No, I only tried starting it in 'park'. I can't recall having to ever put
on the brake to start it but I will try it in case my memory is faulty.
That would really be something if all of this came down to that being the
problem. I would want to kill Helms.
I think we are going astray here. I guess this is normal since you have a
book on the '94 and my book is about the '96.
I don't recall what you are calling the DLC unless it is the main computer
(PTCM - Powertrain Control Module). Nevertheless, the VLCM gets at least
one signal on its pin 12 which is labeled fuel-pump control input. That
comes from pin 80 on the PTCM. However, the what I am calling the low-speed
feed to the pump or regular running signal exclusive of the '2-second' prime
pulse, may be coming from the data buss. This is where we run afoul of
I don't know what EDM fans are unless you mean the air-conditioning
fans/blower/s. The VLCM does not control those/it.
The VLCM only controls the engine cooling fans, i.e., on-off and variable
I can't dynamically test the gate of the pump control mosfet and compare it
to the fan driver mosfets UNLESS I got to one heck of a lot of trouble by
making up a patch-cord to tap into those gates while the VLCM is installed
and under power.
I don't know about you being nice. You seem nice to me. However, my
orignial post was intended to provoke thought.
I knew that by saying 'any REAL experts', would gain attention and only the
most confident of the lot would respond, if at all.
It was a sort of 'throwing down of the gaunlet' alerting the incompetent
that this was a problem that was going to take some real thought and
in-depth analysis. Yep, that probably sounds haughty but, as you know,
there are a few folks out there who will say to change the fuse and buy a
Regardless, I appreciate your competent help.
If you are saying that the VLCM controls the air-conditioning blower/s, I
disagree. I could be wrong but I think it (VLCM) controls the engine
cooling fan, the fuel-pump and the a/c clutch.
It really doesn't matter for my problem but it may help if we agree on this
as that will mean we are on the same page.
What seems to be upsetting you? Are you upset because at one time I
mentioned that there are a lot of crooks in this business and some crooks
got upset and began a flame war to run me off and I wouldn't run?
That is exactly the truth and you know it. I see that you are still a
person who likes to cause and stir up trouble.
Backyard Mechanic seems to be a very nice and knowledgeable person. I
didn't expect to meet someone on here with as much knowledge as he
Bob, again, why are you trying to stir up trouble?
Being polite is what most mature adults are in their normal state. Those
adults have learned that courtesy and friendliness is a lot more fun and
helpful than being nasty and mean.
I don't know where you came in on the original brouhaha but I had only made
a comment about there being a lot of crooks in this industry and it upset
some folks (apparently the crooks) and it all went to Hell from there.
Now, as you know, I don't run from trouble. My personal philosophy is that
if you run, you only embolden the cowards and bullies to continue with the
next fellow that they don't like. So, I always try to hit harder and more
often. If you come in the middle of a fight, it is hard to tell who started
it and who is simply refusing to take it.
Regarding Backyard Mechanic, I am not sure but I think he doesn't need you
telling him who to talk with and who to ignore.
Are you Knutson?
Cass, You may want to share the year with us, this could have EEC4 or 5.
Either way, the relay has power supplied by the battery all the time. The
variable is that ground for the relay is provided by the PCM, which sends
power to the fuel pump. Your EVTM should be enough to troubleshoot this.
Make sure that power comes in where it should, if that's OK, try grounding
the wire to the PCM instead of holding the relay, if this works, trace your
wiring or check your PCM.
I'm sorry, I thought that I had mentioned the year but see that I did not.
The car is a 1996 Lincoln Mark VIII.
As I mentioned in another post, the relay IS getting 12 volts and if I
ground the other side of the coil, the relay pulls in.
The problem is that the relay is not being grounded and that ground comes
from the VLCM and that unit is told what to do about the fuel pump by the
PTCM. So, I am not sure if the problem is IN the VLCM or the PTCM or
Thanks, Jim. I would appreciate it.
I just bought a 17 cd set about Ford. It hasn't arrived.
The guy says that it is the same information that Ford uses. I don't know
if that means the cds are from Ford or it has Ford info contained on the
This has been a real beast to diagnose.
Thanks for the document. It is a little hard to read as it is squashed
down. Also, it seems to be just a sort of block diagram or theory of
operation in block form rather than the actual circuitry. Where your
document shows a pin 13, for control of the relay, my book shows pin 12 of
the VLCM going to pin 80 of the PTCM.
IF IT IS REALLY PIN 13 then, that may be the problem as that hasn't been
checked, that I can recall. Pin 13 isn't even called out in the EVTM other
than showing it in the pictorial view of the EVTM.
Pin 30 is the high side of the relay contacts while pin 87 is going to the
fuel-pump; both of these being on the VLCM. Your document shows different
What a beast!
Thanks for the diagram. I have that one. However, I have traced the wires
associated with the VLCM to the fuel-pump relay and all are good and measure
< 1 ohm. I also am getting 12 volts to the high side of the relay. I have
measured the feedback circuits from the VLCM back to the Power-train control
module and all look good. I have measured the grounded side of the f.p.
relay back to the VLCM and it is good so, it has to be that either the VLCM
is not being told to turn on the relay or the VLCM itself is defective OR
the PTCM is not telling the VLCM to turn on the f.p. due to some other
sensor give the PTCM the information to hold off on the fuel-pump power.
The pins on the VLCM are fine as are the pins inside the connector that
mates with the VLCM.
I just wish I knew how to tell which module it is. It has to either be the
VLCM or the PTCM UNLESS it is a sensor going to the PTCM telling it to not
power the fuel-pump.
This one is a real Sherlock Holmes job and is a challenge to me.
Thanks for the document.
i got a 93 taurus and the integrated control module(constant control
relay) did the same thing to the a/c (voltage to the a/c compressor)..
probably got what i have... i got the $65 shop manual and the $32
electrical/vacuum trouble shooting guide, but i like you dont have the
Power control manual which helm want $300 for... the books i have walk
you to the steps to check everything up until the Power control.. that
is where mine stopped also... i got the a/c working dont know how, it
just started working.. i think it was the contacts in the relay for the
a/c i did not take the module apart to find out yet.. next time it stops
working i will.. i have been on various newsgroups/boards with this and
found that some people check the relay by taking it apart and
resoldering wires in it.. probably not your problem as you get no signal
from the Power control module to the relay.. on mine if this is the case
there is another relay(sensor??) that is not operating correctly and
feeding bad info into the Power control module...look for that in the
electrical/vacuum troubleshooting book....
Thanks for the reply.
The a/c clutch is controlled by the variable load control module in mine, as
well. My module also controls the engine cooling fan. The fuel pump gets
turned on by this module but the module gets info from the power-train
control module and as you say, I suspect some sort of other sensor is
telling all of this to NOT turn on the fuel pump.
I will keep plugging.
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