Ford: STILL FLAKEY PROBLEM

"Cass" <com> wrote in message news:<bk5qvc$7g8$alt.net>... 

Put down the voltmeter..
 

I think it's better for the PCM to sink rather than source.. with
your way, tell me what's happening to the PCM with 'that line shorted
to ground'..
 

grab your LED testlight...
 

Testlight clip to battery B+, probe pin 80. If testlight lights for a
second or two at key on, or lights up with engine cranking, your
problem lies elsewhere.

You could even probably get away with using a normal testlight if it
doesn't draw too much current.. the one I use draws about 0.04A. Best
not to use a Hi-Z meter for stuff like this.. save it for measuring
state-of-charge of the battery. Now, if your meter has a low-Z
setting, that might work.

If pin 80 lights the testlight, probe pin 7 of the VLCM (for a
positive voltage, but less than battery voltage), see if it lights. If
not, check for B+ on pin 6 of the VLCM.

Pin 7 is power to fuel pump, low speed. Pin 6 is B+ for fuel pump.
Pin 10 is high speed fuel pump relay output. (All on VLCM)

It should take all of 5 minutes to check to see if the problem lies
with the VLCM or elsewhere.. this does not sound like a difficult
problem to diagnose.

Regards,

Jim

Jim,

I don't use a test light for several reasons. One is that depending on the
light, the voltage could be marginal and give false indications. Some test
lights can destroy some electronic circuitry; not only due to excessive
current draw, but, in the case of filament lamps, inductive kick-back has
killed more than one chip. Rare, to be sure but it happens.


You ask the question as to what would happen to 'that line' on the PCM if
done my way. Well, if sourced current/voltage any competent engineer would
put current-limiting resistors in the line. Even better would be to use
opto-isolators with proper dampening for noise glitches falsely triggering
the device. So, you could short that line all day long for years and as
long as currrent limiting was designed in (simple) nothing would happen.

You say that it should be simple to trouble-shoot this circuit yet, the
problem remains. Can you tell me EXACTLY what level this pin 80 should be
in order to activate the fuel-pump, high-speed relay?

Guessing at this is going to take a chance of buying a module without
knowing that it is defective.

One MUST know what level the VLCM expects on its pin 12 and going to pin 80
on the PTM.

I think it is safe to assume that 12 volts appears on pin 40 of the PTM from
time to time when the computer says it is time to turn on the fuel pump for
another shot of fuel. Pin 10 of the VLCM is expecting to be low or grounded
in order to turn the fuel-pump on by applying full voltage to the pump. Pin
7 of the VLCM is probably pulse-width modulated signal applied when
fuel-pressure drops and sends that signal to the PTM.

As I have mentioned, I have verified that the battery voltage on the VLCM,
which is pin 6 for the fuel-pump but the other battery pins are okay, too.

Also, the state-of-charge of a lead-acid battery cannot be determined by
nothing but a voltmeter. But, let's leave that discussion for later.

This should be a very, very simple thing to diagnose ONLY IF and ONLY IF,
one knows for certain what level the VLCM is expecting from pin 80 of the
PTM.


Thanks

Cass





"Jim" <com> wrote in message
news:google.com... 
news:<bk5qvc$7g8$alt.net>... 
turn 
module/s 
the 
of 
let 
the 
the 
ground 
80 to 
provide 
could 

"Cass" <com> wrote in message news:<bk88nf$9gt$alt.net>... 

Yes, you have to be careful with a testlight and computer circuits
(that's why I spec'd an LED testlight), but, speaking from experience,
you'll burn yourself if all you use for automotive diangostic work is
a Hi-Z meter.. especially in situations where current has to flow.

 

More parts equals more cost.. manufacturer's will never go for that..
while some drivers in the ECM use current protection, much of the
stuff controlled by the computer (like injectors and ignition) are
ground side controlled.

 

Pin 80 has nothing to do with the high speed relay.. it's the ground
path for the low speed relay control side.
 

You're speaking in terms of logic circuits.. pin12/80 is the ground
path for the low speed fuel pump relay (even though it may not
technically be a mechanical relay). If you tie this circuit to ground
and you don't get anything out on pin 7 of the VLCM then you've found
your problem.

 

Nope.. wrong.
 

Pin 10 is the control line for the high speed fuel pump relay.. but
high speed is only activated under heavy load conditions.

 

Pin 7 is the power output for the low speed fuel pump.. it goes from
pin 7 through connector C122 through splice S254 through connector
C212 and ends at splice S254, which is the power feed to the fuel
pump. PWM?.. perhaps. Ford has done that on some other cars already.
 

Good.. always check power and grounds.
 

<grin>.. love to discuss this later.
 

It's a ground path and it has to sink current..

You are _WAY_ overthinking this circuit..

Regards,

Jim

Okay, Jim,

Well, are we going to assume that the VLCM grounds the high-speed pump relay
through the data bus?

Cass


"Jim" <com> wrote in message
news:google.com... 
news:<bk88nf$9gt$alt.net>... 
the 
test 
has 
if 
would 
triggering 
be 
80 
from 
for 
VLCM, 
too. 
IF, 
the 

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

"Cass" <com> wrote in message news:<bka7f3$3nb$alt.net>... 

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


"Jim" <com> wrote in message
news:google.com... 
news:<bka7f3$3nb$alt.net>... 
relay 

"C_a_s_s_no_DAMN_spam______" <com> wrote in message news:<bkdifg$dvr$alt.net>... 

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

On 23 Sep 2003 04:03:33 -0700, com (Jim) wrote:

[Cassfart deleted]
 
.... 

As you say, Jim, the whole Casstration story is in Google Groups at
http://groups.google.com/groups?as_usubject=casstration. Check it out.

In a nutshell, Roscoe St. John created this "Cass" persona in order to
disrupt -- hopefully destroy -- our newsgroup communities. Why he has
pursued his crusade for six years no one really knows; that is a
matter between Roscoe and Dr. Fellow Hoofers, his court appointed
psychiatrist. In Spring 2003, his victims banded together and
Casstrated him (plonked him and anyone who replied to his trolls).
Then his newsgroup service provider yanked his cross-posting
privileges because Roscoe had so badly abused them. Roscoe is now
forbidden to cross-post and is in virtually everyone's kill files. So
he has jettisoned his "Cass" brand name, and tries to disrupt a few
selected newsgroups under noms de spam which change daily, sometimes
hourly, just to slip past his Casstrators' filters.

Want more detail? As shown at the link above, Roscoe used the Cass
persona to maliciously cross-post a HUGE volume of trolls among a
rotating list of newsgroups including:
rec.autos.tech
three RV newsgroups
some woodworking newsgroups
a few welding/metalworking newsgroups
various city-oriented newsgroups, mostly in Texas (Austin, Houston,
DFW), ranging from restaurants, for-sale, Internet config, and general
some other newsgroups.
You will see in Google Groups that he would change his five-newsgroup
cross-posting selection each time he posted to cause as much confusion
as possible.

At the peak of his nasty career, the Casshole's disruptions accounted
for 50% of the posts on the high-volume newsgroup
rec.outdoors.rv-travel and a yet higher percentage on the smaller
newsgroups which he victimized. He single-handedly drove away regulars
and newbies alike, not-so-slowly strangling that newsgroup community.

Then, predictably, the Cass hit the fan. Tens of thousands of
participants on scores of newsgroups simultaneously became fed up with
this crackpot; we all plonked him and anyone who replied to him. In a
few days Roscoe found himself Casstrated.

And a couple of thousand people asked his Usenet provider (Chris
Caputo, who likes to call himself Altopia) to scrape Roscoe off
Altopia's shoe. Caputo wouldn't do that (losing the $5 or $10 which
Roscoe pays Caputo each month to keep Roscoe's Houston-area ISP a
secret), but Caputo did cut-off Roscoe's cross-posting privileges. If
I recall correctly, that happened on June 18, 2003 -- you will see in
Google Groups that the insane Cassposting suddenly stopped right
around then.

So, Cass is now forbidden to cross-post and virtually everyone has
plonked him. How is he to continue his crusade of damaging newsgroups,
you ask? By:
[1] focusing on a few newsgroups, including this one, since Caputo
won't let him maliciously cross-post anymore
[2] changing his From name and email address with virtually every
post in order to defeat the filters of those who had previously
Casstrated him. (He will bleat that it is an anti-spam measure, but
anyone who knows squat about newsgroups and spam will tell you it is
solely an anti-filtering measure directed against YOU.)

Now, here's the good news, news which might restore your faith in the
intelligence of the common man. ALMOST NO ONE IS REPLYING TO ROSCOE'S
TROLLS. Despite the newsgroup focus, and despite a different shade of
lipstick on the pig each day, no one is biting on Casshole's trolls!
YES!!

Check Google Groups. Casshole's trolls are still getting an occasional
reply, but they are all from a tiny handful of needy people. Casshole,
the grand disrupter and would-be destroyer of newsgroup communities,
is dead meat.

So, you tiny handful of needy people, PLEASE don't keep this joke
alive. Stop replying to the joke -- and you few are the only ones
replying -- thereby leaving Casshole to chatter to himself and to his
sock puppets. Do the right thing.

--RW