Honda Car Forum

Anyone ever repair a funky ECM by opening it up and cleaning up any
bad solder joints? Will the ECM avoid sending fuel if it sees
something "wrong" at its sensors although there aren't any codes
stored? Should I toss the ECM at this point?

Long nauseating details and plea follow:

Recap: 94 Accord with the classic main relay (PGM-FI) symptoms (no
fuel pump sound for 2 seconds as required when starting, check engine
light on, can't start) with a twist: It only fails in a cold car when
ambient is around above about 70F/27C, *and* leaving the key in the II
(IGN) position for anywhere from 1 to 4 minutes has always allowed the
second relay and then the fuel pump to kick in, CIL goes off and we're
off. Never a problem while driving, and if the engine is warm it's
never a problem starting. It also isn't a problem when the entire car
has cooled to the low 60s/low 20s F/C or below. Cranking it doesn't
help.

What I've done: I've verified there's no 12v back at the fuel pump
when this happens but for good reasonI've measured battery voltage
at the relay pins 6 (good) and 1 (bad) and back at the ECM A25&B1 and
A7 (these are the connections to the relay) where it's good and bad
(both at Vbatt). I've jumpered the service connector and the CIL
stays on all the time. I've got good grounds at the ECM A connector
and the PGM-FI.

What seems to be busted: WTF is up with my ECM? The skiz show the
fuel pump relay in the PGM-FI won't close unless the ECM pulls down
its A7 (which is PGM-FI pin 1). It doesn't pull it down, not unless
the car is left in II/IGN for a couple of minutes under the conditions
above.


Some specific questions:

- What else am I missing?

- Does the ECM look for other things, a sensor in a sane range or
something other than battery voltage coming off of PGM-FI 6, before
it'll turn on the fuel pump for the 2 seconds?

- Is it worth cracking open the ECM to reheat any obviously flakey
solder joints? Can the ECM be cracked open easily?

- Anyone have a compatible ECM they'd loan me to do a swap check if
I've ruled out everything else?

Howard Goldstein wrote:
> Anyone ever repair a funky ECM by opening it up and cleaning up any
> bad solder joints? Will the ECM avoid sending fuel if it sees
> something "wrong" at its sensors although there aren't any codes
> stored? Should I toss the ECM at this point?
>
> Long nauseating details and plea follow:
>
> Recap: 94 Accord with the classic main relay (PGM-FI) symptoms (no
> fuel pump sound for 2 seconds as required when starting, check engine
> light on, can't start) with a twist: It only fails in a cold car when
> ambient is around above about 70F/27C, *and* leaving the key in the II
> (IGN) position for anywhere from 1 to 4 minutes has always allowed the
> second relay and then the fuel pump to kick in, CIL goes off and we're
> off. Never a problem while driving, and if the engine is warm it's
> never a problem starting. It also isn't a problem when the entire car
> has cooled to the low 60s/low 20s F/C or below. Cranking it doesn't
> help.
>
> What I've done: I've verified there's no 12v back at the fuel pump
> when this happens but for good reasonI've measured battery voltage
> at the relay pins 6 (good) and 1 (bad) and back at the ECM A25&B1 and
> A7 (these are the connections to the relay) where it's good and bad
> (both at Vbatt). I've jumpered the service connector and the CIL
> stays on all the time. I've got good grounds at the ECM A connector
> and the PGM-FI.
>
> What seems to be busted: WTF is up with my ECM? The skiz show the
> fuel pump relay in the PGM-FI won't close unless the ECM pulls down
> its A7 (which is PGM-FI pin 1). It doesn't pull it down, not unless
> the car is left in II/IGN for a couple of minutes under the conditions
> above.
>
>
> Some specific questions:
>
> - What else am I missing?
>
> - Does the ECM look for other things, a sensor in a sane range or
> something other than battery voltage coming off of PGM-FI 6, before
> it'll turn on the fuel pump for the 2 seconds?
>
> - Is it worth cracking open the ECM to reheat any obviously flakey
> solder joints? Can the ECM be cracked open easily?
>
> - Anyone have a compatible ECM they'd loan me to do a swap check if
> I've ruled out everything else?



first things first - have you repaired/replaced the main relay?

On Sat, 09 Feb 2008 06:37:04 -0800, jim beam <spamvortex@bad.example.net> wrote:
: first things first - have you repaired/replaced the main relay?

Damn it I rewrote this article and snipped out the bits where I
originally wrote that I resoldered everything on the old main relay's
PCB, saw no change, got a new one, no difference.

(FWIW I *think* the tests rule out the main relay since its second
relay won't ever close if both ECM leads off of it are at +12....)(?)

I've also been all over the grounds like stink on you know
what... Good ground to the body from the main relay and at the two
ground leads on the A connector on the ECM

Howard Goldstein wrote:
> On Sat, 09 Feb 2008 06:37:04 -0800, jim beam <spamvortex@bad.example.net> wrote:
> : first things first - have you repaired/replaced the main relay?
>
> Damn it I rewrote this article and snipped out the bits where I
> originally wrote that I resoldered everything on the old main relay's
> PCB, saw no change, got a new one, no difference.

ok.


>
> (FWIW I *think* the tests rule out the main relay since its second
> relay won't ever close if both ECM leads off of it are at +12....)(?)
>
> I've also been all over the grounds like stink on you know
> what... Good ground to the body from the main relay and at the two
> ground leads on the A connector on the ECM

it's possible it's the ecm, but unlikely unless you've shorted some
leads. best way of finding out is to get another one from a junkyard
and test. in my area, they're about $35. what code do you get from the
old one when the check engine light is on?

other than that, check the ignition switch itself - they tend to fail at
high mileage, particularly when the key is part of a heavy key chain
with lots of junk on it.

On Sat, 09 Feb 2008 07:01:53 -0800, jim beam <spamvortex@bad.example.net> wrote:
: Howard Goldstein wrote:
: > On Sat, 09 Feb 2008 06:37:04 -0800, jim beam <spamvortex@bad.example.net> wrote:
: > : first things first - have you repaired/replaced the main relay?
: >
: > Damn it I rewrote this article and snipped out the bits where I
: > originally wrote that I resoldered everything on the old main relay's
: > PCB, saw no change, got a new one, no difference.
:
: ok.
:
:
: >
: > (FWIW I *think* the tests rule out the main relay since its second
: > relay won't ever close if both ECM leads off of it are at +12....)(?)
: >
: > I've also been all over the grounds like stink on you know
: > what... Good ground to the body from the main relay and at the two
: > ground leads on the A connector on the ECM
:
: it's possible it's the ecm, but unlikely unless you've shorted some
: leads. best way of finding out is to get another one from a junkyard
: and test. in my area, they're about $35. what code do you get from the
: old one when the check engine light is on?

This is what's so frustrating. There shouldn't have been anything
shorted, didn't even jump another car. I see it's about $39 on ebay
and another $12 shipping which is probably what it'd cost to drive up
to the nearest junkyard that had it for $35 so that's an option,
especially if someone else has seen what I see.

With the test jumper installed the CIL stays on continuously even
after the second relay comes on. I think that means it doesn't have
any codes.

:
: other than that, check the ignition switch itself - they tend to fail at
: high mileage, particularly when the key is part of a heavy key chain
: with lots of junk on it.

What would be a symptom of this, would I get the first relay 'clunk'
but not the second 'clunk' that energizes the fuel pump for 2 sec?

Howard Goldstein wrote:
> On Sat, 09 Feb 2008 07:01:53 -0800, jim beam <spamvortex@bad.example.net> wrote:
> : Howard Goldstein wrote:
> : > On Sat, 09 Feb 2008 06:37:04 -0800, jim beam <spamvortex@bad.example.net> wrote:
> : > : first things first - have you repaired/replaced the main relay?
> : >
> : > Damn it I rewrote this article and snipped out the bits where I
> : > originally wrote that I resoldered everything on the old main relay's
> : > PCB, saw no change, got a new one, no difference.
> :
> : ok.
> :
> :
> : >
> : > (FWIW I *think* the tests rule out the main relay since its second
> : > relay won't ever close if both ECM leads off of it are at +12....)(?)
> : >
> : > I've also been all over the grounds like stink on you know
> : > what... Good ground to the body from the main relay and at the two
> : > ground leads on the A connector on the ECM
> :
> : it's possible it's the ecm, but unlikely unless you've shorted some
> : leads. best way of finding out is to get another one from a junkyard
> : and test. in my area, they're about $35. what code do you get from the
> : old one when the check engine light is on?
>
> This is what's so frustrating. There shouldn't have been anything
> shorted, didn't even jump another car. I see it's about $39 on ebay
> and another $12 shipping which is probably what it'd cost to drive up
> to the nearest junkyard that had it for $35 so that's an option,
> especially if someone else has seen what I see.
>
> With the test jumper installed the CIL stays on continuously even
> after the second relay comes on. I think that means it doesn't have
> any codes.
>
> :
> : other than that, check the ignition switch itself - they tend to fail at
> : high mileage, particularly when the key is part of a heavy key chain
> : with lots of junk on it.
>
> What would be a symptom of this, would I get the first relay 'clunk'
> but not the second 'clunk' that energizes the fuel pump for 2 sec?

the first clunk is when contact is made, and the fuel pump comes on.
the second is when the pump is turned off again - it's a safety feature
that prevents the pump puring gas into a flaming engine compartment in
the event of a crash. if your pump is being switched on, but not off
again, yes, there's something wrong.

can't recall the code reading procedure on your vehicle, but if the
light is on, there will be one. where you read it from is another matter.

Howard Goldstein wrote:
> Anyone ever repair a funky ECM by opening it up and cleaning up any
> bad solder joints? Will the ECM avoid sending fuel if it sees
> something "wrong" at its sensors although there aren't any codes
> stored? Should I toss the ECM at this point?
>
> Long nauseating details and plea follow:
>

--------------------

If you sit there with key in position II and nothing happens (no fuel
pump), smack the dash on the left side. If the fuel pump goes
GzzzzzzCLICK, the car will now start. They NEVER fail while the engine
is running because the vibration makes the bad solder connection work
enough.
Resolder or replace the relay.

'Curly'

On Sat, 09 Feb 2008 11:29:54 -0700, motsco_ <motsco_@interbaun.com> wrote:
: Howard Goldstein wrote:
: > Anyone ever repair a funky ECM by opening it up and cleaning up any
: > bad solder joints? Will the ECM avoid sending fuel if it sees
: > something "wrong" at its sensors although there aren't any codes
: > stored? Should I toss the ECM at this point?
: >
: > Long nauseating details and plea follow:
: >
:
: --------------------
:
: If you sit there with key in position II and nothing happens (no fuel
: pump), smack the dash on the left side. If the fuel pump goes
: GzzzzzzCLICK, the car will now start. They NEVER fail while the engine
: is running because the vibration makes the bad solder connection work
: enough.
: Resolder or replace the relay.

Hi, we chatted about this a few months ago. Neither resolder nor
replace makes no difference. Sitting there with the key on II for a
few minutes and it starts working. The ECM isn't pulling the second
relay down

On Sat, 09 Feb 2008 10:28:21 -0800, jim beam <spamvortex@bad.example.net> wrote:
: Howard Goldstein wrote:
: > On Sat, 09 Feb 2008 07:01:53 -0800, jim beam <spamvortex@bad.example.net> wrote:
: > : Howard Goldstein wrote:
: > : > On Sat, 09 Feb 2008 06:37:04 -0800, jim beam <spamvortex@bad.example.net> wrote:
: > : > : first things first - have you repaired/replaced the main relay?
: > : >
: > : > Damn it I rewrote this article and snipped out the bits where I
: > : > originally wrote that I resoldered everything on the old main relay's
: > : > PCB, saw no change, got a new one, no difference.
: > :
: > : ok.
: > :
: > :
: > : >
: > : > (FWIW I *think* the tests rule out the main relay since its second
: > : > relay won't ever close if both ECM leads off of it are at +12....)(?)
: > : >
: > : > I've also been all over the grounds like stink on you know
: > : > what... Good ground to the body from the main relay and at the two
: > : > ground leads on the A connector on the ECM
: > :
: > : it's possible it's the ecm, but unlikely unless you've shorted some
: > : leads. best way of finding out is to get another one from a junkyard
: > : and test. in my area, they're about $35. what code do you get from the
: > : old one when the check engine light is on?
: >
: > This is what's so frustrating. There shouldn't have been anything
: > shorted, didn't even jump another car. I see it's about $39 on ebay
: > and another $12 shipping which is probably what it'd cost to drive up
: > to the nearest junkyard that had it for $35 so that's an option,
: > especially if someone else has seen what I see.
: >
: > With the test jumper installed the CIL stays on continuously even
: > after the second relay comes on. I think that means it doesn't have
: > any codes.
: >
: > :
: > : other than that, check the ignition switch itself - they tend to fail at
: > : high mileage, particularly when the key is part of a heavy key chain
: > : with lots of junk on it.
: >
: > What would be a symptom of this, would I get the first relay 'clunk'
: > but not the second 'clunk' that energizes the fuel pump for 2 sec?
:
: the first clunk is when contact is made, and the fuel pump comes on.

That's the problem actually. The first click is supposed to energize
the ECM. It's the second click that should happen almost
simultaneously with the first that runs the pump. If things are
working properly you don't notice the second click. Then there's a
third click after 2 seconds when the pump stops.

I can tell this is the way it's working since the second click is
what's delayed when the car is at ambient, then I get a third click as
normal when the 2 seconds passes.


: the second is when the pump is turned off again - it's a safety feature
: that prevents the pump puring gas into a flaming engine compartment in
: the event of a crash. if your pump is being switched on, but not off
: again, yes, there's something wrong.
:
: can't recall the code reading procedure on your vehicle, but if the
: light is on, there will be one. where you read it from is another matter.

It's really easy with this model. A jumper in the service connector
and then stare at the engine light (or what they call a Malfunction
Indicator Light). According to the service manual if the light stays
on while the jumper is in then there aren't any codes, which is what
mine does.

Looking through the manual some more it looks like ECM voltage is
supplied for some reason from the mail relay and then through a
connector off of the IAC. Now that I did touch when I was adjusting
idle speed about 2 years ago, but this problem arose about 6 months
ago.

hgoldste@mpcs.com (Howard Goldstein) wrote in
news:1202582202.68680@news.queue.to:

> On Sat, 09 Feb 2008 11:29:54 -0700, motsco_ <motsco_@interbaun.com>
> wrote:
> : Howard Goldstein wrote:
> : > Anyone ever repair a funky ECM by opening it up and cleaning up
> : > any bad solder joints? Will the ECM avoid sending fuel if it sees
> : > something "wrong" at its sensors although there aren't any codes
> : > stored? Should I toss the ECM at this point?
> : >
> : > Long nauseating details and plea follow:
> : >
> :
> : --------------------
> :
> : If you sit there with key in position II and nothing happens (no
> : fuel pump), smack the dash on the left side. If the fuel pump goes
> : GzzzzzzCLICK, the car will now start. They NEVER fail while the
> : engine is running because the vibration makes the bad solder
> : connection work enough.
> : Resolder or replace the relay.
>
> Hi, we chatted about this a few months ago. Neither resolder nor
> replace makes no difference. Sitting there with the key on II for a
> few minutes and it starts working. The ECM isn't pulling the second
> relay down
>



Disconnect the Main Relay's plug from the Main Relay. Connect a multimeter
(set to Ohms) between the plug's Terminal 8 and a body ground.

Turn the key to "II". At thre same time as you turn the key, watch the
multimeter carefully. Do you get continuity for two seconds?

Have you checked the ECU ground at the thermostat housing? Have you checked
the engine grounds at the transmission housing and from valve cover to
shock tower?


--
Tegger

The Unofficial Honda/Acura FAQ
www.tegger.com/hondafaq/