95 T100 Must have electrical short somewhere, can’t find it
 

Been trying to get back on the road for a few weeks now.

There’s a lot to the timeline, and I read on here that the more details, the better, so I’ll do my best to be thorough.

July - was headed to fairgrounds, truck was running great, no issues, and died while idling in the driveway. Turns over but will not start. Hubby suspects fuel pump.

Dec - hubby gets around to replacing fuel pump. Seems to do the trick, but had some trouble with the connector plug. Dies as I’m driving from my office to pick up kids from basketball. Tow it to our local mechanic who messes with a fuse, fixes the connector for the fuel pump, and we’re back on the road, sort of.

No fuel gauge, turn signals, no gauges, no brake lights , nothing. Hubby replaces all fuses, all systems are go again except fuel pump. Ok, we can live with that.

Drives great for a few days, then on Fri 12/29 won’t start when I go to leave the salon. Get jump started and get all the way home, about 15 miles. Hubby replaces battery. Back on the road.

Drive to work on Thursday (15 miles or so) and everything is fine. Head home that night, and check engine light comes on. Cautiously head home after checking oil and water. Get another mile down the road and I notice headlights are dimming. Still headed for home and lights go super dim so pull over and call hubby. He comes with the big Dodge, charges it up, get home fine, no issues.

Over the weekend, take out alternator (about 3 years old) and have it tested. Alternator is good. Now we are looking for a short or bad wire or loose connection from the alternator to the battery or from the alternator to the fuse box. Hubby doesn’t like the look of the alternator connector plug so we head to pick and pull to find replacement. Get one off a Toyota 4-runner. Splice that in, weld up the joins, wrap with wire, hubby doesn’t want to get into this again. Cleans all the connections to the battery so they are nice and shiny, cleans the ends of the ground wire, looks shiny. Charge up the battery, starts right up, everything looks good, lights, wipers, blowers, etc.

So I drive to work this morning. One stop to pick up another kid, 2nd stop to drop 2 kids off at school, go to office. Everything is great. Tonight, go to head home, and I get a mile down the road and notice wipers going in slow motion. Find a safe place to pull over, call teen daughter to come charge up enough to get home, hopefully. Charge for 15 minutes, starts up, head toward home. Get about a mile down the road and slo-mo wipers again so I pull over. Hubby on his way.

Now, it’s parked at a friend’s house because we charged it up but he didn’t think it would make it all the way home.

Now, I’m posting here because I’ve been googling the crap out out of the “new battery, good alternator, not charging battery” scenario for my truck. So I have a few ideas of my own but we attempted the quick easy things first. I suspect the crummy trailer harness hanging off the tow hitch, and I also think we have an issue in the driver side kick panel fuse box because there’s fuses there that help control the charging system and the various gauges and lights and such that weren’t working when the truck came back from the shop the last time. I know the big 30a and 40a fuses under the hood are good, checked them and the big 80a fuse yesterday when we replaced the alternator connector plug. At my insistence, we bought an analog multimeter yesterday but we aren’t too sure how to isolate where our issue is.

We work on the cars together, because hubby can fix stuff but I have the smaller hands to get into the tight spaces, etc. we have learned to be a team but neither of us is good with electrical. So. I ask for the combined experience of you all and hope we can get old blue back on the road soon. I despise having a car payment, but as hubby pointed out today, we’re about 3 car payments into this debacle in the last several weeks!

Thanks in advance!

Heres my advice, After owning dozens of T100s in my family and working on them my whole life, Check that box for the pigtail connection under your trailer hitch, And install loads of grounds. You can buy grounds from Orileys or places like that. Ill show you pics of my grounds https://cimg4.ibsrv.net/gimg/www.yot...5d62494aaa.jpgThis engine has been in my life since it was new and ill never get rid of it. Survived a T bone and alaska. I live in Utah and it loves cold. Has 322k miles and it is perfect. ( brag rights sorry) anyways lets jump to it.
https://cimg6.ibsrv.net/gimg/www.yot...b6abb8915a.jpgHere is a ground from alternator to sidewall. Run grounds from your alternator to Sidewall, Sidewall to battery,Battery to alternator, Etc.
https://cimg5.ibsrv.net/gimg/www.yot...e692ac2839.jpgGrounds from intake to sidewall.
https://cimg1.ibsrv.net/gimg/www.yot...26a8720c51.jpgGrounds from valve cover to firewall. I would also run some grounds from block to sidewall, and head to sidewall. And maybe even head to battery. Make sure you use a wire brush to clean every surface well so you have good contact. And just find random bolts around the engine bay to avoid making new threads.
https://cimg5.ibsrv.net/gimg/www.yot...2cb3dba4c8.jpgAnother shot from the previous ground. This might be harder for you because i gutted my entire A/C system.
I would also check your 80 amp fuse for alternator in fuse box. Check all your fuses and also check the fuses behind the drivers foot panel. If you need more help just respond to this post

:google:
Parasitic draw & Voltage drop testing.

In short.

Voltage drops. Meter set to DC voltage, measure from one end to another on a section of wire(or across a fuse) while the circuit is drawing power.
Example, key on engine off put one lead on the battery positive post put the other on the fuse block where the positive wire (actually a fusible link wire) attaches to the fuse block. A low voltage reading is a good reading, a few hundred millivolts. If you get negative voltage readings just swap the test leads around (black for red where you're measuring)


Parasites. Key off engine off, meter setup for current measurements (10amp/10A) pull a fuse and measure across its two terminals on the wire harness. Anything other than the radio (maybe the ECU) should read zero or near zero.

Extra credit, measure the voltage between the alternator output post and the battery positive.

Another tip, if your engine is off you should see something around 12.3 volts on your battery if it is charged. when the engine is running you should see around 14 or at least see an increase from the engine off voltage, otherwise your battery is not charging and you should not take the kids to school with it until you get it fixed.
Also, do not brace your engine to the inner fender like the pictures above, not sure what the theory is there.

I didnt tell her to brace her engine. I was just showing the grounds . I have seen serveral engines not run right or not charge, then after cleaning grounds or installing new ones they run great. The braces in my truck are only their because i put them their. They are their because i didnt want hoses or wires getting grabbed by my steering because when you do a 3.4 swap, sometimes wires are everywhere. No theory their and its not like a brace for the engine, They are just some old tubes from a mirror i pulled off a old ford rv. Anyways good info you have, But i still agree that she should at least install a couple grounds and go from their.

We are tackling this again today - will report back what we find. Battery is charged up, going to take a look.

Sweet. Wish you best of luck. Keep us posted