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Discussion Starter · #1 · (Edited)
Had not driven van since friday, was on holiday, then sick. Its been raining a lot.

On ny way to work today, made it about a mile, van was running normal, pull up to drive through to get coffee, van died and wont start.

When i turned they key, gauges an dash lights work, engine cranks over but doesnt fire.

Got my coffee, pushed the van into parking lot. 4500 lbs and a 1000 in tools is heavy whew!

Started checking fuses. ECMB is blown. Replaced it cranked it over, same thing. Checked the fuse and it must have blown again immediately.

Whats a good strategy for tracking the problem down. Never had this issue before with any car.

Thankfuly im self emloyed so i wont lose my job but was going to be working with another guy today so im pissed this happened on a day when it will affect anothers schedule.

Thanks guys!

Edit: looking at the schematic in van manual. Looks like ECMB goes to fuel pump and fuel/oil pressure switch? Cant see anything else thats running off that fuse.
Schematic Rectangle Font Slope Engineering


Edit2: so looks like it says "hot at all times" on that fuse.

I can put a new fuse in and it doesnt blow unless i turn the key. I just tested it and as soon as i turn ignition on SNAP the fuse blows.

Edit3: the side of the fuse thats not suposed to be hot has 0.3v coming out of it with key on, 0.4v when key off. Glad i checked to see it it was hot before testing resistance. Going to unplug battery and test continuity on that fuse pin.

Edit4: here is where things get strange and spooky...

I disconnected positive battery lead. Not sure why but i tested that pin again for voltage. Sounds stupid to do so right? Still getting 0.3v out of there! So with the battery disconnected where is this coming from?

Im starting to wonder if my battery is is leaking or something. Due to the heavy rain it looks like water was leaking under the hood and the battery is sitting in a puddle of water. Theoretically if theres a crack in the battery could current be leaking to the frame that way???

I was bork here but 9 months out of the year i hate the PNW but cant move because my wifes family is here. Would live to live in the desert lol.

Edit5: here is the strange part. I pulled the battery, and tested the positive battery lead to the battery holder plate. Still getting a small amount of voltage? Is that even possible? If enough battery acid leaked onto the plate could it basically create a mini battery there? Its not much but you can see in the picture what im talking about:
Automotive tire Motor vehicle Gas Vehicle Metal

The battery tests at 12.6v, it was sitting for days and van fired right up this morning. So in a sense the battery is good but its still the same battery that was in the van when i bought it in 2018 so it wouldnt hurt to replace it. im only a block away from auto parts store.

Edit6: i just tested that fuse pin again and with the battery unplugged it still has 0.3v coming out of it, what the hell lol. Maybe its my multimeter. Going to walk home and get my klein and see if its the same deal. Man this is twiglight zone shit rigjt here.

The only other thing i can think of is the reptilian shadow government installed a mini nuclear or battery powered tracking device on my van somewhere while i was on vacation and its shorting to ground a little or something hahaha jk.

Edit7: walked home and got my klein. Still getting 0.25v coming out of that pin with the battery removed. Has been removed for about 45 min. Going to touch positive and negative battery terminals together for a few min to see if that gets rid of that... maybe theres a capaciter or coil or something that still has a charge in it???
 

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Discussion Starter · #2 ·
Well ive been home wracking my brain and trying to research a good game plan while i wait for the downpour to stop before i head back to try and figure this out. Im just going to ignore the impossible voltage for now as there is nothing at all that could be causing that. The battery is completely removed sitting on a board in the back. Either theres electricity coming out of the air or ground or im just hallucinating. Have never seen voltage off a car with no battery before.

I think my first try is going to put a 20amp fuse in instead of a 15 and see if it will blow that. And if that doesnt work a 25. If that blows im going to get it towed, dont want to have to keep walking a mile each way to try something on it.

Am going to test the fuel pump relay first and see if thats bad. If it is it will be a week before i can get one in.

Am also going to trace the wires in that circuit as much as i can see if theres anything suspicious.

Just getting over being sick so still not feeling too great not sure if i can wrap my mind around this today.

Ive been reading other related threads here but still confused as heck on how to diagnose this.

Any advice appreciated as always.

Thanks
 

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You likely will end up finding a chafed harness.

Common issue on 2nd gen vans… There are metal clamps that hold it, they had rubber inserts when it was new but the rubber fails and the edges of the clamp chafe through the plastic loom.

Not sure if 1st gen had the same clamps but might be a reasonable thing to look for.

For the ecm1 fuse I know a couple common spots…. Not sure about the ECMb fuse.

Might start with a careful look behind the air conditioning compressor…. The challenge is that once you handle the harness in several places and the problem “goes away” you may not find the one wore that was chafed until it happens again.

Good luck….

It’s not gonna explain that .25 volts though….
 

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Discussion Starter · #4 ·
Well just got back from walking down there and poking around until it was too dark to keep going. Tried a 20amp fuse and it popped quick as the 15. Decided to not try any higher.

Pulled the fuel pump relay, hooked some lead wires to it and tested it on battery to see if it would trigger. Was able to get it to make a noise but it didnt sound quite right and the terminals were covered in some odd looking black goop. Auto parts next door to where im parked (conveniently) said they could have one in tomorrow. Not sure if its that but i figured in case it is why not.

Left the relay off and put a fuse in, turned they key on and it didnt blow.

So it would make sense the short is either the relay itself, or between the relay and ECU, or between relay and fuel pump. Basically im hoping that test rules out a short between fuse panel and relay is what im saying.

My wife is on her parents AAA still i think, going to see if i can get it towed home tomorrow.
 

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Unplug fuel pump relay and test. Woops, you beat me too it.

Ok, the "black goop" was dielectric compound GM used to use. You probably have a bad fuel pump, or the wiring to it.
As far as your meters, that is why I use Fluke. But, you have to remember not to touch the probes, or touch the hot, and have skin touching the body of the van.
A cmmon place for the wires to rub through and ground out is, if a 4.3, engine cover off, looking down, harness comes back, makes a turn on/close to the valve cover on your right. And,yes, a fuel pump wire is in it there.
 

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So, that fuse will power the fuel pump through the fuel pump relay and the oil pressure switch, it also powers the ECM. I would disconnect the fuel pump connector and try again to see if the problem is between the fuel pump relay and the connector, or between the connector and the fuel pump.

Oh and please don't ever replace any fuses with a higher rated fuse, it's sized to protect the wiring and prevent a fire.
 

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1998 LS AWD Forest Green metallic
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With regard to Digital Volt meters (DVM') ...and I own and use a couple of high quality versions:
One drawback to using a DVM is that is will measure very small voltages without providing ANY load to the circuit. In electronic circuits that used to use tubes, that was a significant improvement from the old analog (meter movement) voltmeters, and a big selling point. In many applications they replaced bench-top meters (VTVM's) that contained vacuum tubes and that needed to be plugged into a wall outlet to operate.
The very high resistance (impedance), of the input of the better DVM's means it does not take any power from the circuit under test (The exact purpose for which the older VTVM's were utilized ), and the new DVM's were battery operated, so very portable. An old analog meter ( with a moving needle) takes a small amount of power from the circuit to operate the meter. In the case of very small voltages, often the analog meter consumes the small amount of power available, and you do not even know it was present. A DVM can measure that very small amount of voltage, without consuming it. It can be from the very small amouint of voltage on the grid terminal of a vacuum tube, a charged capacitor which is designed to retain memory in a radio, computer system or or some other electronic circuitry .
If you are measuring anything below a volt, it probably is not significant unless you are working on very sensitive circuits designed to run on about 2-3 volts or less.
A good test to see if this 'residual' voltage is anything to be concerned with, is to place the leads of an analog meter across the measured voltage, and try to read it. Most likely the indicated voltage is drained to nothing. You can place the leads of the DVM in parallel with the analog leads to see what the DVM reads with the very small drain of the analog meter in place.
For most, if not all, automotive uses; a cheap analog meter will give you all the accuracy you need.
Another advantage of an analog meter...you can see the needle move and get a pretty good idea of what is happening at a glance. Most of the time you are not interested if the voltage measured is 11.9 or 12.2. Depending upon the meter, if you are on a range of anything over 12 volts, you can often see what is happening , and often from several feet away, and in poor light. You do not have to study the digits and look for the decimal point.
Nowdays DVM's are ubiquitous and very inexpensive. My old Harbor Freight one was free with a coupon, and should do almost everything I could need it for, except it is in a very fragile plastic case...so it lives most of it's life in a tool box in my van. I just have to be sure to make sure the battery has not corroded from lack of use.
Rod J
Issaquah, WA
 

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Yep, and a Fluke will do the same thing, not specific to any brand.

For most, if not all, automotive uses; a cheap analog meter will give you all the accuracy you need.
I agree but virtually never recommend that anyone go out and BUY an analog meter. If you already have one, sure you can use it but an auto-ranging digital meter is going to be easier to use(esp for someone new), easier/quicker to read, more accurate, wider range, more durable if you get a decent model, more versatile, and safer for your test subjects ;)
 

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I am old school and still use my old Simpson' s quite often.
No. I would not recommed buying an analog meter either.
Astrowill is right about that.
I think a new good qualityy analog meter costs more than a good Fluke DVM now.
You can buy a very good DVM in very good rubber case that is virtually unbreakable, for considerably less than a Fluke branded meter. The Fluke meters were ( may still be) pretty much considered the top of the heap, for quality and reliability.

Rod J
Issaquah, WA
 

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Discussion Starter · #10 ·
Yeah i have a harbor frieght one that is great for basic stuff, then a better quality klein that does the fun stuff like current, diode tests, continuity and all that too. Guessing the klein is more accurate.

I just got the idea of using my klein to test the current flow of the residual voltage. Im guessing its in the low mV level.

Just because i was curious, i put my voltmeter on the parking lot pavevent, and was reading 0.2v. When i got home i tried it in the street at my house, 0.02v.

Maybe theres just some sort of charge in the air there in that parking lot lol...

Unplugging the fuel pump and testing seems like a good next step.

Thanks for all the input guys. This has been quite discouraging to me but i know ill figure it out eventually. Ive been learning and experimenting with hobby electronics recently, microcontrollers, logic lvl circuits, power supply circuits, using resistors, diodes, mosfets, etc. So i feel like my electrical knowledge is a little more advanced than a year ago and should help with tracking this down. Had an issue on a circuit board that had 8 buttons and other sensors on it that wasnt working and took an hour or so but was able to find a solder joint that wasnt right that was messing the whole thing up.
The wiring harness is a bit more daunting because its a fat bundle, but its a similar concept.

Going to tow it home today and work on it until i find the issue.

As much as i love my van its old and beat up and I get fed up with this thing sometimes and hit craigslist looking for another car, ive done this several times but i cringe at having to learn a new car and its unknown issues and quirks. My theory so far is in my budget any car i buy is going to have problems so why not keep the one i already have and know whats what on it.

But not a lot out there that can keep your stuff dry AND get 20mpg. Was surprising the entire lack of vans in general on craigslist. Would love a truck, but accessing tools in a canopy is a pain and less secure than a van. Plus the MPGs. Even if i get a new work rig at some point if the van runs ill keep it for camping etc, have more in it than i could get out of it and only has ~200k miles.
 

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Discussion Starter · #11 ·
I left the relay plugged in, unplugged oil pressure switch, and turned her over. It would start for a second then die. Fuse didnt blow.

Plugged oil pressure switch back in, fired right up, cant get it to die or blow the fuse now...

I had taken out the two 30A Horn and PWR ACC fuses while trying to trouble shoot because A. Neither of those things have ever worked and B. Theres so much water leaking in my driver side door figured that could be shorting something.

I dont think that was it because tried again with those fuses back in and cant get ECMB to blow again...

I didnt "do" anything other than unplug and plug relay back in, and oil pressure switch.

Scared to drive it knowing it could strand me in the rain at night somewhere.

Going to keep poking around but im wondering now if it was just a wet connection somewhere that has since dried out.
 

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"Water wet" will not blow a fuse. You have a harness that is rubbed and grounding out,as said, and now you have moved things,it is not. More than likely it is right there, near the oil sender. Found one one time, the harness clamp had rubbed into a wire,BUT, it had worked it's way right into the split/opening in the harness loom, was a bear to locate it, and feel confidant I found the problem.
 

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Discussion Starter · #14 ·
Yeah im going to have really go over the harness, starting at that location.

Because it starts and runs now and my wife needs to return her larents car soonish, this morning i thought what the heck ill drive the van today and see how it goes.

Didnt get more than a mile down the road and the engine began to "stutter" a little or hesitate. Have never experienced that with this van before. It wasnt really severe but enough to be noticeable. So i said nope and drove back home and im back to driving my wifes car until i get the time to figure it out.

I swapped out the relay before i turned around and drove home because i had bought a new one, but that didnt make any difference with the stutter.

Ive been busy the past few weekends and will be this weekend but hopefully get a chance to give the wiring another go over.
 

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Discussion Starter · #15 ·
Automotive tire Gas Auto part Automotive wheel system Electrical wiring


This is where the bundle of wires was feeing the oil pressure switch and two other sensors I have not identified.

The corrogated plastic insulation was wore all the way through where it was touching the engine so im going to get some new insulation, BUT i have not bee able to find any exposed wire on any of those wires there or signs that the short was there. I need to get some isypropil alcohol or something and clean each wire really good and inspect 1 by 1 with a magnigfying glass to verify the short is not here before closing up again...

I started the van and wiggled every bit of wire i could handle while it was running and could not get it to repeat any sign of shorting. At this point the only wires i have not done that with are the actual wires feeding back to fuel pump.

I think thats the next step i need to do is trace the wires from fuel pump all the way back and inspect those.
 

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Discussion Starter · #16 ·
Well i crawled underneath the van and inspected under there. Did see another spot the harness wiring is rotted right behind the valve cover on passenger side.... not even sure how i would go about fixing that one...

I couldnt even see this from above, had to wedge myself under transmission exaust on passenger side to spot it. Its right between the floor where the engine cover goes and engine and looks like somebody did something to a wire there in the past, can see in pic...

Heres a pic:
Automotive tire Human body Tread Jaw Synthetic rubber


I inspected the wires next to oil pressure switch, didnt find any evidence of break or short. Cleaned them off and put a new corrugated insulation there.

Did another test wiggling every bit of wiring harness i could get my hands on while it was running and could not get it to do anything funny. It idles fine, nothing out of the ordinary.

Took it for a test drive and it drove normal until i got on highway then it did the hesitation sputtering thing again while accelerating.

Is there any chance the fuel pump is going out and that caused the fuse to blow?

At this point i dont know what to think, but i have 2 ideas:
  1. Before this all started i ran it low on gas. Maybe the pump sucked up some crud and the sputtering im experiencing now is a clogged fuel filter.
  2. Maybe the fuel pump is on its way out explaining the blown fuse and also the sputtering its having now.
Im kinda at my wits end, dont want to throw a fuel pump in it if thats not the issue but its obviously not shorting out right now because i havent been able to get it to blow a fuse since i got it towed.

On another note while i was working on the wiring at the back of the engine there i pulled the distributer cap just to inspect amd there was a bit of corrosion in there and the points or whatever the rotor passes to distribute spark to plug wires each had some crap on them so i cleaned them off and wiped with 90% isypropyl alcohol and seems like it idles a little smoother now. Could just be my imagination though.
 

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Discussion Starter · #17 ·
Wife and i drove 30 miles round trip to visit a friend. Took the van to see how its working. Drove perfect. No sputtering or hesitation. As good as ever.

We were at our friends for about 2 hours. When we left it fired right up, drove home perfectly. Was just pulling into the spot i park on the street in front of house, put it in reverse to back closer to curb and it died. Wont start, had to push it the rest of the way. Quickely checked all the fuses, none "look" blown, will have to test with meter to verify.

Pretty obvious miracle it died right in front of my house and not on the highway, will accept that one. 😂

Any ideas? Is this still sounding like the fuel pump is going out, or maybe just went out?
 

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Doubt it is fuel pump. They don't blow a fuse then "fix" themselves. Still say you have a wiring problem. Engine moves one way when accelerating forward, another way when reversing.
Blow enough fuses without fixing a problem, then sometimes the next thing inline goes bad, IE the ECM.
 
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