Question about Suzuki Cars & Trucks

1 Answer

Bad diodes: Replace them or the alternator

I was told I had bad diodes in my alternator. Should I replace the whole alternator or replace the bad diodes?

Posted by on


1 Answer

  • Level 3:

    An expert who has achieved level 3 by getting 1000 points


    An expert that got 20 achievements.


    An expert that got 10 achievements.


    An expert that got 5 achievements.

  • Suzuki Master
  • 20,706 Answers

Told, and what tests did they do , in order to say, those magic words.
(max amps tests under max load (tools) or a scope test.
if they didnt do those to tests, they are just Guessing.
if you want to guess. why not do that yourself, after all its your wasted cash , not his... see?
IMO, youll never ever get the diodes out and back in , and not mess it all up. (some are easy , most are hard.)

if on the other and all all this post really is , is the failure to state
the symptoms, and then asking how to do the tests. then we can do that.
let me guess, (i roll the dice) and land on.
Battery will not charge, driving, and voltage is not 13.3v to 15v driving.
so the battery discharges, and the soon the engine stalls.
did i guess right?

Posted on Nov 20, 2013


3 Suggested Answers

  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

Hi there,
Save hours of searching online or wasting money on unnecessary repairs by talking to a 6YA Expert who can help you resolve this issue over the phone in a minute or two.

Best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.

Here's a link to this great service

Good luck!

Posted on Jan 02, 2017

  • 6784 Answers


Removing the Old Alternator Step1 Pull your Mazda into the garage or your work area. Turn the car off and let it sit for a while to cool. Step2 Begin by disconnecting the negative cable of the battery. Step3 Remove the serpentine belt from the pulley on the alternator. Do this by using a socket wrench to turn the serpentine automatic belt tensioner so that it allows slack in the belt. Then simply slip the belt off the alternator pulley. Step4 Locate and disconnect all the mounting bolts on the alternator, use a vehicle specific manual if you have any trouble. Step5 Disconnect all wires attached to the alternator then remove the alternator from the Mazda. Installing the New Alternator Step1 Slide the new alternator into place. Do not worry about the serpentine belt yet. Step2 Replace the bolts that held the previous alternator to secure the new one in place. Step3 Attach the wires to the new alternator the same way they were attached to the old one. Step4 Adjust the serpentine belt tensioner the same direction you did in Section One to put slack in the belt. Wrap the belt around the pulley of the new alternator and then remove the socket wrench from the automatic belt tensioner. Step5 Inspect the belt to be sure it is not snug and follows the path required in the pulley and belt configuration diagram. Step6 Hook the negative battery wire back to the negative terminal on the battery.

Posted on Mar 21, 2009

michigan man
  • 3533 Answers

SOURCE: A/C compressor bearing sounds bad. Can bearing & pulley be replac

it is best to replace the whole compressor but if it was me I would go and get a can of 134A oil and put that in first to see that helps with the problem and if not then replace the compressor they are somewhere around $40 to $75 at a good salvage yard and you can try and if you cannot find one there try or call them at 1-800-292-1032

Posted on Mar 22, 2009

Add Your Answer

Uploading: 0%


Complete. Click "Add" to insert your video. Add



Related Questions:

1 Answer

2008 pathfinder goes well turn the motor of makes a grind/wherr noise told it is the altinator pulley how do i fix this

Replace the alternator. When the pulley shaft makes noise, the sealed bearing has failed. You cannot or would not take it apart to replace the bearing. You just replace the whole alternator.
To be certain, take off the belt and spin the pulley. If it makes noise or feels rough spinning, it is bad.

Jul 27, 2017 | Cars & Trucks

2 Answers

I am getting a code telling me my voltage regulator diodes are bad on my 1996 Dodge Grand Caravan. Should I be replacing the PCM to fix the problem.

Not sure about the 96 but, voltage regulators generally have to do with the alternator. As a matter of a fact you can just replace the voltage regulator on the alternator as opposed to spending the money that it cost to replace the whole alternator, I found this out because a mechanic ripped me off and charged me for a alternator but, he only replaced the voltage regulator diode part on the alternator.. Replacing the PCM is going to be expensive and in my opinion not necessary

Feb 09, 2017 | Dodge Grand Caravan Cars & Trucks

3 Answers

Do I have a bad alternator?

Do you hear any squealing when you drive the car? If so the belt is slipping so yes. Replace it anyway because you don't want it to snap and Replace the battery. Retest the charging voltage you are looking for 12.7v to 13.9 if you don't have a multi meter take it to another garage and ask nicely if they could check the charging voltage most will not charge but you want the voltage NOT pass/ fail or its fine
I recommend this as some battery faults can give faulse charging readings

Jul 13, 2017 | 2005 Dodge Neon SXT

1 Answer

Something is drawing my power when my car is off and I have replaced my battery 2 times in a week and a half I was told my alernator is ok what else could it be?

Your alternator may not be ok. It is common for an alternator to continue to work and charge even with a shorted diode. However, it will allow the battery to drain when the car is shut off. Also make sure that all the interior lights including any mirror lights are turned off. Try turning them right off, even though they are supposed to turn off when you close the doors, trunk, etc. If you have a meter, you can check your alternator easily enough. You need to disconnect the battery - take the negative cable off. Then disconnect the battery cable from your alternator and check the terminal with an ohm meter. There should be no continuity to ground through the alternator in one direction. If you have continuity to ground in both directions through the alternator, you have a bad diode and have found your problem. Repair or replace the alternator.

Feb 18, 2011 | 2006 Pontiac G6

1 Answer

Battery light, charge/discharge, comes on and stays on. Had the alternator checked and installed a new battery.

There is a diode inside the alternator that controls the charge light. It is possible for this diode to go bad even thought the alternator is charging like it is supposed to. Only way to really tell is to replace alternator.
Hope this helps

Aug 26, 2010 | 1998 Mercury Grand Marquis

1 Answer

2000 nisaan sentra, battery light and brake light pops on periodically, took it to dealership, they said all the reading was good on the battery and alternator, they just to change the battery cables did...

its a bad alternator, a bad diode, replace the alternator this will solve your problem, when these alternators go bad the dash lights come on,it sounds like it sometimes charges and other times not,the car was charging when they got it so they really couldnt find much,ive run into this alot, check the connection at the alternator and battery if connections are good then replace the alternator, good luck.

Mar 31, 2010 | 2000 Nissan Sentra

1 Answer

1993 dodge caravan, over charging, replace the alternator, was tested and told it was bad, still over charging. Was told that the computer controls the voltage output, do I replace the computer system now,...

The computer has NOTHING to do with the alternator output.
The alternator is self regulating, with diodes, and rectifiers.
If the alternator is over charging it is because your battery is not accepting the charge, so the charger works harder and produces more to charge it, up to a point.
Was the alternator that you installed new or rebuilt ?
It could be another bad alternator.
Please let me know.

Feb 11, 2010 | 1993 Dodge Caravan

1 Answer

2001 Dodge Grand Caravan battery light is on. Battery and alternator have been checked and are ok. What could be wrong?

The alternator has a bad diode in the diode bridge in the alternator,this turns the light on,even though the alternator checks good,and is charging correctly,there is a bad diode,this diode ,along with others,changes ac voltage to dc voltage,if not replaced,it will start causing components to go out.

Feb 08, 2010 | 2001 Dodge Grand Caravan

2 Answers

The generator light on my 76 cadillac deville comes on but slowly dims out when driving

sounds like alternator needs replacing, could have bad diodes,or regulator is going bad,

Oct 30, 2009 | 1976 Cadillac Deville

1 Answer

My battery and brake light started coming on together. mostly in neutral. dims in 3rd and around corners.

Sounds like bad diodes in the alternator. Have a charging system test done on your truck. If your alternator has bad diodes, it will show up on most charging system analyzers. If this is the case, you will have to replace your alternator.

Oct 17, 2009 | 1989 Toyota Pickup SR5

Not finding what you are looking for?
Cars & Trucks Logo

Related Topics:

58 people viewed this question

Ask a Question

Usually answered in minutes!

Top Suzuki Experts


Level 3 Expert

80637 Answers

Colin Stickland
Colin Stickland

Level 3 Expert

22326 Answers

Jeffrey Turcotte
Jeffrey Turcotte

Level 3 Expert

8841 Answers

Are you a Suzuki Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides