ECM not communicating with alternator's voltage regulator.


Asked by Mar 14, 2016 at 01:54 PM about the 1998 Dodge Grand Caravan

Question type: Maintenance & Repair

Battery is not charging.  Was told regulater bad.  Replaced alternator have same
problem. Suspected bad wire to ECM or ECM.

12 Answers


The ECM in some manner controls the voltage regulator, which charges the battery.

7 people found this helpful.

The voltage regulator works all on its own. The computer does not control it in any way.

3 people found this helpful.

rowefast is a MORON the voltage regulator driver is a chip built into the dodge PCM and can only be fixed by 3 methods 1 replace pcm 2 bypass internal pcm voltage regulator with an external one however this will have a check engine light on and a code and the battery guage will read zero 3 remove PCM and take it apart and replace or re solder the voltage regulator driver chip if issue is intermittent then re solder

20 people found this helpful.

Yes the charging system goes through the pcm ,The Electronic Voltage Regulator (EVR) is not a separate component. It is actually a voltage regulating circuit located within the Powertrain Control Module (PCM) . The EVR is not serviced separately If replacement is necessary the PCM must be replaced.check the wiring fron the alternator for a bad fusible link ,also check the wire from the alt to the pcm(brown/grey wire) ,here are some diagram for that system . The pcm would have to be flashed if someone has the equiptment then it can be flashed at somewhere else than a dealer but if you dont know anyone that has the tools to do this (good scanner -snap-on etc)with the reflash capability then it has to be done at the dealer...

18 people found this helpful.

Charging Diagram...

20 people found this helpful.

Plugin and pin location...

7 people found this helpful.

And the Chart...

13 people found this helpful.

My 2013 grand caravan battery light came on and my transmission wouldnt go anywhere. Itbkept reving up while acelerating and slowing down tob18 mph max speed. I had no throttle. I had 8 dash lights on as well. When I had the battery checked, it said voltage regulator failed. So I bought a new pcm from the dealer and installed it. Then i had to tow it to the dealer to have it flashed and programmed so it would start. After they flashed the new pcm it starts and runs now but the battery light is still on. We had it check at oriellys auto parts store, it still says the voltage regulator failed. Question, is the pcm bad or alternator? Is there a battery shutdown fuse? All wiring is good

8 people found this helpful.

Where can I find the chart for pins 21 to 40?


3 dead batteries in 4 months. Disconnect neg bat cable. Put circuit tester between bat and cable. Tested all fuses by removal. Light on circuit tester still on. Removed hot cable to alternator, tester light still on. Any help would be great. I will reserve my diagnosis until comments provide diag/options.

2 people found this helpful.

it would be better to use a meter with a amp and milli amp reading. the reading should be no more than 50 milli amps after the computer goes to sleep. You should wait at least three minutes for everything to shut down. if you still have a draw above that pull the big wire that feeds the fuse/relay center. If still a draw you will need to isolate main wiring branches. Pull wires from alternator etc..If drain goes away pull all the fuses including the maxi fuses. A wiring diagram would help.

1 people found this helpful.

Go to hardware/autoparts store, buy a plug like a trailer plug but with just two wires. It comes in a one piece you just cut in the middle, strip the wires, solder them to the alternator receptacle, take the other side of the plug and cut off the stock plug off the harness and solder on the other side of the new plug. Make sure you get the wires the right way around. Whether or not thats the problem right now can be in question but until you eliminate that shitty stock plug which can cause all sorts of weird problems, you wont know for sure and you could spend hundreds on all the wrong things.

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