jdgroh

first off problems started about 6 months ago and i have been working on since. around july of 2010 parked jeep and went to start dead battery, replaced battery with new one, then would not fire replaced coil, pickup coil (under distr. cap), dist. cap, rotor button, plug and plug wires. 2 weeks later jeep just dies no power to anything, would not start no spark from coil, waited 2 hours and started and runs, now the big problem and only problems left

1) when starting very cold natured wont idle cold, replace the tps

2) this is my main problem i need help with over charging at about 16.8 volts
i have replaced my computer and my altinator and i do have a new battery and i am still overcharging, anybody have any ideas

anybody please help thanks

tjwalker

Is 16.8 volts verified with a meter?

If not, you need to do so as to be SURE that you are still overcharging.

Can't 100% trust the gauge.

jdgroh

yes checked with digital voltage meter

xj^REMY

new alternator & computer, or refurbished??

could possibly be voltage regulator in the ECM

have the alt tested at a dedicated shop....i had a junkyard alt tested at 2 local AAuto & AutoZ a few months ago, one said there was an "internal short circuit", causing it to "run backwards" & fail on their bench, the other passed 3 times & they "confirmed" it was a 136A alt.....went to a dedicated shop, & they told me its avg output was 90A

no longer trust autoparts stores.....these stores dont test voltage output, just if current flows thru (if hooked up on their bench, correctly)

in your case, im thinkin voltage regulator

if the alternator is operating correctly, it'll output somewhere around 70-120ish Amps.....regulator will regulate the alternators voltage output in the computer by measuring the stator & battery voltages, with those measurements it adjusts the amount of rotor field current, which influences alternator output.....there's something that the regulator is measuring (or not) that is making it call for more "flow" & charging the battery to 16.8

checked all ur grounds??

thats all i can come up with, hope somethin helps

jdgroh

going to check grounds, i am going to start at neg side on battery and work my way around, i did replace the voltage regulator which is the computer. unless there is another voltage regulator? that i dont know of if so where is it located thanks

Zab243

mine charges at 16.7 on the voltage meter, i personally dont mind it for the extra power, and what not lol

jdgroh

i just dont want it burning up my electronics like ignition system, etc. also electronics thru cig lighter cell phone charger inverter, etc.

tjwalker

Kind of high and definitely hard on your battery. The target voltage charging rate is around 13.5 to 14.0 volts, give or take a bit.

I'd look into resolving this.

thorguy57

Do you have 12V back feeding to the alternator from a different source energizing the field?

jdgroh

sorry i dont understand what you mean, how do i test for that?

thorguy57

I am not sure exactly how these alternators are wired up. Most of them use a wire to control the field current to start and stop the alternator from charging. With the field energized, the alternator puts out. When there isn't 12 volts it stops. If the computer is stoping the 12volts to the field, but something else is sending 12 volts to it, it will continue to charge. It looks like from my book the dark green wire on the alternator is the one that would control the field. Check to make sure this isn't getting 12volts when it is charging at 16 volts.

thorguy57

Also check all your grounds and make sure they are good and clean. Also ohm out the Dark Green wire between the ECU and the alternator and make sure there isn't a high resistance. This could also cause overcharging issues. Make sure all the wires are good in the connection on the alternator.

xj^REMY

so did u get a NEW computer & alternator?

only 1 regulator, in the computer (ECM), so basically the regulator is the ECM

so lets back up a little, maybe suttins missing....jeep died, u got new battery, still no good so u got NEW (?) coil, pick-up coil, dist cap, rotor, plugs & wires...then it ran & died 2 weeks later without anything having been done??
u waited 2 hours (didnt touch anything??) & it started & ran.....the problem when idling cold was solved with the new TPS??....& you noticed the battery charging to 16.8, so you replaced the computer & alternator, & still having the overcharge problem???

as far as the field wire, it should be 1 of 2 on the back of the alternator....you prolly have the integrated plug with 2 green wires....ive got a molded rubber block with 4 o-ring terminals.....in my case, one wire goes to the starter & the other is the field wire that goes to the ECM

so, thorguy, what ur sayin is when the battery is fully charged (12 - 14.5), there shouldnt be a reading in the field wire

xj^REMY

.

thorguy57

Yes thats typically how it works. When the battery is charged the voltage regulator will shut off the field current which will stop the alternator from putting out anymore. This happens a lot usually and a lot of times a minute