The signal ground is also delivered by the pcm from pin 94. I would suggest checking resistance to ground between the 85 pin of the FPR when first keyed on. What voltage do you have at the 86 pin KOEO? It should read B+ as long as the key is on. It's the wire that's fed straight from the PCM relay and shared with a handful of other critical components, the IPR being one of them.

 

Finally got back to it this past weekend, had a bunch of travel for work and just left it parked in the driveway. Having really no idea what was happening, figured I'd do a little maintenance. Checked the oil for the proper level and changed / cleaned the fuel filter and Racor strainer under the cab, to ensure proper flow which was good. When that didn't get me anywhere, I went at it with a multimeter checking fuses. Should've started there. As shown in the photos provided by Jeff above, the 20amp #4 fuse in the under hood panel was blown. As I don't have any fuses that small, I pulled a random 20amp fuse from the under panel box (#3 as it was the easiest to grab), plugged it in and it started.

No idea what these fuses are for, no idea what is no longer working from the missing #3 fuse, nor do I really care at the moment. Still annoyed. I seem to have lost my service manual pdf's, and my physical manuals are packed away in some box deep in the basement.

So if anyone might be able to explain what happened, this could be a good lesson should anyone else have this issue. Pulling the radio to inspect the relay that was clicking ended up becoming it's own problem, as the aftermarket plastic kit that held the replacement radio broke and now I can't securely reinstall that crappy old radio I had. Sure, I have been wanting one of those fancy big screen Android radios, but is this really the motivation I needed for that project??

Thanks for the help guys.
Tom

 

That doesn't make a lot of sense. That fuse is for trailer light. I pulled that completely out of my e99 like 2 years ago while chasing a random no start and never put it back. It's only for trailer hookup stuff. Unless it's some how shorted to something actually important I got nothing.

 

Yeah, I just saw that in a fuse chart in another thread and had the same thought. I have the optional trailer hookup with the brake controller, but I disconnected the brake controller years ago so it should be an open circuit anyway. I have an e99, Feb 1998 build, any chance that makes a difference and this fuse is related to something else? Not sure if I want to remove the fuse and see if it still starts, I really dislike electrical faults like this ...

 

I would. Honestly it's almost more likely you wiggled something that was loose and that "fixed" it that that trailer back up lights fuse did it, but I'd want to know.

 

Yeah I'm saying bad connection somewhere in the fuse box also. I would wiggle things around, fuses, relays, box, wires. Gentle like one by one. Something was a problem and it probably didn't go anywhere. If you still don't find it you know where to start looking if you have a future problem

 

But it's winter now, and cold out. And raining. Why doesn't this crap happen in the summer?

 

Because the Truck Gods have a twisted sense of humor. How long since you paid homage? I hear they're fond of busted knuckles and $$.

 

Actually, it's been quite awhile. I only use it when working on the house and need stuff. I've been thinking about putting classic tags on it as the registration is cheaper and wouldn't require annual inspections.

 

In my case, the better question is typically “why do I always put the job off until times like this?”

 

So as a final follow-up to this thread, I *think* I know the answer. It was a very intermittent issue and looking back seemed to occur only after a recent drive. I never solved it at the time, just kinda gave up until the weather changed and I was able to complete some other much needed and greatly deferred maintenance, i.e. that old water pump - started in May 2017, and completed last month.

So while cleaning up the front of the engine when the water pump was out, I broke out the electrical connector spray and started hitting all of those connections under the hood. Since the water pump at the end of its life was spraying water all over the place, this cleanup led to pulling stuff off the top of the engine and getting to those connections up there. That big plug for the injectors was completely fouled up, and those little rubber or whatever they're made of environmental seals in most of the connectors are shot. After cleaning all the connections, she runs better now than she has in a long time.

So I have a new question, is there a source for just the seals in any of these connections?

 

been in electronics since 1958, and I never saw a replacement seal for a special connector like our trucks use.

I have to replace the connector, splice into the harness, or replace the harness.

 

Some of them are available from Riffraff. Eswift sent me a link to the IPR seal (which I couldn’t find). I still need to order this 🤦‍♂️ as I’ve been waiting for “an order” to save on shipping. You should give them a call to check availability if there are others you need.

https://www.riffraffdiesel.com/injec...lacement-seal/

 

Thought it was solved, but not I guess not. After replacing the water pump and cleaning every electrical connector I could reach under the hood, it's been running fine. Today, it's back to the same no start symptom in post 1 after sitting for about a week. Two things have happened since it last ran. The shifter handle broke off in my hand just as I turned up my street, a handy pair of vise grips got me home and backed into the driveway. And while waiting for the new shifter to arrive this morning I power washed the passenger side last Friday. Drivers side is always parked against the fence to save room.

Anyway, just installed the new shifter, and the no start is back. I can upload a video of the crank, but it seems fairly normal to me, aside from it's not actually starting. I have a denso starter so it spins quickly, but there's no smoke so no fuel, just like before. I noticed that while cranking, even though it's normal sounding, the battery and fuel level indications go low, oil pressure goes up and tach is maybe around 400 or so. With a meter on it, battery voltage drops to around 8Vdc while cranking, even with a cheapo 50amp charger / starter connected. I again went through all of the fuses and relays and cleaned them, and the battery terminals are still tight (I didn't touch them yet as I didn't feel like breaking out all the tools I JUST PUT AWAY! Battery voltage is 12.4Vdc not cranking.

Possible my batteries are shot? These are standard batteries, don't remember when I got them so they're likely several years old.

 

If the batteries are dropping that low while cranking it's never going to start. If they drop below 10v the PCM and modules cut in and out because it's below their minimum voltage requirement to operate. Sounds like you've got a parasitic draw. Don't worry they'll give you a shot and then some ointment to take home, should be fine in a week or so. Seriously though you've got a parasitic draw here's a link that explains how to test for it and find the source.

https://www.innova.com/blogs/fix-adv...parasitic-draw