04 dakota 3.7 strange problem with random shutoff

I did go through a period with my '03 Dak with 60+k miles (at the time) when it would intermittently shut down.
No CEL.

But how it differed from yours was:
sometimes it didn't want to start back up (& fortunately for me these episodes happened in my driveway)
and
intermittent devolved to terminal, &, unlike yours, this took way less than a year.

The troubleshooting sequence that I followed pointed at the PCM so I did send it to a facility that diagnosed it & repaired it.

As I see it, the biggest obstacle to troubleshooting yours is the fact that yours is still intermittent, & I have always found it hard to fix something when it's not acting like it's broke.

As far as the crank position sensor (ckp), that was one of the parts I threw at mine in the intermittent stage.
I also threw a cam position sensor (cmp) at mine when it was intermittent.
When it became terminal I worked on the assumption that both the cmp & ckp I had installed were good parts, so I bypassed the troubleshooting step that called for checking both.
(I would also think that if the shutdowns were related to either the ckp or cmp that you would get a CEL with a specific code pointing to either.)

I am not sure how the input speed sensor on the transmission would cause your intermittent shut down (I can see the ABS & BRAKE light due to that), but I don't claim to be an expert on the subject, so maybe I've missed something on that.

If you don't mind the shotgun method, I would start with (in this order)
the ASD (aka ENG) relay because voltage for the coils & injectors goes through that relay (although I don't know if relays often fail intermittently)

and then the CKP & CMP as the PCM needs a good signal from both to send a trigger signal to the coils and, I believe, to energize the fuel pump relay, & if I am understanding it correctly if the PCM doesn't get those signals it will also de-energize the ASD relay. (& I suppose, on that note, you could throw a new fuel pump relay at it, although what I typed about relays failing intermittently).

Good luck with this.

immattj said:

I did go through a period with my '03 Dak with 60+k miles where it would intermittently shut down.
No CEL.

But where it differed from yours was:
sometimes it didn't want to start back up (& fortunately for me these episodes happened in my driveway)
and
intermittent devolved to terminal, &, unlike yours, this took way less than a year.

The troubleshooting sequence that I followed pointed at the PCM so I did send it to a facility that diagnosed it & repaired it.

As I see it, the biggest obstacle to troubleshooting yours is the fact that yours is still intermittent, & I have always found it hard to fix something when it's not acting like it's broke.

As far as the crank position sensor (ckp), that was one of the parts I threw at mine in the intermittent stage.
I also threw a cam position sensor (cmp) at mine when it was intermittent.
When it became terminal I worked on the assumption that both the cmp & ckp I had installed were good parts, so I bypassed the troubleshooting step that called for checking both.
(I would also think that if the shutdowns were related to either the ckp or cmp that you would get a CEL with a specific code pointing to either.)

I am not sure how the input speed sensor on the transmission would cause your intermittent shut down (I can see the ABS & BRAKE light due to that), but I don't claim to be an expert on the subject, so maybe I've missed something on that.

If you don't mind the shotgun method, I would start with (in this order)
the ASD (aka ENG) relay because voltage for the coils & injectors goes through that relay (although I don't know if relays often fail intermittently)

and then the CKP & CMP as the PCM needs a good signal from both to send a trigger signal to the coils and, I believe, to energize the fuel pump relay, & if I am understanding it correctly if the PCM doesn't get those signals it will also de-energize the ASD relay. (& I suppose, on that note, you could throw a new fuel pump relay at it, although what I typed about relays failing intermittently).

Good luck with this.

Click to expand...

I'm sorry I realized I actually forgot something, the reason I suspect the ISS us because sometimes I also have problems up shifting into high gear when my speed is under 60mph. If I try to push it it will just get stuck in a loop of trying to shift and failing BUT if I happen to get a boost of speed from going downhill and make it above 60mph it will shift successfully. My thought process that links the two problems (both are intermittent and happen for no obvious reason) is that if the transmission is not getting a signal from a speed sensor, it won't know which gear to shift into or maybe try to shift without actuating the clutch and it causes the engine to stall while driving. And since it's a transmission issue that explains why there's no CEL. I'm not sure if this is really a possibility as I just don't have enough experience fixing mechanical issues as I'm more of an electrical tech. Both problems started happening pretty much around the same time so it makes me thing theres a common cause.

DanZ said:

Also because the engine will crank right back up with no problem after it dies, that makes me thing it's nothing to do with anything that would keep the engine from starting up if it went bad. The speed sensor isn't involved in starting the engine or keeping it running so it kind of makes sense to me at least

Click to expand...

I agree with you that the speed sensor isn't involved in starting the engine or keeping it running.
Which is why I don't see it being the reason you are intermittently shutting down.
The way I see it, your intermittent shutdowns have to be due to either a momentary interruption in fuel through the injectors or fuel pressure or a momentary interruption somewhere in the chain that ends with voltage at your spark plugs. 'Momentary' being the operative word.

When your transmission intermittently fails to upshift properly, does this seem to happen in the time frame when your engine may have an intermittent shutdown?
I am out of my small sphere of familiarity with both the 3.7 (which I understand is electronically more complex as far as its engine controls go) and transmissions (& I guess yours would have a 45RFE or a 545RFE? which I am REALLY unfamiliar with) but it would have a TCM which would generate certain codes. I recall reading a thread & I think it was OldMarine who said something about certain years having the TCM integrated as part of the PCM & certain years having it as a separate module, but I really don't remember.

Regardless, I could be wrong (I often am) but I just don't see the ISS as having anything to do with your intermittent shutdowns.

I'll do some more reading.

DanZ said:

What would be helpful to me is if someone had a list of everything that could trigger the ASD relay and that might give me some clues on where to look for a problem

Click to expand...

I believe ASD (which also goes by 'ENG') stands for 'automatic shut down' & the intention was to turn fuel off at the injectors in event of a wreck. I think that there is a better explanation than that, but basically, when the engine stops turning, the crank & cam position sensors (ckp & cmp) no longer have rotating parts to sense & therefore they send no signal to the PCM & when the PCM is not receiving signals from both the ckp & cmp the PCM de-energizes the ASD relay & voltage is lost to the ignition coil & the injectors (in this situation I believe the PCM also de-energizes the fuel pump relay). For the crank & cam position sensors (& other sensors as well) to function, they get 5v from the PCM to power them.

So the control for the ASD relay is the PCM & I think that there should also be a fuse in the PDC (under the hood) in the circuit. Could a ASD relay just start to fail intermittently & randomly? Since a relay is basically a switch with contacts & I guess a coil inside to excite them, I guess it would be theoretically possible for that to happen.

. . . I was thinking about another thread that I had been following, & the OP (who has a 4.7) on that thread recently encountered a shutdown issue which involved a code for the ASD relay. Not that I think you have the same problem, but he did get a reply from OldMarine which was a great explanation of the ASD relay. I'll copy the answer & post it below as it may be helpful for your understanding:

OldMarine wrote:
"The ASD relay is controlled by the PCM. The ASD relay provides 12 volts to the coils and the fuel injectors. The PCM controls the individual coils and fuel injectors by providing a ground as necessary. The PCM monitors when the ASD relay is providing power to the coils and injectors with a feedback loop. The wires providing power to the coils and injectors are colored dark green with an orange tracer. The feedback wire is also colored dark green with an orange tracer and it goes back to the PCM at pin 12 on connector 3. There is an additional component in this network of wires -- a capacitor, apparently for noise suppression for the radio.

Because the engine quit suddenly, I would suspect (based on the P1389 code) that the wire feeding back to the PCM suddenly lost power -- it was either broken, or possibly all the coils and injectors lost power at that same time (ASD relay went bad?). But on a hunch, I'm thinking the capacitor may have failed. In the old points/condenser (capacitor) ignition systems, when the condenser went bad, the coil would not provide spark. This is not the purpose of this capacitor, but the effect can be the same -- no power. I have no idea where it is located; the FSM just says on the left side of the engine. But look for a small component with a single dark green/orange wire going to it. The wiring diagram indicates it is grounded by its mounting bracket. If it failed, it may be partially grounding the coil/injector power system. Disconnect the wire, but don't let it touch any ground. Then see if the engine will start.

If the capacitor is not the problem, and the ASD relay checks out okay, you'll have to trace and troubleshoot the wires (dark green/orange) in the coil/injector power system."

That's all good information and I thank you for taking the time to post that. What sucks is with the problem mostly happening while driving I can't really test what is happening without some sort of signal data logger that could record the signal coming from the sensors to see if anything drops out
Also relays can fail in a few ways, if its the ASD losing power then there could be a few reasons for that to happen, corrosion at the terminal, broken wire that is not completely cut but was only pinched so the jacket is still together but the wire inside is only making temporary contact. I see this all the time with truck liftgates when they pinch the remote wire between the truck and gate. Another possibility might be the metal strips inside the relay are losing their springiness from cycles of hot and cold. I just fixed a friend's trailblazer that had a similar problem with the contacts inside the key switch which is a very poor design and the only thing that keeps the contacts closed is the spring of the metal and the action of turning the key actually opens the contacts instead of closing them mechanically.

Lots of possibilities still but I think I have a few new ideas of where to look