Crazy4cruz Posted October 3, 2013 Share Posted October 3, 2013 I was driving home this evening and noticed the "AMP" light coming on while I was driving. The light only appears to come on when I do something such as stepping on the brake peddle, or activating the turn signal. When I am just driving at regular speed no light. I checked my service manual it said it could be one of three things. Lose or missing belt, defective field relay, or a defective generator. Car electrical is my Achilles heel so I'm hoping someone might be able to offer some help here. Both belts seem to be taught so I'm assuming that's not it. My manual talks me through checking the voltage but to be honest it is all Greek to me. Something about above 5 volts the relay is bad, below 5 volts and its probably the generator. Am I supposed to be running this check with the engine running? Engine off? Ignition on? Help please. Link to comment Share on other sites More sharing options...
1965rivgs Posted October 3, 2013 Share Posted October 3, 2013 Test are to be done with the engine running....but a shop will not use the troubleshooting procedure in the manual, too much time and bother checking/adjusting an old mechanical voltage regulator. What a shop will do is "full field" the alternator while monitoring the alt output. If the alt performs properly they will replace the regulator. If not, they`ll probably change both just to prevent a comeback and a dissatisfied customer. Sounds to me like you should find a local shop that services older vehicles. This is a plus because the stock charging system is quite different than a typical later model system. How old is your battery? If it is over 4 years old consider replacing it to save some money at the shop, good luck, Tom Mooney Link to comment Share on other sites More sharing options...
Crazy4cruz Posted October 3, 2013 Author Share Posted October 3, 2013 Tom, thanks for the information. The battery is relatively new. If ultimately my mechanic is going to end up replacing the regulator and/or alternator, couldn't I save myself the time and replace both myself? I can certainly manage the replacements was just dumbfounded by the testing instructions and volt meters and the like. For the cost of my mechanics time to troubleshoot the issue I could just buy a new alternator and new regulator, yes? Link to comment Share on other sites More sharing options...
Guest slacker1965 Posted October 4, 2013 Share Posted October 4, 2013 Tom, thanks for the information. The battery is relatively new. If ultimately my mechanic is going to end up replacing the regulator and/or alternator, couldn't I save myself the time and replace both myself? I can certainly manage the replacements was just dumbfounded by the testing instructions and volt meters and the like. For the cost of my mechanics time to troubleshoot the issue I could just buy a new alternator and new regulator, yes?if shop rates in your area are anything like here in clt(95/hr) you could remove your alt yourself & have it tested, replace it(if bad) & your voltage regulator, for close to what a shop would charge for one hour. kinda a pita to get to if your car has a/c. in my area, autozone, oreiley's etc test them for free. I take my stuff to a auto elec shop. I assume that you know to disconnect the neg batt term 1st.the only problem with throwing parts at an issue is that you sometimes fix the symptom, not the problem. is this a new issue? has the car sat for a long period of time? I think that the external regulators on these cars are mechanical, not solid state electronic like modern internal alts have.good luck, let us know how you make out Link to comment Share on other sites More sharing options...
Crazy4cruz Posted October 4, 2013 Author Share Posted October 4, 2013 Kevin,Yes this is a brand new issue. Have never had any electrical issue with my Riviera. And no, the car has not sat. I drive it at least once or twice a week either to work or on the weekends. And in fact have been driving it more often the last few weeks back and forth to my mother in laws house to help care for her. I do know a very good, very trustworthy mechanic but he does charge $95 an hour. I looked on my local AutoZone website and can get both parts for less than the $95 he would charge me just to diagnose the issue. You touched on my larger concern though. I can certainly replace both parts, but if I replace both (just to be safe) and the amp light still comes on, I still haven't fixed the problem? I can do the mechanical replacements, that's easy. But if it doesn't correct the issue I still don't know how to diagnose or trace down the underlying issue. Link to comment Share on other sites More sharing options...
Mr Riviera Posted October 4, 2013 Share Posted October 4, 2013 It could be that the belts are tight but glazed . This will cause an issue as well . If you replace the parts buy both , then install one and then the other . Your first choice may solve the problem and you can return the other part ? Link to comment Share on other sites More sharing options...
RivNut Posted October 4, 2013 Share Posted October 4, 2013 When you're replacing belts, it used to be that you would asked for a matched pair of belts for the a/c - alternator belts. They were matched exactly in length so that when you tightened them, one would not be looser than the other. The reason for running two belts on the a/c - alternator is that not much of the diameter of either pulley is touched by the belt. One belt would probably slip given so little area for contact. Two belts ensures that enouch contact is made so there's no slippage. If both belts are not exactly the same length, you get the effect of running only one belt. Make sure that if you change one, you change both at the same time. The power steering belt makes contact with much more of the diameter of the p/s pulley so there's only need for one belt.Ed Link to comment Share on other sites More sharing options...
Crazy4cruz Posted October 4, 2013 Author Share Posted October 4, 2013 Belts are only a few weeks old and are both the same size. Is there any advantage to replacing regulator or alternator first, other than the fact that the regulator is half the cost of the alternator? Link to comment Share on other sites More sharing options...
Mr Riviera Posted October 4, 2013 Share Posted October 4, 2013 The regulator is easier to change !i Link to comment Share on other sites More sharing options...
1965rivgs Posted October 4, 2013 Share Posted October 4, 2013 Tom, thanks for the information. The battery is relatively new. If ultimately my mechanic is going to end up replacing the regulator and/or alternator, couldn't I save myself the time and replace both myself? I can certainly manage the replacements was just dumbfounded by the testing instructions and volt meters and the like. For the cost of my mechanics time to troubleshoot the issue I could just buy a new alternator and new regulator, yes?I`m assuming the problem is isolated to the charging system components. It could very well be you have a wiring or connection problem at the reg or alt...or even a seemingly unrelated wiring problem elsewhere. Your car is 50 years old, anything is possible. You are paying the mechanic diagnostic time for diagnosis. Without same, he would just be replacing parts. Good luck, Tom Link to comment Share on other sites More sharing options...
Crazy4cruz Posted October 6, 2013 Author Share Posted October 6, 2013 So ... just like my 50 year old car ... went out Friday to replace the regulator and alternator ... started up the car and no "amp" light issues. Ran the engine, drove it around, went to my mom in laws house and the "amp" light has not come one once. Needless to say I'm holding on to the new alternator and regulator I just purchased. Link to comment Share on other sites More sharing options...
Bill Stoneberg Posted October 7, 2013 Share Posted October 7, 2013 O'Riellys has a meter where they can test the regualtor and tell you the output of the Alternator without having to remove anything from the car. I have used it before and it works well. Link to comment Share on other sites More sharing options...
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