Still Flakey Problem

crossposted back to rec.autos.tech, where the problem first appeared..

ground path or command line?..

Ground path for the high speed relay is through pin 10 of the VLCM.. the only input I see on the pinout for the VLCM is for fuel pump input, so I suspect that all the rest (cooling fan motors, high speed fuel pump relay and AC clutch are controlled through the data bus.. which looks to be pin 21 (SCP+) and pin 23 (SCP-).

One of the tests a scan tool would allow you to do is command fuel pump on.. if you commanded fuel pump on and it didn't turn on you could probe fuel pump input and tell if the signal is lost inside the PCM, or if the VLCM is receiving a signal, but not activating the pump.

Regards,

Jim

Hey, Jim.

This has become comical. Since we really aren't sure of what signal is supposed to be where and when.

I checked the pin 80 and it starts out low/grounded and stays that way.

You see, we don't know what conditions have to be met for the VLCM to get the signals it requires at the time they are required. The fuel-pump sends back its pressure signal to the PCM and we don't know how the software is handling that info in order to tell the rest of the associated hardware what to do.

In my way of thinking, it seems to be the most logical approach to get the fuel-pump relay going. Since we are guessing in thinking that the relay is controlled via the data buss, and we DO KNOW that the relay is controlled by an mosfet, we can only guess at the rest.

Yes, this is being over-thought but, since there is a dearth of information, I/we are left at trying to hone out a logical approach to solving the problem. To me, it is fun. It is also perplexing.

Digressing to the pin 80/12 problem. As I said, we don't know what conditions have to be met for the low-speed fuel-pump supply to turn on. I think we know that pin 40 of the PCM supplys 12 volts to the f.p.

The driver gets in, turns on the ignition which should turn on the f.p. relay and that is just hot happening. There has to be some information out there somewhere that tells more about this fault.

Thanks

Cass

I am running an experiment re. cross-posting and I didn't recall where your post orginated

information,

Excuse me for laughing cass, but this whole thing has been really pretty amusing to me. The funny thing is that the information is available, hell I'm guessing there are at least a half dozen people on this newsgroup who know exactly what your problem is but like me they remember you. Looking at the questions you are asking I can see that you are thinking powertrain control module, variable control relay module or a wiring problem. Well, the problem "could" be one of those items, it could also be a problem on one of the other processors using the data bus such as passive restraints, air suspension, climate control and about a half dozen others. For your information the PCM commands the fuel pump on through a digital signal down the data bus to the VCRM. Any disruption of that signal causes problems. You are about to find out why used Lincolns are fairly cheap....lol!!!!!! Bob

Bob,

I see that you are still foaming at the mouth because I spoke the truth and said that there are a lot of crooks in this business. I think it is pretty funny how you took that personally. I don't wonder why.

Now, you guess that there are about 6 people on here who know exactly what the problem is with this Lincoln and won't say so. I think you are dreaming. I don't think one person on here KNOWS what the problem is.

I see that some have guessed. One or two seem to be fairly knowledgeable. Many have pointed out what the book already points out. NONE HAVE GOTTEN IT. However, I will say that I am most appreciative of those who really have tried.

Now, you come along and demonstrate your lack of understanding of the problem and proffer a wild guess that it could be a lot of things. Yes, it could be several things, Bob. However, you and others have demonstrated that they don't know exactly where the fault lies. Either you haven't been keeping up with what has already been said or, you didn't understand it and pull out a wild guess that 'it' could be a lot of things. What a hoot!

Cass

Uhh,make it seven. You are such a fool cass,as much as you despise Bob,well,you really should be thanking him.He just pointed you and your helper in a direction that will solve your problem. No wonder everyone hates you.

JT

Turner:

You seem to forget that Bob 'started up' with me, for no other reason than that I said that there are a lot of crooks in this business. He went foamy at the mouth and truly showed his ignorance. I simply don't take abuse without trying to give it back tenfold as to do otherwise, only encourages a coward/bully to pounce on the next guy for no reason.

Can you back up your claims that S.O.B. (sorry old Bob) pointed me in a direction that would solve my problem? NO, YOU CANNOT. He made some wild claim that was so general and DID NOT APPLY so as to be funny.

Let's remember the facts in this latest round of posts; I asked if there were any REAL experts on here that could assist in a problem about a fuel-pump not turning on. I purposely made the question into a challenge so as to frighten off the ones who would say 'check the fuse', 'bad fuel-pump', 'empty tank, etc.'. THAT IS ALL THAT I DID. Now, why would you be insane with anger over that?

Also, I don't have an assistant. Where did you get that?

Cass

Everyone hates me? Do we know the same people?

Not at all! I find it very entertaining. You've been testing this and testing that.....scratching your ass and picking your nose.... and yet you are still riding the bus because your trusty Mark VIII won't run. And the funniest part is that you aren't any closer to a solution than when you first opened the hood. Maybe you should buy yourself a Yugo or something along those lines to drive in the meantime. I think a Yugo would fit your personality better than a Lincoln anyway. Bob

Bob:

You have absolutely no idea what the problem is with this car. You have proved it by saying, and I quote:

"the problem "could" be one of those items, it could also be a problem on one of the other processors using the data bus such as passive restraints, air suspension, climate control and about a half dozen others".

You see, Bob, you don't understand what a data buss and its associated protocol really is. If you had understood the earlier posts, you would have seen that you are flat wrong about suggesting that it is something else on the data buss.

Here is a direct challenge for you, Bob. I can guarantee that you will run from this question or try to obfuscate the question with some inane answer so as to prove to everyone that you are full of BULL.

Here is the question: How do you think another processor using the data buss can possibly be responsible for the fuel-pump not working? This really should be good. And, lest you think that I am fishing for an answer, just make your answer a general one saying exactly how A MODULE can be the culprit, in this case.

Bob, all you really want to do is to vent your anger and rage at the world for some unfathomable reason. You are a little man and little men try to drag others down to their level.

Intelligent and kind-hearted folks usually try to help others. You are not able to help so, you try to denigrate and hurl insults simply because I said there are crooks in this industry.

Cass

Maybe my information is better or there are other reasons, but this looks to me to be a fairly simple circuit..

This differs from when you said..

"On pin 80 of the PCM, I am getting an ~ 5volt level. Now, when I first turn the car to the run position, this applies operating voltage to the module/s and, for a second or so, it is low. Normally, one might think that is the low or ground signal that you say should appear on pin 80. However, I really doubt that it is a valid signal SINCE, it is going from off/low/ground to off/low/ground."

I'm not sure what you mean by it not being a valid signal though..

As mentioned, the low speed fuel pump relay is activated for a moment when the key is turned to the 'on' position, during cranking, and during engine run.

Huh?.. where is the pressure sensor?.. what circuit(s) does this all happen on?.. what pins are used at the PCM?

How many fuel pump relays are there?.. how are they controlled and when are they activated?.. It seems there might be a misunderstanding about the fuel pump relay circuits.

Here's what Ford says to troubleshoot this problem..

*Check for VPWR to VLCM Pin 16 *Check fuel pump circuit continuity *Check FP circuit for short to ground *Check VLCM FP circuit *Check PCM for short to GND *Check fuel pump (FP) circuit for short to ground 2 second prime when key turned on, on when engine cranking, on when engine running. Or, use a good scantool and command fuel pump on.

No. Here's what pin 40 is for.. (from one of my responses in rec.autos.tech, where this thread started)

"Fuel Pump Signal: Description and Operation

Purpose: The Fuel Pump Monitor (FPM) circuit is spliced into the Power-to-Pump circuit and is used by the PCM for diagnostic purposes.

Operation: The PCM sources a low current voltage down the FPM circuit. With the fuel pump Off, this voltage is pulled low by the path to ground supplied through the fuel pump. With the fuel pump Off and the FPM circuit low, the PCM can verify that the FPM circuit and the Power-to-Pump circuit are complete from the FPM splice through the fuel pump to ground.

This also confirms that the Power-to-Pump or FPM circuits are not shorted to power. With the fuel pump On, voltage is now being supplied from the Fuel Pump Relay to the Power-to-Pump and FPM circuits. With the fuel pump On and the FPM circuit high, the PCM can verify that the Power-to-Pump circuit from the Fuel Pump Relay to the FPM splice is complete. It can also verify that the fuel pump relay contacts are closed and there is a B+ supply to the Fuel Pump Relay."

Which FP relay?..

Key off.. PCM disconnected.. VLCM connected.. jump pin 12 of VLCM to ground.. key on.. DOES FUEL PUMP RUN? (this assumes that power and grounds have been checked)

If fuel pump runs, suspect PCM. If fuel pump does not run, suspect VLCM.

Try that and let us know what happened..

Regards,

Jim

Jim,

I do not recall whether the VLCM was connected when I said that pin 80 of the PCM began low and went to ~5 volts.

There is only ONE fuel-pump relay that I can find.

By Ford saying check the xxx or the yyy, that is easily said but they don't give information on what voltages and expected where and when.

I will try your suggestion about disconnecting the PCM and grounding pin 12 of the VLCM. I sure don't feel comfortable grounding a pin that I am not sure of what circuitry is connected to it. That is a good way to blow stuff.

Thanks

Cass

"Ca_s_s__ wrote

Go for it, Cass. This is exciting...let us know what (if any) components you happen to smoke. Geez, this newsgroup is boring and then you come along with your exciting diagnostics. And by doing something that you are uncomfortable with...well, that's just pushing the envelope. I tip my hat to you for taking the plunge.

Ian

Meanwhile I snicker in the background while the crowd chants go, go, go, go...... I think if grounding it doesn't work he should use a jumper wire (properly fused with a 30 amp CB) and jump it to B+. LMAO!!!! Bob

By the way cass, if you do happen to let the smoke out of any of those components you should send them to me. I've got an OTC smoke machine and for a small fee I can put the smoke back in.. You realize of course that putting the smoke back into electronic components is still in the experimental stages, in other words NO WARRANTY.

Bob:

Here is a novel idea: why don't you and I discuss the problem and leave personal dislikes of each other out of it?

I am sure that you are afraid to do that as you ran from my question to you about data busses. However, I will give you the chance to show your expertise by inviting you to calmly and methodically discuss the problem?

Up for it?

Cass

Ian,

Do you realize that there is a way to 'ground' a circuit and not take a chance of 'blowing it'? If so, I wonder if you would care to describe EXACTLY how that would be accomplished? Surely, you won't follow Bob Knutson when he turns and runs from a challenge, will you?

Cass

Sorry cass, but I just can't seem to come up with a single reason why I would care to help with your Lincoln. I did get a pretty good laugh out of the fact that you are desperate enough to ask me for help though. Trying to turn this into some kind of a personal challenge was really just too funny! Bob

That's what I suspected.. there are two. From what you've posted I think the one you've found is the stand-alone one.. that's the high speed relay. The low speed relay is inside the VLCM and is NOT controlled over the data bus. Check your wiring diagrams closely and re-read all I've posted..

The information I have does list voltages and the such.. but it's pretty basic stuff.. Check for VPWR to VLCM (was voltage greater than

10.5 volts?) Check FP circuit for short to power (Was voltage less than 1.0 volt?)

So is disconnecting parts of a circuit and then powering up the circuit.. like powering up the PCM with the VLCM disconnected. Bad mojo to mess around with stuff when you don't really understand what you're doing. Maybe it'll be ok, maybe the smoke will get out. Either know what's going on and have good diagnostic information (or reverse engineer), or be willing to buy parts.

My suggestion is Ford Diagnostic information.. straight from AllData.

Let us know what happens when you try that test..

Regards,

Jim

"Ca_s_s wrote

I believe that both Bob and I are up to the challenge....but I suspect it's not the same challenge that you are attempting to put before us.

Our challenge (if I might put words in Bob's mouth) is to read with great interest any of your posts and find whatever humor is possible in your diagnostic situations. Which isn't hard.

Ian

Bob,

EXACTLY! That is exactly what I said; you would turn and run from a challenge as you know very well that you would prove just how little that you know.

However, you stuck your nose into this just to stir up trouble and have done nothing but continue to stir trouble, as you always do.

Try to do something constructive for a change. It will do you a world of good.

Cass

Jim,

SUSPECTED? There is ONE relay. Only one! No more than one. I am talking about the relay associated with the fuel-pump.

Now, as I have said, there is an mosfet that drives the low-speed function of the fuel-pump. Re-read what I have said.

To get on the same page: you are saying that the high-speed function of the fuel-pump is controlled by the data buss of the VLCM, right?

It has been raining for several days so I haven't been able to do any further checks.

I have suspected that you have been jerking me around but wanted to make sure. Do you recall saying this:

"Key off.. PCM disconnected.. VLCM connected.. jump pin 12 of VLCM to ground.. key on.. DOES FUEL PUMP RUN? (this assumes that power and grounds have been checked)

If fuel pump runs, suspect PCM. If fuel pump does not run, suspect VLCM?

If you do, how can you turn around and say that it is bad 'mojo' to mess around with something when one doesn't know what they are doing and then, you advise to not do what you suggested in the first place.

I kept wondering why you couldn't answer a straight question and made this much, much more complicated that it really is. The proper information has simply not been presented in order to PROPERLY diagnose this problem.

If you are simply parroting all that Alldata says, then, they are not saying enough to diagnose this problem.

One could simply be a parts-changer and like a blind hog occasionally finding an acorn, eventually stumble across the defective part. Or, they could be a crook and put in stuff until they found the problem and leave the stuff in. Or, if someone did this for a living, they could ferret out source/s of complete information that would allow them to approach the problem intelligently and methodically.

I have the Helms/Ford Service Manuals for this vehicle except for the power-train. I doubt that there is any different information in that manual that would allow troubleshooting of this problem.

Cass

Cass