[Diy_efi] CS Failure

Tue Nov 29 04:07:22 UTC 2005

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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>>  
>>
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