Electrical issues on 1993 W250

[RTRAM]

The truck has been running great and now I have had a couple of electrical problems and I don't know if they are related. its a 93 w250, with 210,000 miles and pretty much stock

My wife was driving the truck and it just died. We got it home and found that the fusible link at junction A0 on page AD2 of the factory service manual. I replaced that with a real fuse. The manual says that the link was a 20 gauge fusible link that goes into a 12 gauge wire going to the ignition switch. How large of a fuse should I use. I have 20 amp, but that seems really high since most of the power goes through relays. What is a reasonable fuse size?

Also, I just replaced the alternator. I got the check engine light on the way to work this morning and diagnostic codes were 12 (for disconnected battery) and 47 for a low voltage on the alternator. I took the alternator in and they checked it three time and in passed all three times. The output was 13.8 volts on the main output terminal and 13.8 and 10 volt on the field terminals. The book says this is supposed to be less than battery voltage, but how much less. Even when advancing the throttle, it didn't go much over 11 volts.

Has anyone rewired the truck to take out the fusible links and put in fuses. It is very difficult to replace those fusible links.

 

[DVolk]

I eliminated my fusible link with no issue and have done so on gassers you can get them but there spendy , but have issues .
you should be getting atleast 14volts , more like 14.8 you might check your cabel connections to make shure there all good at both ends , ive had to wire wheel the corosion were it turned green before , use grease or vasaline on the terminals

 

[JLEONARD]

Last time I replaced fusible link it was a ten minute job and lasted a good five years until I gt rid of the car. Sometimes a simple R&R is the easiest and most cost effective.

 

[Bob Beauchaine]

I had electrical issues a couple of years ago that cost me an alternator, starter and both batteries - yes I do run a dual battery setup that can give me 1500 CCA. It all started when my alternator died at about 240 K. I lost the alternator 3 weeks prior to all this but the OEM gauge read that all was ok. The batteries were so dead that they could not even be trickle charged. It was early summer and light enough so that I did not need lights going to work so after 3 weeks the truck would not start. I had both the alternator and the starter rebuilt (by a reputable rebuilder), replaced the batteries. All but the batteries failed within 6 months. I said the heck with it and got a starter from Cummins and a new lifetime 136amp alternator from PA alternators on line. Then I wired in an after market Auto Meter volt gauge through a SPDT switch so I could read volts while running or prior to starting. It all cost quite a bit but works quite well. I would suggest that you might want to put in a volt gauge. BTW my alternator reads 14.5 to 14.8 volts while running and momentarily drops to about 10.5 when the grid heaters are on.

Bob

 

[EDankievitch]

I found that the connections on the wire harness are not sealed road salt gets into the wires and rots them out from the inside. I had to replace the harness on the 89 that I use to own. too many wires to try to re-splice. it wasn't that bad a job to change out the harness. you might want to look into getting one, harness and doing it on your truck before things get worse.

 

[B.G. Smith]

I have an old Hanes manual and it shows the fusible link in the 12 ga wire to be 40 amps. bg

 

[GHarman]

My 91.5 had serious wiring harness issues. Road salt! Had it replaced.
When the issue was with the Alternator, it seemed that charging was controlled by the brain box under the left front fender as it under charged with a rebuilt alternator. After replacing the Brain, I had no more issues, there.
Now I have the '93 and believe my serpentine belt is slipping. Changing that out with a Gates HD belt. Could your belt be slipping and not providing adequate RPM's to the alternator??? Just thinking out loud?
GregH

 

[JLEONARD]

Pretty rare for a serpentine belt to slip. My experience is they work even when they start to shred.

 

[Bob Beauchaine]

I tried a Gate tensoiner and before the day was out it started to squeal so bad that when I got home I put the original Cummins one back on. BTW the belt had started to track into a position that would have eventually caused it to shred. That's when I noticed the difference between the Gates pulley and the Cummins pulley. Looking at the Cummins pulley it has a slight cap at the center of the pulley and the Gates does not. The end result is that the Cummins pulley keeps the belt centered and running true, another reason why I will opt for Cummins parts when possible even though they are higher priced.

I have seen the damage a broken belt can do to the radiator and other parts up front of a rear wheel drive vehicle.

Bob

 

[GHarman]

Yep, a Gates Belt and a Cummins tensioner!
Thanks Gents!
GregH

 

[Brownee]

I have a 93 w 250 with a 94 Transmission *it wouldn't charge so I put in a Voltage regulator it started rt up we drove it to tag it and to eat lunch and it won't start the only noise it makes is the loud click of the starter kicking we had the starter tested it was good they told me the battery was bad so we got a new one ( it was not bad and I knew it but I bought a new one) nothing still the loud CLICK so I took the battery back and got the starter nope that didn't work still the loud CLICK. I at a total loss as what can be wrong. Help please russell

 

[Bob4x4]

check the voltage drop to the starter

 

[Brownee]

I checked the voltage at the battery at 12.4 then I checked the voltage at the starter it was also 12.4 should I check it while trying to start it?

 

[KOG]

Well, yeah, you have to check voltage at starter under load, i.e., when you're trying to start it.

 

[DVolk]

I had a positive Batt cabel go bad on me with internal corrosion so that could be bad