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GEN1 08-02-2013 11:52 PM

93 ram RPM/Voltage issues
Has anyone ever seen the issue of the rpm guage dropping dwn to 0, and at the same time the battery voltage starts to drop also, as soon as the RPM guage starts "marking" the voltage starts to go back to normal? Any help will be greatly appriciated.

crazzywolfie 08-03-2013 02:13 PM

it almost sounds like your loosing power to the gauges. never heard of something like this.

GEN1 08-04-2013 11:56 AM

Yeah, I know it sound weird, but it happens every time consistently, the rps drop to 0, and then the voltage starts to drop. sometimes for 10 seconds, sometimes up to 20 mins. doesn't matter if it is sitting idle or doing 60 down the road. I spent some time yesterday looking for a loose connection, didn't find any. Is it possible the crank sensor is going bad, I'm assuming that is where the rpm's are being measured. Here is the pic of the sensor Although I still don't see how it would affect the voltage the way it does, any info would be helpful.

GEN1 08-19-2013 10:07 AM

Update: I solved the issue, turns out that the alternator was "going" bad, had it tested, and was "good", but just barely making the mark to be good, fortunately the tech was paying attention to the numbers, and said it would go bad in a short amount of time, and since it was still under warranty he went ahead and replaced it, upon verifying my information for the vehicle, he noticed that the alternator the truck called for was not the one I had in the truck. the one I had in the truck was for a gas engine, not the diesel, which was a little aggravating, since "they" were the ones who gave me that alternator less that a year ago. Anyway, the diesel one needs the 120 amp, the gas I believe is only about 80/90 amp. So, in theory the alternator could not keep up with the demand and would ultimately "give out" and cause the RPM gauge to drop and the voltage also to drop, since it was not putting out anything, and the truck was just running off the battery at that point. I installed the correct alternator, at first, the rps were still at 0, and voltage low, I then adjusted the gap on the speed sensor (which I had replaced with a new one thinking it was the issue) and the rpm's read normal and the voltage jumped up to normal. From what I understand, the voltage is regulated by the pcm/ecm, which uses the engine speed sensor to verify the engine is running, which in turn tells the alternator to put out more volts?, In my case, the ess was good, but the alternator seems to have shorted a diode and was no longer putting out any voltage.

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