CHarging issues(RJM)

BroncoMatt13 · Jan 8, 2012

i recently installed a new rjm injection harness into by previously injected 5.0 and at first all was good and my 3g charger(also from RJM about 5 months ago) was charging at ~14volts no problem, but now it is only charging at 11-12. this problem seems to have sprung out of nowhere as it was working fine with the new harness a few days ago. i got the alt tested and it tested good. any ideas?

garberz · Jan 8, 2012

Do you have the "hot in run wire", from the Ign. switch hooked up to the "I" terminal on the alt? It's the same circuit as the oil pressure sender and the coolant temp sender. They're 3 wires, the third is the one that gets hooked up to the "I" terminal on the alt.

BroncoMatt13 · Jan 8, 2012

yes, if that is what the supplied alt connection is for

hyghlndr · Jan 8, 2012

Did you check the belt? Mine looked tight but was actually slipping slightly. The first few weeks was no problem, then the new belt stretched. Picked up a 1/2 shorter belt, used pry bar to re-tighten.

BroncoMatt13 · Jan 8, 2012

it is tight

malonejy · Jan 8, 2012

Where are you getting the reading from? Could be a bad gauge or wiring. I just had a similar issue and it was a ground wire for the gauge.

BroncoMatt13 · Jan 8, 2012

malonejy said:
Where are you getting the reading from? Could be a bad gauge or wiring. I just had a similar issue and it was a ground wire for the gauge.

i am taking the reading at the batt

bluesbish · Jan 8, 2012

FYI, charging 11-12 volts is actually not charging at all

BroncoMatt13 · Jan 8, 2012

bluesbish said:
FYI, charging 11-12 volts is actually not charging at all

yea i know... i just didnt wanna be that negative lol

bluesbish · Jan 8, 2012

recommend doing basic tests of the charging circuits. voltage drop the b+ and ground. test for b+ at the regulator and make sure the jumper from regulator to stator circuit is good. maybe knocked something lose during harness install. what are the symptoms that lead you to checking charging voltage?

BroncoMatt13 · Jan 8, 2012

bluesbish said:
recommend doing basic tests of the charging circuits. voltage drop the b+ and ground. test for b+ at the regulator and make sure the jumper from regulator to stator circuit is good. maybe knocked something lose during harness install. what are the symptoms that lead you to checking charging voltage?

it is a 3g alt with the regulator is internal(http://www.rjminjectiontech.com/collections/alternators). i noticed that when driving around my voltmeter was at 10v when it was 14v before. and i was having trouble with start-up needing lots of jumps.

bluesbish · Jan 8, 2012

I understand that the reulator is bolted to the alternator. It is a charging system concern and should not be difficult to diagnose. with the engine running, place a voltmeter on the positive battery terminal and the B+ post on the alternator(the one with the big heavy wire). should be less than 1/2 volt. then do the same from the negative batt terminal to the alternator case. again, should be less than 1/2 volt. then unplug regulator connector and using a test light, check for power to the regulator. then reconnect regulator and unhook the small single wire connector. start engine and check for power at the single wire connector.

malonejy · Jan 8, 2012

Check the voltage right at the charging stud on the 3G. If it's not good and you're sure the belt is tight, alt is problem.

BroncoMatt13 · Jan 8, 2012

ok, i will try these two tomorrow

bluesbish · Jan 8, 2012

Check the voltage right at the charging stud on the 3G. If it's not good and you're sure the belt is tight, alt is problem.

This is not completely accurate. there is more involved. sorry.

malonejy · Jan 8, 2012

I realize it could be the volt reg (which I'm considering part of the alt), or probably a few other things that I wont pretend to understand, but if it's not getting good voltage right off the stud, I would take it to an alternator/starter shop and have them check it.

Just trying to help

bluesbish · Jan 8, 2012

Just trying to help

I know you are and you are not completely off base on your suggestion. Just wanted to make sure the OP understood that there are a few other things going on in the system as well. Including battery condition as well. a shorted battery or bad cell could give similar problems. Without a schematic in front of me my advise might not be 100%. But as far as the voltage drop tests and checking for a few powers to the alt., I know that will get you a good the OP a good start on diag.

BroncoMatt13 · Jan 8, 2012

bluesbish said:
Including battery condition as well. a shorted battery or bad cell could give similar problems. Without a schematic in front of me my advise might not be 100%. But as far as the voltage drop tests and checking for a few powers to the alt., I know that will get you a good the OP a good start on diag.

Thanks for the help, the battery is less that a week old and as i stated earlier i did get the alt/reg tested at the parts store and it passed.

with the test u stated earlier is there anything specific i should look for? ie with the light, where there should and shouldn't be power?

also, how is a battery shorted? i use the side lugs and i have shorted it to my dipstick and welded my wrench before but i assume a incident wouldnt cause long term damage?

Viperwolf1 · Jan 8, 2012

Make sure you got 12V to the green wire with the ignition on. If you don't the alternator will not do anything.

Shorting a battery with a wrench can cause long term damage to the battery and the wrench. It can also damage the alternator if the engine was running at the time.

BroncoMatt13 · Jan 9, 2012

Viperwolf1 said:
Make sure you got 12V to the green wire with the ignition on.

got 12v

malonejy said:
Check the voltage right at the charging stud on the 3G.

reading the same voltage here as at the batt and everywhere else.

CHarging issues(RJM)

Full Member

Bronco Influencer

Full Member

Bronco Guru

Full Member

Bronco Guru

Full Member

Full Member

Full Member

Full Member

Full Member

Full Member

Bronco Guru

Full Member

Full Member

Bronco Guru

Full Member

Full Member

electron whisperer

Full Member

Similar threads