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.

if the alternator was properly checked , the rectifier would have shown a problem
just putting a multimeter on the battery is not checking
the alternator has to be removed and bench tested where the voltage regulator is tested ( if internal) , the maximum current is checked and the voltage is ac or dc indicating rectifier pack
it is then refitted and the voltage regulator if external is checked and if the voltage is in the ECM that is also checked

05 Dodge Caravan No Start P0688 bad wire - YouTube

? 10:49
www.youtube.com/watch?v=yshodC_crqo
Sep 22, 2012 - Uploaded by Brian Mann 2005 dodge caravan crank no start p0688 asd relay circuit ... butdoing the voltage drop on the back of the connector to the ipm to.... ECM PCM STARTER 2003 DODGE GRAND CARAVAN 3.3L V6 WONT START ... 1996, 97, 98 Dodge Caravan Starter install3.8L V6 - Duration: 8:39. by Gary O 4,364 views.

The voltage regulator is inside the PCM.

The pcm contains the voltage regualtor,have you checked the charging voltage?If it is overcharging most likely is bad pcm.

If the noid light is working, the pcm is good. Why do you say it burned out? I would check ac voltage at each injector with engine running. If #2 has lower voltage than the others, you probably have a bad wire or connector.

The voltage regulator is in the PCM. If there is a problem with it, the PCM has to be replaced.

Sometimes that code is generated when the charging voltage from the charging circuit is too low and the minimum airflow spec gets lost by the pcm. This can be a bad alternator, battery etc. As well if someone has adjusted the set screw in the throttle body trying to fix the code then I'd suggest retesting with a used throttle body. As well one last thing the intake gaskets/plenum pan on those engines blow out and cause a vaccum leak that can cause spark knock and oil consumption. If that vaccum leak was large enough it could cause your low vaccum reading and that code. As always check the accuracy of the map sensor and tps when dealing with idle speed issues

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.

A code 42 is the Auto Shutdown Relay Control Circuit....The ASD relay is located under the hood in the Power Distribution Center next to the battery. Change the ASD relay, that should fix you up. If that doesn't work...you might have to check the PCM. But replacing the ASD relay should do it.

Bryon

Will it give you codes on the dash if you turn the key on and off 3 times.