question promptly and gave me accurate, detailed information. If all of your experts are half as good, you have a great thing going here. Diane Dallas, TX
 
 
 

Meet The Experts:

 
 
 
  • Dave Nova

    Cadillac Technician

    Satisfied Customers:

    1469
    ASE Master Certification. GM World Class Certification
< Last | Next >
  • http://ww2.justanswer.com/uploads/DT/dt69nova/2012-6-15_234154_pic1.64x64.jpg Dave Nova's Avatar

    Dave Nova

    Cadillac Technician

    Satisfied Customers:

    1469
    ASE Master Certification. GM World Class Certification
  • http://ww2.justanswer.com/uploads/JF/JFN1/2011-2-26_33039_180754101501129867381533152761315265045893127711n.64x64.jpg Jerry Newton's Avatar

    Jerry Newton

    Cadillac Technician

    Satisfied Customers:

    1181
    ASE Master Technician, L1, Master GM Technician. Over 20 years of bumper to bumper GM experience.
  • http://ww2.justanswer.com/uploads/PE/peterpete190/2012-2-24_1274_20120215135406.64x64.jpg Pete's Avatar

    Pete

    Cadillac Technician

    Satisfied Customers:

    1133
    15 years Cadillac experience as a technician.
  • http://ww2.justanswer.com/uploads/testedtuff/2009-09-26_170108_pictures.jpg John's Avatar

    John

    ASE Certified Technician

    Satisfied Customers:

    941
    ASE CERTIFICATIONS A1-A8 & L1 / 40 YEARS AUTOMOTIVE EXPERIENCE
  • http://ww2.justanswer.com/uploads/joecamel90/2008-11-13_03615_head_shot.jpg George H.'s Avatar

    George H.

    ASE Certified Technician

    Satisfied Customers:

    595
    ASE Master Tech 15+ Years
  • http://ww2.justanswer.com/uploads/MO/molurch/2012-6-6_214526_500.64x64.png Don 'Mo Lurch''s Avatar

    Don 'Mo Lurch'

    Cadillac Technician

    Satisfied Customers:

    462
    GM, Cadillac Cert., Heavy Line Mech, Race Shop Owner, Mobile Electronics.
  • http://ww2.justanswer.com/uploads/tsmodie/2009-6-10_144056_tim.jpg Tim Mohr's Avatar

    Tim Mohr

    ASE MASTER TECH

    Satisfied Customers:

    385
    30 YRS EXPERIENCE, FOREIGN AND DOMESTIC, GAS AND DEISEL