Edmunds Answers



  • zaken 11/24/13 2:37 am PST

    Please make sure all of the following things are in place:

    1> There must be a black ground wire from an engine bolt to a bolt in the firewall. If that wire is missing; you need to make another one and connect it. It should be made from 12 gauge stranded electrical wire; with the insulation stripped from both ends and a ring terminal crimped to each end.

    2> There also should be another ground wire from the battery ground cable clamp to a bolt in the fender or body nearby. This extra ground cable must be added if it is not already there.

    3> The main battery ground cable should go to a bolt that threads directly into the engine. It should not go to a bracket, nor to a painted object. It must not connect to a plastic or non metal part.

    4> The alternator output cable that is red with a black stripe connects to a fusible link which is a different color (probably green). The fusible link goes to the terminal on the starter solenoid where the red positive battery cable also attaches.

    Once these changes are made; the test light probably will read bright. Do not worry about or try to test the ECU. It probably is good.

  • jonathan7eve 11/24/13 10:52 am PST

    Thank U! I will check all that today, and I'll get back to U!! :):) thank U so much!!:):)

  • jonathan7eve 11/24/13 6:08 pm PST

    It still don't charge!, the grounds are connected! I check continuity from the engine to the chasy an the battery to the engine en battery! It is have a fuse for the alt? Where is it!?

  • thecardoc3 11/24/13 6:52 pm PST

    There are three connections to your alternator, the main output which is obvious and the other two are the "L" terminal and the "F" terminal. Those two connections go directly to the internal regulator inside the alternator, the other end of them go to the PCM, beacuse this is a full PCM controlled charging system. the "L" terminal (orange wire) is the one you need to be concerned with for the moment. Unplug the connector from the regulator, and attach a jumper wire to that pin. take a test light connect it to the battery positive terminal and touch that jumper, the lamp should light up just like a bulb would in the dash if the alternator controlled it directly. Now start the engine and repeat, if the alternator is good it will start charging. The 12v signal to turn the alternator on comes from the PCM, there are conditions that can result in the PCM commanding the alternator to turn off, which would have that orange wire grounded by the PCM. You will need service information and a full scan tool to proceed beyond this point.

  • zaken 11/24/13 10:00 pm PST

    The information that cardoc3 gave you is good. Check for voltage at the alternator plug when that plug is disconnected as he recommended. If the test light lights up; then insert the plug back into the alternator, and start the engine. If the alternator does not charge; it is likely that the alternator diodes were previously damaged when you ran the motor with the alternator output cable disconnected. In that case; the alternator will have to be replaced.

    If you decide to buy a remanufactured alternator; please be aware that most alternators sold by discount parts stores are repaired in Mexico by people who do not have all the necessary parts; and also do not have proper test equipment. These alternator have a very poor reliability record. The way to tell a properly remanufactured and thoroughly tested alternator is that it comes with a computer printed test report in the box. If a store tries to sell you an alternator that does not come with a test report; it is not a good quality part (regardless of the length of the warranty). Napa Auto Parts stores sell professionally remanufactured, thoroughly tested alternators. Some other parts stores also sell alternators that come with test reports; but that varies with the region of the country.

  • jonathan7eve 11/25/13 10:47 pm PST

    Hi guys, it still don't charge!:(:( I have check , double check everything!! Before I change the engine the car had this problem, I have test the alt 2 times! I charge the battery and it go down till it die! I put an other jumper from the alt to the starter, and it still don't work!:(:( I don't know what to do!!:( the signal for the alt is weak , has 5V but doesn't activate the alt!!

  • zaken 11/26/13 12:09 am PST

    There are different ways to test an alternator. Most of those tests only look for voltage; but do not measure how much current the alternator produces. The alternator has 3 different coils in it; which each produce power during 1/3 of a revolution of the pulley. In order for the alternator to work properly; all 3 of these coils need to be operating. Each of those coils is connected to a pair of diodes; which only allow current to flow in the desired direction. But these diodes can be easily damaged; if the alternator is run when the output cable is not connected to the battery. Once the diodes are damaged; the alternator may still produce power; but it will not be produced during the entire revolution of the pulley. A voltmeter cannot detect this; because the display cannot change fast enough to track each of those 3 sections. So even though it generates voltage; it will act like the alternator is not producing enough power.

    The only kind of tests which can detect this type of problem are either an ammeter which mesaures the peak current output; or an oscilloscope which displays the output wave shape. Most parts stores do not have the equipment needed to do these tests; so they just test the alternator with a voltmeter, see some voltage; and incorrectly tell you that it is good.

    If you cannot find an aiuto electrical specialist or alternator remanufacturer in your city who has the needed equipment to test for open diodes; then the next best thing to do is to assume it is bad; and replace it with a known good alternator. PLEASE do not buy an alternator unless it comes with a computer printed test report in the box. Alternators which do not come with this report are all too likely to not have been thoroughly tested.; and you may end up with another alternator that has the same problem. NAPA Auto Parts Stores sell alternators which are properly remanufactured; and they come with a printout of that alternator's performance. There also may be other stores in your town which sell alternators which come with a printed test report; but I can't tell you whether or where those stores are. Thank you for your cooperation and trust.

  • cjinohio03 11/26/13 4:41 pm PST

    I am going through the same thing with the same car model etc. What kind of alternator are you using? Is it a oem? Is the pcm sending a signal to it also?

  • cjinohio03 11/26/13 4:42 pm PST

    I forgot check my thread about my problems below:


  • thecardoc3 11/27/13 7:12 am PST

    Hi Chris.

    If you go up the page you will see where I explained that the F and L terminals of the alternator go to the regulator and to test the alternator all by itself, unplug the regulator, and put a jumper wire onto the "L" terminal for access to it. Then start the engine and take a 12v test light and connect it to battery power, and then touch that jumper wire. That will provide the turn on power to the alternator and if it is good it will charge. The reason this test is important is you need to seperate the alternator from the computer controlled side of things. The computer can command the alternator to not charge by grounding the L terminal.

    One of the questions you asked in that other forum about it having a replacement PCM in it already, no it could not have been programmed incorrectly, but that doesn't mean the PCM itself is working correctly or whether or not there is a wiring harness issue at play. I would need to do the testing myself before I can really say one way or the other what is going on, but I'm leaning towards the problem being on the car and not with all of the "bad" alternators.

  • jonathan7eve 11/28/13 12:07 pm PST

    Hi! Thank you for all your response! finally the car worked! I put a new regulator to the old alt an now works fine!

  • cjinohio03 11/29/13 12:31 pm PST

    That's great where did you get just a regulator at?

  • stressedout101 04/22/16 6:05 pm PST

    I'm having the same problem my autozone manager here ordered3 altinators all tested good but nothing on the out put side on the car I'm beyond confused I have gone over this motor 3 or 4 times and checked all the grounds fuses relays and wiring


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