Hi - I've been lurking here for years and appreciate all the info - have the dl of the 2001 service manual and the 2nd gen part book. Didn't see a service manual specific for 1998
1998 3.9 Sport extended cab, automatic with about 150K
In short, I wonder if any of you can verify if the "splice 115" issue is relevant on a 1998? Dying while driving issue.
Symptoms -
Never dies while in the driveway running... could run for hours
Starts right up every time, runs like a champ.
Driving along, maybe come up to a light, slow down, speed up, or just cruising at 25, 40, or whatever and it dies, flat out, no lights on dash, no power, no anything. If I can throw it in park generally will restart right away, but usually am where I need to get to the side of the road, and then restart. Never had it happen at 60+mph because I don't take it on the freeway since I fear that it could die there too!
Here's the thing - after each thing I've tried to "fix it" -- it may drive fine for months, or days, or weeks before it does it again. And NO CODES - ever!
Have done a ton of stuff - replaced TPS, Camshaft sensor, ignition pickup, plug wires, coil, new battery, checked and cleaned the grounds, new relays (like for ASD), crankshaft sensor (which seemed to "fix it" for a few months and I thought I won the lottery) and a bunch of other stuff I'm not even remembering to list here.

Last two things I can think of - PCM - which I ordered from a place and I gotta call the guy, but when I put that "new one" in, the truck dies in the driveway in less than 15minutes. Tried it on and off 4 different times... it always dies. Put my original computer back in and it will run forever in the driveway again.

Sooooo besides being the PCM I know about the "splice 115" and haven't yet opened up the wiring. Would happily be a simple fix if that's it, but...
Can anyone here tell me if that problem (or even that splice - which I've not been able to find on a wiring diagram) is relevant to the 1998 Dakota?
Don't want to have to rip open my wiring and pull them apart looking, if that splice isn't there! Several places say "under" the main relay compartment on the driver side, but my harness bundle is between that relay box and the fender, so I wondered if they had changed or corrected this splice 115 issue before 1998?

Any additional info or things to try are welcome...

 

Isn't the splice issue specific to first gen Dakotas?

Basically, I think something is getting hot, and failing..... Intermittent problems are just so much fun....... Either that, or there is a 'questionable' connection somewhere...... Sometimes, it's the PCM itself..... These trucks really don't care much for aftermarket sensors in critical locations either... Crank sensor being right at the top of the list, but, given what you have experienced, I can't point at it, and say: There's your problem....... It's entirely possible that it isn't just ONE problem, but a few different ones, that present the same symptoms..... Ugh.

Do you have a scanner you can carry around with you for a while? If you do, leave it plugged in, and see if it loses communication when everything goes dark.

 

Agree with HeyYou... These kind of things can be tricky.

Do the gauges go to all zeroes when this happens? Or do they stay alive once the engine cuts?

Just a tip, when it dies, go to Neutral and try to restart if you can't easily get to a shoulder or are going to get ran over from behind.

I'd be curious if there are any pending codes stored in the modules....

I do have to throw an obligatory "what if" to the fuel pump, albeit highly unlikely. It would stumble then die, not just die flat. That sounds more like a loss of ASD relay (injector/coil/FP power). But you've already serviced that item.

 

Thx Hey You -

That's what I was hoping to verify about the splice thing -- Can someone tell me if that's ONLY a 1st gen Dakota thing? Or *might* it still be a / the problem on my `98?

Yeah, that's why I got the new PCM - I gotta call the place tomorrow - I was really thinking that was it, but the new one isn't working right. And I hear you about the "getting hot" failing thing, but it can happen around the corner from home in 10 min in the middle of winter or not happen after driving 60 miles in 90 degrees, so I'm thinking not moisture, heat expansion, etc. I really feel like it's something that tweaks while the truck is moving, like a loose connection *somewhere* or a tiny solder crack on the PCM board... or...?

I have heard how picky they are with aftermarket stuff. Especially the Crankshaft Position Sensor... I've gotta go back and look up where I bought that... maybe need to go straight to the dealer to get one. I've seen posts about the positioning being tricky, but there was no way to adjust it or anything on the one I have, just take out the old one and put in the new one.

Yep, have driven around with the scanner plugged in, but I'd really need to rig a holder for it, otherwise it's in my lap or underfoot. And of course because it may go days or weeks until it quits, it has *never* quit when I'm driving around with it. I'm sure that it would lose communication though, as all power is gone, just like you turned it off - no gauges, no odometer, and no codes afterward.

Thx for your help -- and if you think of anything else or can verify the thing about whether the splice *is* limited to 1st Gen, that would be great.

 

Thx MagnetHead -

See my last reply to HeyYou also...
Yep, gauges all drop to nothing, no odometer, nothing... just like you turned off the truck.

And yes, - thanks for pointing that out -- I have also put into neutral to restart too, but usually trying to get to the side like I said!

And fuel pump always seems ok -- so no, I've not tested at the rail etc, because it *never* dies in while running in the driveway anyway, so I know it has fuel.

About the ASD relay - that's still just the little relay in the underhood fuse box, right? There's not another ASD gadget somewhere... I don't think there's an inertia switch somewhere on this truck??? So the if that's the only ASD thing -- I just did the ASD underhood relay this weekend, and no it hasn't died yet.

Just was trying to figure out if I need to go sort thru that wiring while I'm at it!

It's just a bummer that every thing I've changed seems to "work" until it dies again. No great assurance that it won' quit on me again, and I love my truck!

Any further wise words appreciated... and anyone else with a Gen 2 Dakota who had this intermittent dying thing... would love to hear what worked for you!

 

I can tell you with knowledge that the 3.9 hates crank position sensors. I fought a misfire forever, especially above 3000 RPM, until I put a dealer sensor in it. When I did the transmission swap, I discovered why.

On a V8, there are 8 "windows" in the flexplate that are 5 degrees wide. So the PCM sees 40 degrees of closed, 5 degrees open, 40 degrees closed, 5 degrees open, ect ... while using the cam position sensor "Injector Sync" to do other calculations.

On the V6, there are 9 windows. Why, I have no idea. I couldn't figure it out. But of the 6 "positions", three are single 5 degree windows, while the other 3 are a 5 degree window, 5 degree closed, 5 degree window. What happens with the parts store sensors are that they react slower, and they see those double-windows as a single 15-degree long window, especially at high RPM. Yea....that pisses off the PCM a little.

Yes, there is only the one ASD relay. It is controlled by the PCM, and feeds power to the coil, fuel injectors, and the fuel pump relay. *HOWEVER*, if it shuts off, the dash will stay on. So thereby, we know that's not your problem.

So here is my opinion. For you to lose all cluster, the radio, and engine all at once...there is only one sub-system which controls all three.

The electrical ignition switch located on the steering column, behind the lower dash bezel. It's very much possible that the contacts have gotten worn out after 21 years and 150,000 miles. My 3.9 is an 01 with 180,000 (or something like that, it's pretty much irrelevant at this stage of the build) and I've not replaced the switch on mine, but I know it will happen in due time.

 

I agree w magnet head on ignition switch.

I had changed mine out due to copper contacts being bad an that fixed it.