1991.5 W250 Charging issues Fixed

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1991.5 W250 Charging issues Fixed

Postby BradPA » Sat Aug 01, 2020 4:32 am

Hello all... its been awhile in fact years since i have been here

OK i have had charging issues for years. tried most everything suggested on here and the web
this problem was not consistent charging voltage would go from 14.7 to 15.7 and up ..
burnt up batteries .. replace voltage reg ..

fix is in the wiring ..
Blue wire (start run) from bulk head or big plug on fire wall runs in wiring harness
this wire also go to fuel shut off, vacuum sensor, alt , regulator .. computer

well this one blue wire from bulkhead in wiring harness.. is split into 5 more blue wires
this connector is crimped and is in the wiring harness .. right behind the brake Vacuum booster in wiring harness
looks like a cheap copper or brass connector with 6 wires in one crimp. .. this is called the J1 splice

replace this connector.. re-crimp.. and my voltage dropped from 15.9 to 14.7
EDIT ,,holds 14.2 with lights on .. 15.9 with heater fan on full.... hmmm

I hope this 15 min fix saves you lots of money,,, hell I hope you understand my typing
Have a nice day
Last edited by BradPA on Mon Aug 03, 2020 6:45 am, edited 2 times in total.
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Re: 1991.5 W250 Charging issues

Postby PToombs » Sat Aug 01, 2020 6:28 am

Good find! The usual fix is to use a relay to bypass all the blue wiring so key is on it feeds battery voltage direct to it. The bad connection you found causes a voltage drop making the alternator over charge to compensate.

Just enough power to break everything behind the crankshaft.
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Re: 1991.5 W250 Charging issues

Postby BradPA » Sat Aug 01, 2020 7:44 am

Thanks .. took me awhile to figure it out.
the fix took less time than me trying to find this site again,,,LOL

I think 14.7 is ... OK I would like to see 14.2 .. maybe a few other connectors need looked at

This bad connector.. maybe ok till it warmed up and current ran thro it.. then i would jump to 15.9 + was not consistent
now it is...
one other splice .. fuel shut off .. Blue wire and fuel heater. splice is near fuel filter .. i no longer run the heaters. and did a comp delete

remember this is all on the start run.. where voltage is read
Thanks again,.,, Brad
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