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Discussion Starter · #121 ·
Getting back to your last video & relating that to my last post, I believe you said that your fuel pump relay was clicking. So going back to that relay tutorial, that a clicking relay could mean: 1) a bad relay, 2) bad constant ground for relay, or 3) bad quality of power to the switched side of the realy (which could be a result of bad wiring, or bad component that controls relay (meaning fuel pump itself or PCM).

Looking at the schematic (that I have) for the fuel pump system, it is wayyyyy simpler than the schematic for the engine control system. Starting at your fuel pump & going backwards, it connects to your PCM via the fuel pump relay, a 20A fuse & a 10A fuse. According to the schematic I am looking at, that all you've got: a relay, 2 fuses, & the PCM.

See where I am going with that?
Been sitting overnight. Cranks, won't start. No codes. No clicking. Just cranks and doesn't start. If the fuel pump portion of the PCM circuitry was failing, it seems to have failed for the last time, I'm guessing.
 

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so, when the engine dies, it's because it's no longer getting fuel. Then it won't start because the fuel pump is locked out. Which makes it sound like it's not getting gas when cranking, which is the reason I replaced the fuel pump in the first place. Then when it dies, I put the key to on, the fuel pump relay ( and others ) are clicking, because the PCM connected to them is not working correctly.
Right.
So where I was going with my last post to this thread was that the two relays which appear to be clicking are the ASD & fuel pump relay and they are both controlled by the PCM.
So when it is is the crank-but-won't-start-it-only-clicks mode, not only is it not getting fuel to the rail (fuel pump relay) but it isn't getting a signal to the coils (meaning nothing to the spark plugs) and the injectors are not getting power (ASD relay).
All this, & what we have discussed before in this thread, make me think your PCM has failed in (probably multiple ways).

Regardless of whether you elect to send yours out for repair or you buy a reman, remember to unhook the negative battery cable before you install the PCM.
 

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Discussion Starter · #123 ·
Right.
So where I was going with my last post to this thread was that the two relays which appear to be clicking are the ASD & fuel pump relay and they are both controlled by the PCM.
So when it is is the crank-but-won't-start-it-only-clicks mode, not only is it not getting fuel to the rail (fuel pump relay) but it isn't getting a signal to the coils (meaning nothing to the spark plugs) and the injectors are not getting power (ASD relay).
All this, & what we have discussed before in this thread, make me think your PCM has failed in (probably multiple ways).

Regardless of whether you elect to send yours out for repair or you buy a reman, remember to unhook the negative battery cable before you install the PCM.
well that makes sense, especially the part about the spark plugs. I could swear I smell gas/uncombusted fuel when I'm cranking/not starting. If it's injecting, but no spark, that could be the entire problem, or a part of it at least. And then there's all the other codes ( transmission, cam, radiator, etc )
 

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Just a quick review related to some of what we've discussed:
as I understand it, the ASD/automatic shut down relay (I believe labeled as "ENG" in the under hood electrical box) is controlled (switched on & off) by the PCM.
When the engine is starting/running, voltage goes through the ASD relay to provide battery voltage to the fuel injectors and to the coil(s).
At the same time this is happening, the PCM also needs to be sending a (trigger) signal to the coils (in a 4.7, coils is plural).
Instead of a distributor, the 4.7 has one coil for each plug ("coil on plug"); after the coil(s) receive a signal (in sequence) from the PCM, the coil that receives the signal sends a stepped up voltage to the spark plug via the plug wire. (So to get spark to the plug, the coil that fires the plug needs battery voltage via the ASD relay AND a signal from the PCM.)
(And, as previously discussed, in order to provide that trigger signal to the coil(s) the PCM MUST get a valid signal from the cam & crank pos sensors.)

Since voltage has to go through the ASD relay to get to the coil & the injectors, if that was one of the relays that was switching on & off, there should not have been any fuel going into the cylinders.

Looking at the "fuel pump system schematic", it is not directly tied to the "engine control system"; however, the relay that voltage goes through to get to the fuel pump is also controlled by the PCM. Meaning that when you were in the crank-but-only-clicks mode, if the fuel pump relay was one of the relays clicking (switching on & off) you were not getting power to the pump -- ergo, no pressure at the fuel rail.

We discussed that code for your electric rad fan; that circuit looks quite similar to "fuel pump system" circuit -- relatively simple -- power getting to the fan via two fuses & a relay. Although that relay is also controlled by the PCM, that circuit appears to have no direct tie in with the "engine control system" or the "fuel pump system." But, if the PCM was failing to energize that relay also, that may have also been one of the relays that was clicking and the code. However, not to be overly redundant, except for the fact that the fan relay is directly controlled by the PCM (as are the fuel pump & ASD relay) they don't share any other tie in (that I can see) & should have had no bearing, whatsoever, on power getting to your coils, injectors & fuel pump (which is basically what your engine needs to run).
 

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Do "one more thing" . . . all that stuff you were disconnecting & reconnecting with the battery connected may have conceivably blown a fuse or more than one.

Go through them all again (in both of your fuse boxes) one more time with an ohm-meter. Specifically I am thinking about what looks like possibly 3 fuses that are in the circuit with the ASD relay and the 2 fuses that it looks like are in the circuit for the fuel pump system.

There may be more but those are just what jump out at me.

I am not saying that this will "fix" your issue, but assuming a fuse in the right location was blown, that would make the relay in that circuit stop clicking.

And if you did install another PCM with one or more of those fuses blown, you still wouldn't start.
 

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Discussion Starter · #126 ·
Just a quick review related to some of what we've discussed:
as I understand it, the ASD/automatic shut down relay (I believe labeled as "ENG" in the under hood electrical box) is controlled (switched on & off) by the PCM.
When the engine is starting/running, voltage goes through the ASD relay to provide battery voltage to the fuel injectors and to the coil(s).
At the same time this is happening, the PCM also needs to be sending a (trigger) signal to the coils (in a 4.7, coils is plural).
Instead of a distributor, the 4.7 has one coil for each plug ("coil on plug"); after the coil(s) receive a signal (in sequence) from the PCM, the coil that receives the signal sends a stepped up current to the spark plug via the plug wire. (So to get spark to the plug, the coil that fires the plug needs battery voltage via the ASD relay AND a signal from the PCM.)
(And, as previously discussed, in order to provide that trigger signal to the coil(s) the PCM MUST get a valid signal from the cam & crank pos sensors.)

Since voltage has to go through the ASD relay to get to the coil & the injectors, if that was one of the relays that was switching on & off, there should not have been any fuel going into the cylinders.

Looking at the "fuel pump system schematic", it is not directly tied to the "engine control system"; however, the relay that voltage goes through to get to the fuel pump is also controlled by the PCM. Meaning that when you were in the crank-but-only-clicks mode, if the fuel pump relay was one of the relays clicking (switching on & off) you were not getting power to the pump -- ergo, no pressure at the fuel rail.

We discussed that code for your electric rad fan; that circuit looks quite similar to "fuel pump system" circuit -- relatively simple -- power getting to the fan via two fuses & a relay. Although that relay is also controlled by the PCM, that circuit appears to have no direct tie in with the "engine control system" or the "fuel pump system." But, if the PCM was failing to energize that relay also, that may have also been one of the relays that was clicking and the code. However, not to be overly redundant, except for the fact that the fan relay is directly controlled by the PCM (as are the fuel pump & ASD relay) they don't share any other tie in (that I can see) & should have had no bearing, whatsoever, on power getting to your coils, injectors & fuel pump (which is basically what your engine needs to run).
Right. I get that about the radiator fan. I'm just saying, a bad PCM, could be throwing codes that are a) not valid at all, b) about multiple things completely unrelated to the no start issue, as well as throwing c) valid codes about some things that are related and d) not throwing codes that it should be. Since it is such a high level component involved in so much. It needs to be replaced with a known good one, so that I can tackle anything that remains ( if anything )
 

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We are cross posting!
Make sure to read that post I just sent you about checking your fuses once more.

Yeah, the rad fan is not big on my list right now.
But what I see as relevant is this:
you think that this is one of the relays clicking
and what it has in common with the other relays that you think are clicking (fuel pump & ASD relays) is that it is controlled directly by the PCM.
(Kind of pointing us at the PCM as the issue.)
 

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I'm thinking PCM, and sounds like you are. Then I read this


Basics: Is it the Elec. Motor, Wiring, Fuse, Relay or...

and he replaced his PCM
. . . and . . . I don't know if you followed the subthread on this one, but it leads to this, which is interesting . . . .

 

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Discussion Starter · #129 ·
. . . and . . . I don't know if you followed the subthread on this one, but it leads to this, which is interesting . . . .

Ugh, well, I guess I can clean the connectors. I haven't ordered the PCM yet, I'm dollar challenged right now
 

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Ugh, well, I guess I can clean the connectors. I haven't ordered the PCM yet, I'm dollar challenged right now
I got back to that electric-fan/PCM thread that you posted & I followed it to that one I just posted.
I don't have high hopes for that, in your case, but when I am working on my own stuff I like to consider everything, & if it's cheap or free & not particularly difficult, I usually try it.

Someone posted a topic a few days or so ago related to a Dak PCM he sent out for repair a couple of years back, and he typed, and I quote, "Purchased a plug play from Flagship 1" which he states failed after a week. I have read a bunch of weird stuff related to Dak PCMs, but now I am starting to wonder if oxidation on the pins of the connectors might account for a lot of it.

I am definitely keeping that in mind for my own purposes, & I might just go out & clean my connectors with contact-cleaner & put some dielectric grease on them.

I might.
 

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Discussion Starter · #133 ·
disconnected battery, disconnected pcm plugs. The pins look nice and shiny. Blasted them anyway. Reconnected everything.

Cranks, won't start. I don't think it's getting spark. I can smell gas. No more clicking, because I can't get to the "starts, idles, dies, clicks" state of things.
 

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disconnected battery, disconnected pcm plugs. The pins look nice and shiny. Blasted them anyway. Reconnected everything.

Cranks, won't start. I don't think it's getting spark. I can smell gas. No more clicking, because I can't get to the "starts, idles, dies, clicks" state of things.
I edited out this part of my very first responses to your post because I am not sure how the wire harness is set up on the 4.7 with its coil over plug.

BUT, if you have battery voltage at the coil(S) with the key in RUN position (that SHOULD be a green/orange wire) that means you have voltage through your ASD relay. (It is worth pointing out that after turning the key to RUN, you will only have volts here for about 2 seconds before the PCM deenergises the ASD relay -- meaning you need an assistant to help you perform this check or you need your volt meter hooked up & in a position that you can see it when you hit the key. When you crank the starter, if things are working as advertised, you would see battery voltage then, also.)

Then you would check for trigger voltage from the PCM to your coil(S). That SHOULD be a black/gray wire. You would use an inexpensive LED test light & back probe this wire & crank the engine. If you had trigger voltage, the light would flash. No trigger signal would mean the coils are not firing your plugs and would also mean: 1) either or both a bad cam & crankshaft pos sensor or bad wiring from either to the PCM. If both sensors and their respective circuits were good, that would point to the PCM.
 

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. . . so with what I just typed in mind . . .
I suppose it is possible
that the fact that you no longer hear any clicking means that:
now the ASD relay and the fuel pump relay are no longer switching on & off. They are only switching on.
Which would mean that your fuel pump is pressurizing the rail AND injectors are getting power which I guess would mean that you would be dumping fuel into your cylinders. (You could pull a plug out & see if it is wet.)
IF the PCM is not sending a trigger signal to your coils, however, you wouldn't be getting any action at the plugs.

I suppose all that is possible.
 
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