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In the WIS for my SL400, there is only one wire. And it is a clutchless alternator. I need to double-check my C350 which has a clutched alternator. It it has two wires, I would say it has something to do with activating the clutch.
Wow, you mean a clutch like AC compressor clutch, or those special pulley Overunning pulley OAP or OAD pulley ?
In the WIS for my SL400, there is only one wire. And it is a clutchless alternator. I need to double-check my C350 which has a clutched alternator. It it has two wires, I would say it has something to do with activating the clutch.
Yeah, maybe... but in this video (linked at the time) Tasos is showing an alternator replacement, and this one has a clutched alternator (based on his commentary) and it only has one wire.
Man it would be nice to get a pinout on that regulator. I have switches on both lines but given what a pain it is to remove that thing, I'd hate to start playing around, kill the alternator, and have to get back in there
But... the real question is: which of the two lines on this alternator is the ALT-LIN (see image in my post a few before this one) ?? Do you have access to a schematic that will tell you?
But... the real question is: which of the two lines on this alternator is the ALT-LIN (see image in my post a few before this one) ?? Do you have access to a schematic that will tell you?
Okay here is plan B for a fix TODAY!
You have you 2x switches wired for action but ignore which ALT line is what...
Nothing is going to "self-destruct"...
Lets test this with a two steps procedure "either No1 / Or No2" as follows:
Toggle one of the switches and check ECU faults.
If fault is the ALT-LIN P06xxx you're done!
else toggle both switches around
then check active fault.
> Last steps:
Clear faults besides ALT-LIN stats active.
Check you do have 14.1Volts engine running.
Do "reboot & float"...
Welcome to the land of limited chaos
Post the harness colors once you know which is what.
Last edited by CaliBenzDriver; Jun 26, 2025 at 09:18 PM.
Measure using oscilloscope , you can see LIN signal on a scope.
While at it , the other alien wire maybe we can learn of its signal too.
I am also curious as to why 2 wires.
On AC compressor, it is 3 wires prepared by MB. 2 for AC solenoid and 1 more is for clutch of AC compressor if your car is using it.
3 wire and 3 wire connector from MB wire harness into Denso connector also 3 wires type, but only 2 wires used ( mine) at Denso compressor side.
Well, here's with Orange Off, White On -- seems like a winner. I did not test orange off and white off (full plug disconnect) yet...
By comparison, here's with both Orange and White On -- Interesting it seems to favor dropping the voltage on acceleration.
CONGRATS, you've nailed it!
Now you have all the benefits of stable voltage.
-- Now you have ALT-LIN (ORG) : opened.
-- You left the other ALT connection (WHT) normally connected (switched:ON) since you don't know what it is.
Expectations are IC Display should show 14.1V flat stable "rain or shine" with minimal battery current from 15Amps to near 0A under 15Mn.
Learn to set your Display to "maintenance mode" so you can read your battery sensor vitals.
This validates the "single GND-strap" is glitching or not.
ALT regulates a perfect 14.1V internally - It has no idea what the battery sensor is getting across chassis harness.
Verify live display data to trust what you see!! 👍
Sayonara stock chaos... cancelled with 14.1VDC
> IN A NUTSHELL...
ALT-LIN is (ORG) disconnected with (WHT) as-is.
Last edited by CaliBenzDriver; Jun 29, 2025 at 12:01 AM.
9182338]How did you managed to disconnect only one wire, it is part of the entire plug, did you slice the wire, sorry I am still catching up on this thread.
no worries - it’s a loooooooong thread
I didn’t have room to get to the plug and could only just glimpse it. The M157 is really crammed into the engine bay. I crafted a tool to pull out the locking tab - that worked - then used long needle nose pliers to grab the plug. I couldn’t see well enough with the pliers in place and accidentally ripped the orange wire in half. It's a very thin gauge wire...
Then, because now I absolutely needed to address the wire, I learned that this whole time I could have just unbolted the steering rack without any trouble or needing realignment in about 15 minutes.
With that out of the way, I had enough room to get to the plug and install switch wires. They now run up to the battery compartment.
Last edited by QuadTurboPrius; Jun 29, 2025 at 09:19 AM.
I didn’t have room to get to the plug and could only just glimpse it. The M157 is really crammed into the engine bay. I crafted a tool to pull out the locking tab - that worked - then used long needle nose pliers to grab the plug. I couldn’t see well enough with the pliers in place and accidentally ripped the orange wire in half. It's a very thin gauge wire...
Then, because now I absolutely needed to address the wire, I learned that this whole time I could have just unbolted the steering rack without any trouble or needing realignment in about 15 minutes.
With that out of the way, I had enough room to get to the plug and install switch wires. They now run up to the battery compartment.
Please do share your experience after the unplug : )
So far it seems very stable - but this car has always been very solid.
I've only put maybe 50 miles on it since the unplug, so I'll report back when I get closer to 1k miles.
The oil solenoid unplug and move to 5w-50 has made massive positive improvements to the car. Hopefully this ALT-LIN mod brings an extra dimension of perfection
@CaliBenzDriver -- are you requesting a step-by-step from me?
Last edited by QuadTurboPrius; Jul 1, 2025 at 09:59 AM.
So far it seems very stable - but this car has always been very solid.
I've only put maybe 50 miles on it since the unplug, so I'll report back when I get closer to 1k miles.
The oil solenoid unplug and move to 5w-50 has made massive positive improvements to the car. Hopefully this ALT-LIN mod brings an extra dimension of perfection
@CaliBenzDriver -- are you requesting a step-by-step from me?
everything in this experiment is optional. The combination of a few steps are recommended for results.
ALT-LIN stability is provides more a "network protection" than a voltage boost.
> KEY STEPS... Rebooting chassis + floating battery are as essential as stable 14.1V.
The stock networking of Modules is not particularly stellar - It benefits these 3-steps for *normal* processing speed.
The ECU firmware is built such that CAN bandwidth affects the core engine timings, unfortunately!
Either CGW or ESP/ISM/TCU are impacting ECU/Engine timingd.
The bottom line.... you should notice an improvement step right away from ALT-LIN + REBOOT + Float.
In addition both ECU + TCU will keep adapting their maps over next 1500Mi according to how good/bad work was before.
Little by little good cylinders timings will enable firm throttle then "pressure sensitive" throttle.
Predictable engine throttle will allow TCU to learn best shift-points. Improved CAN-C bandwidth will allow zero delay ECU-TCU realtime cooperation.
Step-by-step the laggy powertrain is gonna become weightless as precise timings improve with cool engine power on tap.
Once ECU+TCU have built solid base maps, RPM response is amazing.
Last edited by CaliBenzDriver; Jul 1, 2025 at 01:56 PM.
So far it seems very stable - but this car has always been very solid.
I've only put maybe 50 miles on it since the unplug, so I'll report back when I get closer to 1k miles.
The oil solenoid unplug and move to 5w-50 has made massive positive improvements to the car. Hopefully this ALT-LIN mod brings an extra dimension of perfection
@CaliBenzDriver -- are you requesting a step-by-step from me?
It is meant to help make things smoother, like the transmission, think of it as before ECU has to multitask (control the alternator and TCU), now just the latter (obviously the ECU does more than that but I want to say, wouldn't it be less stressful if it has less things to do?). That is the idea.
It is meant to help make things smoother, like the transmission, think of it as before ECU has to multitask (control the alternator and TCU), now just the latter (obviously the ECU does more than that but I want to say, wouldn't it be less stressful if it has less things to do?). That is the idea.
The hardware that Bosch, Continental and Siemens deployed is state of the art. The best multicore SOC with a generous chip count are used.
It's sad that these systems are not allowed to run normally.
A few details are used to seed chaos: pressure + voltage + heat + bandwidth + ...
Lately I've been combing the settings of F-SAM. I realized something I call interesting....
--- the solderless CAN-B AirCon module interfere with TCU gear-shift to heat or cool more. I'm disabled that!
--- In addition it can regulate humidity by reading the Windshield humidity sensor... this creates lot's of busy traffic just to run airCon. I disabled that too!
-- Also I've found an ECU setting related to missing "steering pump"
--- Headlights set from factory to keep reading a missing suspension module...
Networking on different Voltage thresholds guarantees retransmit storms - What is this ? this is done by solderless pins to connect module harness randomly marginal. I've physically tested that networking runs reliably faster once soldered, specifically CAN-B and CAN-C: ESP + ISM.
Regaining a stable electrical power is a positive base to minimize some of the built-in mess.
Last edited by CaliBenzDriver; Jul 2, 2025 at 05:09 AM.
The hardware that Bosch, Continental and Siemens deployed is state of the art. The best multicore SOC with a generous chip count are used.
It's sad that these systems are not allowed to run normally.
A few details are used to seed chaos: pressure + voltage + heat + bandwidth + ...
Lately I've been combing the settings of F-SAM. I realized something I call interesting....
--- the solderless CAN-B AirCon module interfere with TCU gear-shift to heat or cool more. I'm disabled that!
--- In addition it can regulate humidity by reading the Windshield humidity sensor... this creates lot's of busy traffic just to run airCon. I disabled that too!
-- Also I've found an ECU setting related to missing "steering pump"
--- Headlights set from factory to keep reading a missing suspension module...
Networking on different Voltage thresholds guarantees retransmit storms - What is this ? this is done by solderless pins to connect module harness randomly marginal. I've physically tested that networking runs reliably faster once soldered, specifically CAN-B and CAN-C: ESP + ISM.
Regaining a stable electrical power is a positive base to minimize some of the built-in mess.
Sad indeed, glad we have folks like you restoring the function of the vehicle : )
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
Slideshow: A one-of-one U.S.-spec Mercedes-Benz SLR McLaren Roadster became even rarer after a factory-backed transformation at McLaren's headquarters.
, it is special pulley but not a clutch.
