Alternator not charging

[DJP]

The alternator in my 93 is not charging the battery. I removed the alternator and had it tested twice, and both auto parts stores reported the alternator is working OK. The battery is good, and the cables are clean. Any ideas in what the problem could be? Does the 93 have an externally mounted voltage regulator? if so where is it located?

 

[Philip]

Your 93 does not have a external regulator. The PCM controls it.



Is your tach working properly?

 

[JFaughn]

Check this site , parts , mods , and info for repair .

LarryB's Dodge starting problems solved here.

 

[HRDROKN]

Check the crank position sensor... (if you have a factory tach and it works fine then the sensor is ok) if the sensor is bad then the pcm does not know the engine is runing, therefore no charge signal. I had a pulley wear through one of my wires to the sensor... caused intermittent operation to none at all.

 

[KSommer]

it's not hard to add an external regulator. my friend (also a '93 owner) had to do it 600 miles from home in the autozone parking lot. that was 8 years ago, still working great.

kent

 

[DJP]

The Isspro aftermarket Tach is working OK. The PCM that you refer to, is that the large box that sets behind the battery in the L/H fender cavity? Does the alternator field circut somehow pass through the PCM? I don't have a factory manual or a wire diagram, so troubleshooting this problem is a little more of a challange. I think if I have a bad internal circut in the PCM, the external voltage regulator install / modification may be the cheapest and easiest fix for this problem. Question is, how do I wire the external regulator, and what P/N regulator do I purchase?

 

[charliew250]

I went through the same thing a coulple of years back. I was in the process of tracing wires to install an external regulator when I found one of the relays on the left fender was corroded and not working. Replaced the relay and plug, problem solved. If memory serves me the relay is the trigger to the PCM for the charge circuit. The relay was called the "shut down relay".

 

[GIT-R-DONE]

it's not hard to add an external regulator. my friend (also a '93 owner) had to do it 600 miles from home in the autozone parking lot. that was 8 years ago, still working great.

kent

I was wondering how that was done? Do you know, or know where the info is for doing that? Thanks

 

[KSommer]

i think he picked up the regulator for a '78 ish truck, and wired it to the alt according to the directions that came with it. make sure it has a good ground, or it still won't charge.

kent

 

[DJP]

Problem solved

Found the problem. It was an aftermarket battery isolator module wired in for RV coach battery isolation. Apparently, the diodes blew out in the module, not allowing current to flow from the alternator to the battery. Thanks for the replies, and the ideas on where to look.

 

[3dracer]

I also found the wiring harness behind the rear valve cover had fallen out of the original wiring harness and was rubbing against the rear valve cover. It had rubbed thru the insolation and was discharging intermiitingly,,,,some times not charging at all. Just another idea for anyone else who has problems.