'89 Crown Vic computer problem?

Hi all,

I wonder if anyone has any ideas for me on this problem. Car is an '89
Crown Vic, 302, EEC-IV.

For the last couple months or so, occasionally but more & more frequently,
it needs to be cranked several seconds before it starts. Sometimes the
dash lights come on normally as soon as the key is turned; sometimes
they're dead when it starts cranking, then after a few seconds things
light up and it immediately it starts.

The last time it was started, it would start then die immediately; that
happened a half dozen times before it stayed running. At least once
during this process the dash lights went nuts, flashing randomly back &
forth for a second or two. Once it started, it ran fine, but the wipers &
radio didn't work. A little later the wipers & radio worked fine. All
fuses are good, and there have been no electrical problems before this.

My thinking is maybe the computer is dying. Anyone else have a suggestion
of what I should check?

Thanks,
Dan

"Dan Youngquist" wrote

> I wonder if anyone has any ideas for me on this problem. Car is an '89
> Crown Vic, 302, EEC-IV.
>
> For the last couple months or so, occasionally but more & more frequently,
> it needs to be cranked several seconds before it starts. Sometimes the
> dash lights come on normally as soon as the key is turned; sometimes
> they're dead when it starts cranking, then after a few seconds things
> light up and it immediately it starts.
>
> The last time it was started, it would start then die immediately; that
> happened a half dozen times before it stayed running. At least once
> during this process the dash lights went nuts, flashing randomly back &
> forth for a second or two. Once it started, it ran fine, but the wipers &
> radio didn't work. A little later the wipers & radio worked fine. All
> fuses are good, and there have been no electrical problems before this.
>
> My thinking is maybe the computer is dying. Anyone else have a suggestion
> of what I should check?

Lots of problems around that time with ignition switches failing and burning the
cars to the ground. They're cheap. Replace it.

On Thu, 31 May 2007, MasterBlaster wrote:

> Lots of problems around that time with ignition switches failing and
> burning the cars to the ground. They're cheap. Replace it.

Thanks for the reply. Have you actually seen a bad ignition switch cause
the symptoms I described? I can see it doing some of them, but not
others. Most notable in the latter category would be the apparently
random flashing of the dash lights; it seems like a bad switch would make
them all go on & off together. Also the fact that, on the occasions when
it doesn't start right away, sometimes the dash lights come on normally,
and sometimes they don't.

I'm about to go pull the codes from the computer, so I may have a bit more
info shortly.

Thanks,
Dan

On Thu, 31 May 2007, MasterBlaster wrote:

> Lots of problems around that time with ignition switches failing and
> burning the cars to the ground. They're cheap. Replace it.

At first I didn't think that could cause all the symptoms, but I went out
and carefully jimmied the key around a bit, and it looks like it's
definitely flaky. Thanks, it's a lot cheaper & easier than an ECU. That
theory had a couple holes in it anyway.

If you see my first response, please ignore it. I cancelled the post, but
I understand some news servers don't honor the cancel command.

-Dan

>Hi all,
>
>I wonder if anyone has any ideas for me on this problem. Car is an '89
>Crown Vic, 302, EEC-IV.
>
>For the last couple months or so, occasionally but more & more frequently,
>it needs to be cranked several seconds before it starts. Sometimes the
>dash lights come on normally as soon as the key is turned; sometimes
>they're dead when it starts cranking, then after a few seconds things
>light up and it immediately it starts.
>
>The last time it was started, it would start then die immediately; that
>happened a half dozen times before it stayed running. At least once
>during this process the dash lights went nuts, flashing randomly back &
>forth for a second or two. Once it started, it ran fine, but the wipers &
>radio didn't work. A little later the wipers & radio worked fine. All
>fuses are good, and there have been no electrical problems before this.
>
>My thinking is maybe the computer is dying. Anyone else have a suggestion
>of what I should check?
>
>Thanks,
>Dan
First off, without having you read anything else, it doesn't sound
like you have a "computer problem".


While you might think it's right there at the key cylinder, the
"ignition" switch is a plastic/metal sliding contraption a couple of
feet down and fastened to an inside cover on the steering column.
Easy to see where the wires go, hard to get to the switch for actual
testing and replacement. Ignition switch is a misnomer, quite a few
'circuits' go through the thing, The EEC-IV gets its power through a
relay controlled by the ignition switch. It could be bad switch
contacts, or even simpler, a bad/loose connection.

The EEC-IV is a relatively simple processor, chances are if it can
execute a simple set of instructions, it can execute all of them.

Your EEC has no control over whether or not your wipers come on or
not, same with the radio. The EEC doesn't control any 'accessories'
other than perhaps the A/C compressor.

You need to know how the 'circuit' is supposed to work normally, in
order to make educated guesses about when something doesn't work.

From your symptoms, I would look closely at an ignition switch issue,
sliding contacts can wear out too.

I do know that Ford had recalled a lot of models for an upgrade to
move the igniton power and some accessories from going through the
ignition switch and moving the functions over to relays (it was a fire
hazard). Check with any Ford dealer with your vehicle's VIN, and
they'll tell you if the recall applies, and if it's been done. If it
does apply to your model, and if it hasn't been done, they'll do it
for free.
As for the EEC diagnosis from the driver's seat, it's pretty easy:
The following is the 'normal' situation.
When you turn the ignition key from OFF to RUN or START
1. +12 volts gets applied to the coil inside the EEC power relay. The
other side of the coil is attached to the body of the car, so current
flows through the coil, and this 'pulls' a switch contact onto another
contact.
2. This contact applies +12 volts to the EEC itself. (If you have a
diagram handy, this is +VPWR).
3. The EEC, now powered on, goes through a 'bootstrap' (aka Power on
reset) routine of instructions, one of which is to turn on the "Check
Engine" lamp. At about the same time, it also turns on a transistor
that allows current to flow through the Fuel Pump Relay's coil. The
other side of the Fuel Pump Relay's coil is also connected to that
contact that powers up the EEC from the EEC Power Relay. As long as
the "FP" contact is conducting (a couple of seconds in the bootstrap
routine) you should hear the fuel pump running. The EEC's bootstrap
routine includes some static testing of sensors (it pretty much just
amounts to telling itself that the sensors are there, not that they
work as they should), and at the end of it the EEC will turn off the
"Check Engine" light and the fuel pump (waiting for an indication that
the engine is turning), on a 5.0L, that'll be PIP (profile ignition
pickup) coming from the Thick Film Ignition module.
So, if you see the "Check Engine" lamp come on and go off, and hear
the fuel pump run for a couple of seconds, the EEC has powered on, and
gone through the bootstrap routine, and you can be pretty confident
that the EEC, as a 'computer processor' is running correctly.

Once again, if you don't see that the EEC is even powering up, and you
know that intially, power comes through the ignition switch, you
should probably start there in the troubleshooting process, rather
than condemn the EEC outright. If you're not getting the EEC powered
on at the same time the radio and wipers are dead, that's almost a
dead giveaway that something's amiss in the ignition switch and it's
circuits. Watch out though, usually Ford removes power to accessories
when you're in the "START" position.

I would check to make sure the EEC relay is 'good'. They do succumb to
contact wear and the environment (IOW they do go bad), as well as the
Fuel Pump relay.