Can anyone read engine wiring diagrams? :) '97 M104
 

I think i can :) but at 17 im just going on assumptions and my basic wiring symbol knowledge and i mean basic :).
Question 1
Look at M16/1, it is the Idle Speed Control(ISC), within the ISC is "r2" which is the Actual Throttle Point Sensor(ATPS) and a white wire is connected to it as an output wire i think. Would that make the white wire the true ATPS wire that informs the ECU of the throttle postion?
From what i can see its an output wire which is good but thats all i know besides "S2" being above it which i thought was the abbreviation for the key ignition switch.
My brain hurts
http://img81.imageshack.us/img81/9211/07612000c1pq7.png
Question 2
Look at B2/5 it is the Mass Air Flow Sensor(MAF) The yellow and green wire is marked as an output wire with "signal" above it. Does that mean that it is the wire that informs the ECU of how air is coming in?
http://img128.imageshack.us/img128/8...12000c2bz9.png
Question 3
Using the diagram of Question 2, please direct your attention to B6/1, it is the cam position sensor. The red and blue wire goes elsewhere to some kind of circuit and the brown and green wire is ground, that leaves the yellow and gray wire. It is the only output wire and has a cool abbrev. "CMP" so......Is the yellow and gray wire the output for cam sensor that informs the ECU of the cams position and engine speed?

Looks like your on the right track to me. I'd suggest you tap into each of the suspect wires and get a voltage reading from each while running. this will verify that you are getting the required signal from each. Fluke sells a nice wire piercing probe that clamps on and probes the insulated wire. This would be the best way to test this. If you can get a graphing multimeter, that would also be best.

As for the cam sensor you are right on. It's some type of hall effect sensor. take a look at the symbols on the diagram. The two on either side are "+" and "-" and the yellow/grey wire is signal.

After another look it seems the only one you will need to probe is the TPS. It appears to be that S2 will run 0 to 5 volts and S1 will run 5 to 0 volts. I'd make sure you get the right one of you need 5V at WOT.

The yellow/green "signal" wire on the MAS is definitely the correct wire. It appears that the yellow/white wire on the left is IAT.

THANK YOU! 300 EVIL, i went to star imports after reading this and my assumptions were verified. I forgot one major thing though, were the hell can i get power from?? :D I completely forgot about that while worrying about the sensors. The SAFCII is half wired on the car and i dont know were to get the power from, im assuming i can ground the two ground wires on the fender where that cluster of brown ground wires are. But in terms of powering the unit i dont know where to start. Here is a picture of the power wires i think.
http://img215.imageshack.us/img215/9...152000ahj1.png
Heres the diagnostic but im still confused:
Pin Pin Information Test Value Comments
F1
E Power input to fuses Note 1
S2
Circuit 15 Power output, supplies several subsystems 12 VDC with key in steering lock position "2" Distribution via X12/5.2
Circuit 15R Power output, supplies several subsystems 12 VDC with key in steering lock position "1" Distribution via X12/5.1
Circuit 15X Power output, supplies F1f8 12 VDC with key in steering lock position "2", not powered during start procedure
Circuit 30 Power input, supplies ignition/starter switch 12 VDC at all times Feed from battery via X4
Note 1 Refer to diagrams in group 00 for consumers of fused circuits

Definitely circuit 15 position 2 on the key switch. This is where all the other engine systems are connected and it won't get interrupted during position 3.

Alright its all done except the illumination wire, it says i need to run this to the illumination for the radio, the illumination module has multiple branches of blue/gray wires going to different things like the radio, climate control, and various lights. This would be the wire i want to tap into correct?

As for the illumination, that also sounds correct. I'd double check everything just in case. You don't want to send +12V to one of your signal wires for instance. I'd say your on the right track though. Your thoughts and evaluation are very clear and concise, you appear very intelligent for 17. Please post some details on your project. We would all like to see what you have going on.

YAHOO! Its done thank you 300 EVIL your a life(and a patience) saver. Here are some pictures, I will disconnect all the wires from the connector and run them through the firewall tommorrow assuming theres a hole big enough somewhere.
Its a little messy and ive got some loose ends to cover but it works
http://i2.tinypic.com/6o0ad1z.jpg
Apexi Unit, cant wait to play with this thing
http://i9.tinypic.com/6uhyr0g.jpg
Heres a bonus, no check engine light even after 5 minutes of various RPM testing
http://i1.tinypic.com/869ba51.jpg

Question #1

I cant picture how s2 is ignition. It looks to me like s1 and s2 are the same perhaps redundant circuits. I very good idea to have redundant circuits in a throttle by wire system. I would check the resistance of both r1 and r2 at full and closed throttle positions. If they are the same they are most likely redundant circuits.

Question #2

I think your right on. The other four wires look like IAT, Inlet Air Temp, power and ground. I believe you IAT is on a seperate connector like mine. You should be able to just check the color of the wires on the IAT sensor.

Question #3

I think your right on.

Some questions for you.

1) What are you trying to do with all this. What is SAFCII.

2) Where did you get these color coded wire diagrams. I'm about to enter wiring hell.

3) Who is Stare Imports.

John Roncallo

Thanks for the response but its all done now but heres a few answers to aid you in your V12 project.

#1
SAFCII = Super Air Flow Converter II
It tricks the MAF to read a higher airflow throughout the rpm range and its highly tunable. Very good thing to have when turbocharging NA cars.
#2
www.startekinfo.com its amazing its $18 to use an entire mercedes benz data base for one day 96 for a week and other stuff. It lets you view basically every part on your car, they have EVERYTHING not just wiring. My subscription just ended but just sign your self up for a day($18) and print off ALL of the wiring diagrams for your V12, thats what i did for my little L6. Its very interesting too and really easy to understand, with all of the diagrams i beginning to figure a way to shut down the pesky ETC on my car. It leaves nothing out in the wiring diagrams and gives you a complete diagnostic(I found that a little late :) )
#3
Star Imports is an AWESOME little shop around where i live in Jeffersonville, Indiana. They completely rewired my 86 300e and i mean completely, body electrics and engine electrics. They are a small pack of mercedes gurus. They are tiny but they rival bigger names like Tafel and have much better customer satisfaction. They always seem to be working on sl500's and Sl600's with V12's like yours, no joke. Theres two Sl600's at their shop right now.

Thanks for the info.

So you turbocharged your NA car, and now your tricking the MAF to output a higher mass flow, which will in turn trick the engine controller to call for more fuel, for an essentially richer mixture across the RPM range. I'm assuming you used an after market engine management system like Megasquirt. I would have assumed you could have tailored your enrichment in the AF map. (Yes/No???)

I was aware of the Startech info subscriptions but I was not aware that it was better than WIS. I have all the wiring diagrams printed in Black and white from WIS but what you have seems a'lot better. I may be delving into that a little more.

It's good to know another independent shop that works on these high end cars. Maybe they have the connectors I've been looking for.

John Roncallo

He's running the stock ECU.

/\Yep :D but i have slight problem, everything works smoothly except one thing, the RPMs. I tied into the only viable wire i thought and its transmitting somewhat. but im getting a 155rpm to 455rpm lol thats not good. The rpm is working tho but maybe i cant actual get RPMs from the cam sensor like you can with the w124 M104's? I dont know, any ideas?

I'm not sure what types of event cycles the SAFC accepts but it's probably along the lines of a Honda Civic. However, their are a few other options that may work. My guess is a lead running form the primary of one of the coil packs although I'm not sure if the coil pack is ground triggered or not. Another option is to buy a pickup that senses a pulse from one of the ignition wires. This is all in theory that the SAFC will except 1 event per cycle to provide RPM. I believe the M104 also has a crank sensor that will provide 3 events every 360 degrees but I'm not positive. I know that's the way it works on the M103. I'll have to check my M104 to be sure. Another option is to get a signal modifier. I helped a guy recently that did a Nissan diesel conversion on his W124 and was trying to get his stock tach to work. I suggested he purchase a signal modifier which he did and it worked for him. If your interested in this route I can ask him what he purchased.

I like the crank solution....simple :D The crank shaft position sensor wire is literally right next to teh camshaft sensor wire in teh ecu(pin 38 is crank pin 39 is cam) so ill de-solder the camshaft splice and hit the crank wire to see what happens. If that doesnt work ill try your other suggested methods. They are the same type of wire in terms of how they output so it should work. You mention honda and i was checking out some H22's with SAFCII's most of their wires matched up to the safcII harness in terms of color but more importantly they ran off the crank sensor like you said. I figured the rpm would be easier lol guess not. Thanks again for helping my helpless ass :D ill redo the rpm in the morning.

crank sensor didnt work ethier it read really high at like 8000 rpm at idle so im stumped.