Engine Management Units

C

Cursitor Doom

Guest
Hi guys,

I have an EMU from a Land Rover which just suddenly failed one day
without warning as I was driving down the road. I was wondering if
there's any possibility of fixing it, given that schematics are AFAIK
unavailable due to commercial confidentiality. Of course there are some
basic checks that can be done without a diagram, but take a look at this
thing and tell me what I could try doing with it. I've carefully
inspected it close up but can find *nothing* at all visibly wrong with it:

http://tinyurl.com/hvk5eac

BTW, the whole board has been thickly sprayed with clear varnish which
accounts for all the bright dots which appear on some of the parts -
they're not indicative of any failure.

Any suggestions?
 
On 15/03/16 10:02, Cursitor Doom wrote:
Hi guys,

I have an EMU from a Land Rover which just suddenly failed one day
without warning as I was driving down the road. I was wondering if
there's any possibility of fixing it, given that schematics are AFAIK
unavailable due to commercial confidentiality. Of course there are some
basic checks that can be done without a diagram, but take a look at this
thing and tell me what I could try doing with it. I've carefully
inspected it close up but can find *nothing* at all visibly wrong with it:

http://tinyurl.com/hvk5eac

BTW, the whole board has been thickly sprayed with clear varnish which
accounts for all the bright dots which appear on some of the parts -
they're not indicative of any failure.

Any suggestions?
Click to expand...

"My car is broken. Can you tell me how I can fix it?"
 
On Tue, 15 Mar 2016 00:24:02 +0100, Sjouke Burry wrote:

A:try to get a replacement from a car wreckers shop.
B:Or get a magnifier glass and start searching for damage/discoloration.
And check big caps and big transistors.
If no success, try solution A.
Or let repair shop handle it.
Click to expand...

It's up and running again with an exchange unit, but it ran smoother,
quieter and started up quicker with the old unit that failed, so I'd like
to get the old one working again if at all possible.
 
On 15/03/16 10:39, Cursitor Doom wrote:
On Tue, 15 Mar 2016 00:24:02 +0100, Sjouke Burry wrote:

A:try to get a replacement from a car wreckers shop.
B:Or get a magnifier glass and start searching for damage/discoloration.
And check big caps and big transistors.
If no success, try solution A.
Or let repair shop handle it.

It's up and running again with an exchange unit, but it ran smoother,
quieter and started up quicker with the old unit that failed, so I'd like
to get the old one working again if at all possible.
Click to expand...

It can take some time for an ECU to "learn" your engine.
You'll probably find it runs just as well as the old one after
a tank or two of gas.
 
On 15.03.16 0:02, Cursitor Doom wrote:
Hi guys,

I have an EMU from a Land Rover which just suddenly failed one day
without warning as I was driving down the road. I was wondering if
there's any possibility of fixing it, given that schematics are AFAIK
unavailable due to commercial confidentiality. Of course there are some
basic checks that can be done without a diagram, but take a look at this
thing and tell me what I could try doing with it. I've carefully
inspected it close up but can find *nothing* at all visibly wrong with it:

http://tinyurl.com/hvk5eac

BTW, the whole board has been thickly sprayed with clear varnish which
accounts for all the bright dots which appear on some of the parts -
they're not indicative of any failure.

Any suggestions?
Click to expand...
A:try to get a replacement from a car wreckers shop.
B:Or get a magnifier glass and start searching for
damage/discoloration.
And check big caps and big transistors.
If no success, try solution A.
Or let repair shop handle it.
 
In article <56e744db$0$41576$b1db1813$145976f0@news.astraweb.com>,
no.spam@please.net says...
On 15/03/16 10:02, Cursitor Doom wrote:
Hi guys,

I have an EMU from a Land Rover which just suddenly failed one day
without warning as I was driving down the road. I was wondering if
there's any possibility of fixing it, given that schematics are AFAIK
unavailable due to commercial confidentiality. Of course there are some
basic checks that can be done without a diagram, but take a look at this
thing and tell me what I could try doing with it. I've carefully
inspected it close up but can find *nothing* at all visibly wrong with it:

http://tinyurl.com/hvk5eac

BTW, the whole board has been thickly sprayed with clear varnish which
accounts for all the bright dots which appear on some of the parts -
they're not indicative of any failure.

Any suggestions?

"My car is broken. Can you tell me how I can fix it?"
Click to expand...

I have fixed a couple of ECM's and in both cases the Xstal failed
due to mechanical vibration. Power it up using basic shop electrical
prints to the unit and find that the Xstal not operating.

Another one I did was intermitting in some function and popping up
codes randomly. I replaced a couple of caps, fixed..

The coating is tricky to get off without damage.

Jamie
 
In article <nc7i2r$ui0$2@dont-email.me>, curd@notformail.com says...
On Tue, 15 Mar 2016 00:24:02 +0100, Sjouke Burry wrote:

A:try to get a replacement from a car wreckers shop.
B:Or get a magnifier glass and start searching for damage/discoloration.
And check big caps and big transistors.
If no success, try solution A.
Or let repair shop handle it.

It's up and running again with an exchange unit, but it ran smoother,
quieter and started up quicker with the old unit that failed, so I'd like
to get the old one working again if at all possible.
Click to expand...

That will fix itself.

The same is true if you disconnected the battery for a while
with the other one.
 
On Mon, 14 Mar 2016 19:58:50 -0500, M Philbrook wrote:

That will fix itself.

The same is true if you disconnected the battery for a while with the
other one.
Click to expand...

I wish. It's been replaced for over 9 months now and it's still the same
as the day it was fitted.
But this is really about trying to rescue the old one. They don't come
cheap!
 
On Tuesday, March 15, 2016 at 7:08:34 AM UTC-4, Cursitor Doom wrote:

I wish. It's been replaced for over 9 months now and it's still the same
as the day it was fitted.
But this is really about trying to rescue the old one. They don't come
cheap!
Click to expand...

Try this:

Re-install the new unit. Power up the electrical system, but DO NOT start the engine.

Here is the tricky part and be exceedingly careful: While powered up, disconnect the battery, NEGATIVE FIRST. Make sure when that clamp comes off the battery it does so cleanly and quickly. SHORT the positive clamp to the negative clamp immediately and hold for a minimum of 30 seconds. This is the functional equivalent of rebooting the ECU. Shut off the electrical system. Reinstall the battery. Attempt to start. Does this help?

Note: If you have any coded devices such as so-called 'infotainment' systems and such, you will have to re-code them. If you have a chip-based navigation system, remove the chip for this process. But, 3 times in 10, it works. Not bad odds if the alternative is landfill.

If you have a Bosch unit, this is far more likely to work than if you have a British-made unit.... getting back to that old joke: why do the British drink warm beer?

Peter Wieck
Melrose Park, PA
 
On Tue, 15 Mar 2016 06:21:27 -0700, pfjw@aol.com wrote:

On Tuesday, March 15, 2016 at 7:08:34 AM UTC-4, Cursitor Doom wrote:

I wish. It's been replaced for over 9 months now and it's still the
same as the day it was fitted.
But this is really about trying to rescue the old one. They don't come
cheap!

Try this:

Re-install the new unit. Power up the electrical system, but DO NOT
start the engine.

Here is the tricky part and be exceedingly careful: While powered up,
disconnect the battery, NEGATIVE FIRST. Make sure when that clamp comes
off the battery it does so cleanly and quickly. SHORT the positive clamp
to the negative clamp immediately and hold for a minimum of 30 seconds.
This is the functional equivalent of rebooting the ECU. Shut off the
electrical system. Reinstall the battery. Attempt to start. Does this
help?
Click to expand...

We're getting completely off topic in being distracted by the new EMU,
but I'll just answer this point. Every time I leave that vehicle for a
few days, I'll isolate the battery, anyway. So it has been repeatedly
"rebooted" dozens of times since the old one was replaced.

BUT my question is NOT about the new one; it's about how easily the old
ONE can be fixed without schematics (M. Philbrook, many thanks I'll try
your suggestion re xtal).
 
On Tue, 15 Mar 2016 09:58:03 -0500, legg wrote:

On Tue, 15 Mar 2016 11:05:24 -0000 (UTC), Cursitor Doom
curd@notformail.com> wrote:

But this is really about trying to rescue the old one. They don't come
cheap!

The issue is with the new part, not the old one.
Click to expand...

Wrong! The question *solely* concerns the *old* unit that failed.
 
On Tuesday, March 15, 2016 at 10:06:53 AM UTC-4, Cursitor Doom wrote:
On Tue, 15 Mar 2016 06:21:27 -0700, pfjw@aol.com wrote:

On Tuesday, March 15, 2016 at 7:08:34 AM UTC-4, Cursitor Doom wrote:

I wish. It's been replaced for over 9 months now and it's still the
same as the day it was fitted.
But this is really about trying to rescue the old one. They don't come
cheap!

Try this:

Re-install the new unit. Power up the electrical system, but DO NOT
start the engine.

Here is the tricky part and be exceedingly careful: While powered up,
disconnect the battery, NEGATIVE FIRST. Make sure when that clamp comes
off the battery it does so cleanly and quickly. SHORT the positive clamp
to the negative clamp immediately and hold for a minimum of 30 seconds.
This is the functional equivalent of rebooting the ECU. Shut off the
electrical system. Reinstall the battery. Attempt to start. Does this
help?


We're getting completely off topic in being distracted by the new EMU,
but I'll just answer this point. Every time I leave that vehicle for a
few days, I'll isolate the battery, anyway. So it has been repeatedly
"rebooted" dozens of times since the old one was replaced.

BUT my question is NOT about the new one; it's about how easily the old
ONE can be fixed without schematics (M. Philbrook, many thanks I'll try
your suggestion re xtal).
Click to expand...

Whooops! Meant "OLD" unit. Isolating the battery does not constitute a reboot. Shorting the battery leads while the unit capacitors are charged DOES do a reboot. Mere isolation does not. Hence the need to disconnect the battery and short the leads (on the car, not the battery) while the system is energized but the engine not running.

Peter Wieck
Melrose Park, PA
 
On Tue, 15 Mar 2016 11:05:24 -0000 (UTC), Cursitor Doom
<curd@notformail.com> wrote:

On Mon, 14 Mar 2016 19:58:50 -0500, M Philbrook wrote:

That will fix itself.

The same is true if you disconnected the battery for a while with the
other one.

I wish. It's been replaced for over 9 months now and it's still the same
as the day it was fitted.
But this is really about trying to rescue the old one. They don't come
cheap!
Click to expand...

The issue is with the new part, not the old one.

Have you mentioned this to the technicians who made the change?

RL
 
On Tue, 15 Mar 2016 14:25:41 -0500, legg wrote:

On Tue, 15 Mar 2016 14:04:46 -0000 (UTC), Cursitor Doom
curd@notformail.com> wrote:

On Tue, 15 Mar 2016 09:58:03 -0500, legg wrote:

On Tue, 15 Mar 2016 11:05:24 -0000 (UTC), Cursitor Doom
curd@notformail.com> wrote:

But this is really about trying to rescue the old one. They don't come
cheap!

The issue is with the new part, not the old one.

Wrong! The question *solely* concerns the *old* unit that failed.

The issue is your dissatisfaction with the repaired automobile.

You're not in a position to resurrect the old ECU.
Click to expand...

The new ECU in all probability just requires a software tweak. My
question was about the OLD one (at the risk of repeating myself).
 
On 15 Mar 2016, Cursitor Doom wrote
(in article <nc94pu$on1$6@dont-email.me>):

> Wrong! The question *solely* concerns the *old* unit that failed.

Welcome to USENET. There is no “on-topic”!

Under conformal coating it is difficult to examine anything.

Check any large transistors.

I’d also look for broken solder joints on the large devices (caps,
transformer, choke, I/O connectors). Also look closely at the cap “north”
of the big choke. Has it leaked and damaged a trace?

Also check ESR of all the electro caps.

And as was mentioned earlier, be sure the xtal is working.
A success story:

https://www.youtube.com/watch?v=uLIHxqqrY_M

Good luck!
 
If all else looks good, a winding in that transformer might be open. Remove
and “ring” it.
 
On Tue, 15 Mar 2016 14:04:46 -0000 (UTC), Cursitor Doom
<curd@notformail.com> wrote:

On Tue, 15 Mar 2016 09:58:03 -0500, legg wrote:

On Tue, 15 Mar 2016 11:05:24 -0000 (UTC), Cursitor Doom
curd@notformail.com> wrote:

But this is really about trying to rescue the old one. They don't come
cheap!

The issue is with the new part, not the old one.

Wrong! The question *solely* concerns the *old* unit that failed.
Click to expand...

The issue is your dissatisfaction with the repaired automobile.

You're not in a position to resurrect the old ECU.

RL
 
On Tue, 15 Mar 2016 17:21:08 -0700, DaveC wrote:

http://tinyurl.com/hvk5eac

Any chance of posting a super-high resolution image?
Click to expand...

If I can figure out how to get the back off and photograph both sides,
I'll do it. The blurring issue I am having is with the autofocus which is
being hijacked by the two big electrolytics. I'll have to read the
camera's FM and find out how to switch it to manual. These damn things
are so complicated nowadays. :(
 
On Tue, 15 Mar 2016 19:59:53 -0500, legg wrote:

On Tue, 15 Mar 2016 20:01:54 -0000 (UTC), Cursitor Doom
curd@notformail.com> wrote:

On Tue, 15 Mar 2016 14:25:41 -0500, legg wrote:

On Tue, 15 Mar 2016 14:04:46 -0000 (UTC), Cursitor Doom
curd@notformail.com> wrote:

On Tue, 15 Mar 2016 09:58:03 -0500, legg wrote:

On Tue, 15 Mar 2016 11:05:24 -0000 (UTC), Cursitor Doom
curd@notformail.com> wrote:

But this is really about trying to rescue the old one. They don't
come cheap!

The issue is with the new part, not the old one.

Wrong! The question *solely* concerns the *old* unit that failed.

The issue is your dissatisfaction with the repaired automobile.

You're not in a position to resurrect the old ECU.

The new ECU in all probability just requires a software tweak. My
question was about the OLD one (at the risk of repeating myself).

There's not much you can tell from a photograph of limited resolution.
Looking at what you've offered, you might re-examine locally:

http://www.magma.ca/~legg/TVS/EMU_captive_detritus.jpg
http://www.magma.ca/~legg/TVS/EMU_green_reflection.jpg
http://www.magma.ca/~legg/TVS/EMU_red_reflection.jpg
http://www.magma.ca/~legg/TVS/EMU_soluble_contaminant.jpg
http://www.magma.ca/~legg/TVS/EMU_soluble_contaminant_2.jpg

I expect these are mostly reflections in the protective epoxy, or
flow/tension marks formed in its application, but could be signs of
contamination or damage.

Even checking point to point contact is a trial with this stuff.

Vibration produces intermittent faults on assemblies (where the parts
don't actually shear off completely) The most suspect parts are those
with mechanical attributes - the crystal as previously suggested, the
connectors and bulky components. Reflowing the SJ of the latter might be
informative - any uncharacteristic loosness in the soldered material of
the melted joint is a giveaway.

As previous - an intermittent fault is unlikely to result in repeated
DOA symptoms, but it can be recorded for posterity in the firmware, with
DOA symptoms, or break small-signal paths with the same effect.

Did you try a reset on the 'dead' unit, before replacing it?

The fact that its replacement didn't involve the surrender of the defect
unit (for a discount in pricing) is a signal from the mfr regarding
their view on the viability of repair. They are in the most sensible
position to do so, after-warranty.

RL
Click to expand...

Many thanks for that lot above (and the other tips & suggestions others
have come up with). I don't think I will have sufficient time at this
stage to see this through to the end if it turns out to be tricky; I
can't face the prospect of this becoming another saga like the Philips
scope turned out to be. :(
I'll try to get the back off tomorrow...
 
Cursitor Doom wrote:

Hi guys,

I have an EMU from a Land Rover which just suddenly failed one day
without warning as I was driving down the road. I was wondering if
there's any possibility of fixing it, given that schematics are AFAIK
unavailable due to commercial confidentiality. Of course there are some
basic checks that can be done without a diagram, but take a look at this
thing and tell me what I could try doing with it. I've carefully
inspected it close up but can find *nothing* at all visibly wrong with it:

http://tinyurl.com/hvk5eac

BTW, the whole board has been thickly sprayed with clear varnish which
accounts for all the bright dots which appear on some of the parts -
they're not indicative of any failure.

Any suggestions?
Click to expand...
Well, are there any symptoms that can be figured out? Do dash indicators do
something like what they used to do? If it appeas totally dead, there's a
possibility that a voltage regulator or other power switching circuit has
failed. Looks like it has a switching power supply, that will make things a
little harder. Yeah, the conformal coating is really necessary in
automotive gear, but makes rework tough.

Also, check all connectors and other large parts soldered to the board,
breaks in the solder joints are supposed to be a very common cause of
failure.

Jon
 
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