[Diy_efi] CS Failure

Tue Nov 29 18:12:28 UTC 2005

  Remembering back to my BMW repair days; these "LKM" boxes used to be bad
about solder cracking. This happened at all the high current junctions on
the circuit board where there was a large-gauge terminal soldered to the
board. Such as where the relays and 32-pin connector terminals went into the
board.
  There is a trick to repairing this type of solder cracking as it tends to
recur.  Use a solder remover to expose the pin. Wrap copper "bus wire"
aroung the pin leaving both ends exposed out over the board. Re-solder this
whole connection using Silver Bearing Solder and a high wattage (30)
soldering iron.
  This should fix the solder cracking.
  I worked mainly on mid-80s cars so your car might not have the same setup.
This is just my two cents worth!
David

----- Original Message ----- 
From: Daniel R. Nicoson
To: diy_efi at diy-efi.org
Sent: Tuesday, November 29, 2005 7:33 AM
Subject: RE: [Diy_efi] CS Failure

Tom,

That's the best help I've had on this issue.  The E-39 discussion group I
listen in on doesn't have any solutions when I ask on this one.

I'll take a look at those two solutions.

Thanks!

Dan Nicoson

-----Original Message-----
From: diy_efi-bounces at diy-efi.org [mailto:diy_efi-bounces at diy-efi.org]On
Behalf Of Tom Visel
Sent: Monday, November 28, 2005 11:07 PM
To: diy_efi at diy-efi.org
Subject: Re: [Diy_efi] CS Failure

Most likely you have a bad Lamp Control Module.  It's located in the forward
power distribution box under the hood, and it's about the size of a box of
cigarettes, with a 32-pin connector.  It controls current flow to all of the
exterior lights that aren't headlamps, so if you're smoking bulbs, it's
probably the culprit.  If you have non-stock HID headlamps or high-wattage
bulbs in your headlamps, it tends to kill this idiot box, which gets its
power from the headlamp system.

Bad news:  The modules cost mega bucks, and there are many different part
numbers to make JY hunting harder.  Good news:  You can install LED
replacements for your taillamps, for less money than the module.  The LED
lamps will have a current limiting resistor in them so they won't accept
extra current and die if the module is getting stupid.  You have an
electronic flasher (hope it never dies, it's spendy too!) so your bulb flash
rate shouldn't vary; however, if it does, you can get a 6 ohm, 50W resistor
and place it in parallel with the LED turn signal bulb and restore your
previous flash rate.  I buy LED lamps from
http://www.superbrightleds.com/1157.htm   Good service, good product, good
selection, haven't had one die yet.
.
Hope this helps!
TomV

Daniel R. Nicoson wrote:
Tom,

I have a 1998 BMW 540 that eats one or two rear taillights each month.  I've
never seen anything like it in over 20 years of car ownership and 19 cars.
The battery is in the trunk, I assume all power goes forward to the engine
before coming back to the taillight assemblies.

I did put my oscilloscope on the car once to see if there were any weird
spikes, didn't see anything.

I've cleaned all the bulb sockets, cleaned the multipin connectors, even
tried conducting grease at the contact points.  Still loose one or two bulbs
each month.  Any ideas here?

I'd drive it into your shop and pay for a proper diagnosis if you're
anywhere close to western Pennsylvania!

Thanks,

Dan Nicoson

-----Original Message-----
From: diy_efi-bounces at diy-efi.org [mailto:diy_efi-bounces at diy-efi.org]On
Behalf Of Tom Visel
Sent: Monday, November 28, 2005 12:38 PM
To: diy_efi at diy-efi.org
Subject: Re: [Diy_efi] CS Failure

I own a repair shop specializing in electrical and driveability diagnosis
and repair.  If my shop had no overhead, I could probably retire on the
income I make from alternators which other shops (or customers) installed
and had die on them due to high resistance in the output circuit.
Intermittent or poor lamp circuit (L terminal) connections will cause
intermittent no-charge problems.  Poor or no connection at the sense (S
terminal, the big one in the regulator connector) may cause the alternator
to undercharge, but rarely to overcharge or burn out.  What burns out
CS-series (and indeed, all) alternators is heat.  Internal heat, cause by
overwork because the alt can't charge the battery properly and/or can't
monitor the battery's state of charge.  To diagnose your vehicle:

With a fresh known good alternator and a fully charged battery (12.66 V or
better) installed, check the voltage drop on the positive and negative sides
of the charging circuit.  To do this, get the alternator under a good load:
engine running, lights on, heater blower and A/C running, cooling fans going
if you have them.  If you have an ammeter, clamp type or no, measure the
current flow through the system.  Positive or negative side will be the
same, and be sure to include all of the wires at the battery in your
measurement if using a clamp-type probe.  Note the reading.

While the engine is still running, using your DVOM, measure the voltage
between the alternator case (the case thru-screws are good candidates) and
the battery negative terminals.  Note the reading.  Now measure the voltage
between the battery positive terminal and the alternator output stud.  Note
the reading.  If you got negative readings, ignore the sign.  It's the
number that counts.

Total your two voltage readings.  This is the "voltage drop" in the charging
circuit.  It is a reflection of the resistance in the circuit - resistance
which will put a long-term strain on your alternator's diodes and overheat
and kill them.  If you get a total of greater than 0.1 Volt per 10 Amps of
alternator output, that is too much voltage drop and the connections and/or
wires and cables will need to be improved.  For a standard 105 amp CS130, 10
gauge wire straight to the battery, with a 14 gauge fusible link, is
sufficient.  For a "high output" alternator, 8 gauge with a 12 gauge fusible
link is recommended.  Also, you can't have too many grounds.  Besides
keeping your alternator alive, quality grounds (less than .050 volts drop)
will help stave off computer stupidity.  You would be astonished at the
number of vehicles that leave my shop with a sub-$150 repair (diagnosis,
labor, parts, tax) when other shops told the customer that s/he needed a new
ECM or a stack of new sensors.

TomV

Clayton Martiniuk wrote:
Hello, I have an 1994 Chevy 350 that Keeps eating alternators for some
reason. They seem to work for about two days and then shit out. I have a cs
series alternator powered with one exciter/indicator wire at the F terminal.
Looking at the indicator bulb, I'll start the truck, the light will go off
for a while but turn back on intermittently. I heard that these years of
trucks seem to have a problem. Some say to ground the back of the case to
the batt but I dont see how on mine. I am probably close to duty cycle but
no major power drains. It gets very cold here around -20 to -50. I am
running an electric fuel pump. I am running an red top optima with 800 cca.
Does this Battery require special needs? Is the answer an larger amperage
generator or am I doing something wrong?
I am sick of buying alternators and no one can seem to figure out whats
happening.
                                                Thank you for your time
                                Clayton Martiniuk

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