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31 January 2026:
Have to back date this one a little, as pictures were taken, and work began, but this thread was not updated. Acquired a set of W205 C63S seats for the project. Unfortunately, there are two major problems with them. One is that the controls for the seats are on the door panels, and the second is that the computer for the seats is more than a little difficult to integrate into the W209 electronics this car will be running on. The easiest solution would be to use the seat controllers from a W164 ML63 that was parted out several months ago. This would allow for most of the movements of the seats, along with seat mounted controls. The physical mounting of the switches will need the side panels to be cut out of the W205 seats, but that has been done before on the M113K Crossfire, and it can be done again, here.
W205 Seat Controller
This is what the seat controller looks like. The one for the W164 is similar, but an older generation that will play with the W209 electronics of the car a lot better. It would have been possible to translate the protocols, and allow the W205 seat controller to work, but then this would have a domino effect, requiring switches in the doors, which would require cutting up the door panels, mounting them, then trying to make W205 door controllers work, which also would not play well with the rest of the car. Skip all that, and do this: W205 Seat Controller removed and wires traced out
After removing the W205 Seat Controller, the wires for each motor or other function, such as heating, ventilation, airbags, Airscarf and power lumbar control were all identified. Then the W164 controller was added into the seat. This was tested, but have not finished up making it nice and neat, so there will be an update to this step, soon.
31 January 2026:
Have to back date this one a little, as pictures were taken, and work began, but this thread was not updated. Acquired a set of W205 C63S seats for the project. Unfortunately, there are two major problems with them. One is that the controls for the seats are on the door panels, and the second is that the computer for the seats is more than a little difficult to integrate into the W209 electronics this car will be running on. The easiest solution would be to use the seat controllers from a W164 ML63 that was parted out several months ago. This would allow for most of the movements of the seats, along with seat mounted controls. The physical mounting of the switches will need the side panels to be cut out of the W205 seats, but that has been done before on the M113K Crossfire, and it can be done again, here.
W205 Seat Controller
This is what the seat controller looks like. The one for the W164 is similar, but an older generation that will play with the W209 electronics of the car a lot better. It would have been possible to translate the protocols, and allow the W205 seat controller to work, but then this would have a domino effect, requiring switches in the doors, which would require cutting up the door panels, mounting them, then trying to make W205 door controllers work, which also would not play well with the rest of the car. Skip all that, and do this:
W205 Seat Controller removed and wires traced out
After removing the W205 Seat Controller, the wires for each motor or other function, such as heating, ventilation, airbags, Airscarf and power lumbar control were all identified. Then the W164 controller was added into the seat. This was tested, but have not finished up making it nice and neat, so there will be an update to this step, soon.
Very interesting. Now I'm glad that I have a base model! LOL
14 February 2026:
Progress on this project has been slow, due to work and life commitments, but looking forward to stepping up the pace in the coming weeks and months. The seats ought to be finished up in the next day or so. In the meantime, work resumed on engine, including mounting the exhaust manifolds that were made by @NeedsWings . Rob did a fantastic job on these, but the arrival of suitable hardware took a lot longer than expected. I did not want to use regular OEM hardware on these, as experience has shown that with manifolds like these, it will back out. I wanted to use Stage8 Locking Fasteners, which much luck has been had in the past. There was a problem, of course. Mercedes in their infinite wisdom did not use a typical size or thread bolt for the exhaust manifolds on the M156. The M112/113 uses M6. Very typical size. Other engines use M8. Veery typical size. The M156? Some engineer thought M7 - a completely oddball size - ought to be used. Does Stage8 offer M7? No. Does anyone? No. Off to China we go! Nice, gold anodized titanium bolts
After waiting for about 6 weeks, a set of 20 M7x25 titanium bolts arrived. Using Stage8's service, these were shipped to them to be modified to allow their locking system to work on it. This turned out to be very pricey, but not having the headaches of this in the future makes it worth it. Close up of the locking fasteners
These work by slipping the teardrop shaped aluminum locking tab over the head, and then adding the locking E-clip in place to hold them. Now if the bolt tries to work itself out, it can only go so far before the locking tab will hit the manifold, stopping it from going any further. This will keep the fasteners tight, and keep the exhaust manifold gaskets from leaking. If you have ever had a car with a set of headers, then you know what blown manifold gaskets sound like. This will help with that problem tremendously.
14 February 2026 (continued):
Next, the motor mount plates were added. These need to be powder coated, but a test fit of the engine will be made, first, just in case they need to be modified before the final go on this:
One last touch for today was to add SAI block off plates. There is not one for the M156 available, but fortunately M113 style plates can be easily modified and used: The small aluminum plate from Benzformance blocks the SAI ports, as they will not be used in this application
15 April 2026:
Not a huge update, but work is slowly progressing. One of the things happening in this car is the complete conversion of the electrical system to more closely align with the newer architectures found in more modern Mercedes. As the interior is already swapped to W209, the electrical system will be loosely akin to a CLK63 in how it is setup. This means that Sensor Acquisition Modules (SAMs) have to be added, in place of the regular fuse boxes in the Crossfire. A Rear SAM in the trunk area runs rear lighting, rear window defroster and more. The Front SAM takes the place of the regular fuse box, and in addition to having fuses and relays, it controls individual lights, wipers, power to the engine, transmission and more. Think of it like the fuse box, Body Control Module (BCM) and RCM all built into a single module. So begins a rather tedious part of this project - cutting all of the irrelevant wiring out of the car and labeling what is needed to move forward. And that is exactly what has been happening. The Rear SAM is about 75% complete, with all rear lighting and many other functions presently wired up. Attention has now shifted to the Front SAM. The first task was to simply cut each and every wire from the bottom of the original fuse box, and then using heat shrink labels, each circuit was labeled so that when the SAM is wired in, it can be done more easily, without having to trace out every wire again. Many wires are already redundant, and will be abandoned in place. This was chosen over removal as removing them would mean completely de-looming large portions of the wiring in the car, and at this time that was not practical (hah!). How it started
A mess! Order will arise from the chaos How the ECU box currently looks CLK55 main engine bay wiring harness and the front SAM
Work will resume next week, and I expect that it will start to look more reasonable as it goes. That's all for now. Keep checking in!
01 June 2026:
Realize it has been a minute since there was an update. Lot of changes in the garage where the M156 Crossfire is being parked. First off, the "CF55" (M113K Crossfire) sold a little while back, and that allowed us to move our 1991 Ford Mustang LX 5.0 out from against the wall where it has been stored under a car cover for 23 years, and prepare it to be back on the road. Nothing at all wrong with the Mustang, other than it has just sat for over two decades, but as it has been inside, under a car cover, it is in great condition. That space it is in will not go to waste, as we moved in a Bridgeport EZ-Trak Series 1 mill, and a Monarch 10EE lathe in that space. Neither is up and running, but will be in the coming weeks. Also in the next month, the Mustang will be going through a refit of sorts, having all of its suspension and brakes replaced, and then a general tune up. Suspension pieces are 35 years old, and rubber hoses and such all need replacing. I won't take up a lot more room here about that project, as these are words for a different forum
The M156 Crossfire will essentially be a Mercedes CLK63 in Crossfire clothing. As such, I have begun calling it the CF63, to differentiate it from all the other Crossfires around here (there are 6 of them here at this moment, not all ours). So, from here out, if CF63 is mentioned, you'll know why. The "old" car is called CF55 for similar reasons.
OK, now with that out of the way, I can mention progress on the CF63. Wiring is still the name of the game. While the car will most closely resemble a CLK63, there are some chief differences. First, the CF63 is a 2 door/2 seat coupe vs a 2 door/4 seat cabriolet. There are two power windows, not 4. The CF63 will use an aftermarket Android radio, not the full COMAND system with two different remote CD changers, and a host of other equipment requiring the fiber optic MOST network. The trunk is a liftgate hatch, unpowered with a mechanical latch. The CF63 is currently planned to retain the pneumatic central locking pump (called PSE in Mercedes parlance) vs the electric solenoid locks of the CLK. The CF63 will have the electronic HVAC system of the CLK. There are other differences. The CF63 will not feature a standard floor shifter, as all Crossfires and CLKs have, but rather will use a column mounted shifter from a W164 (ML-class). The seat controllers are also ML-class. Headlamps will be Crossfire halogen, but controlled by the Front Sensor Acquisition Module (SAM) from the CLK. Same with the tail lamps. So, why do this? In short, the desire for the CF63 is to be able to leverage as many modern conveniences as possible, while retaining the classic look and feel of the Crossfire. There are other ways to do this, as evidenced by the CF55, but I wanted to take this car much farther. And it will get there.
Wiring. There's a lot of it. About 85% of the original wiring in the car has been either clipped out, or abandoned in place. Why abandon it? Usually it is because there are a few wires that are part of a bundle that are no longer used, but too much trouble to unwrap an entire sub-harness to remove them. Easier to clip them off at both ends, and bypass them with the modern setup. For instance, the Front SAM will control the headlamps. Wiring for them in the Crossfire runs from the headlamp switch down under the carpet, to the left side fusebox, and then out to the rest of the car. In the SAM architecture, those wires run from the SAM (which will live in the front left engine bay fusebox) to the headlamps. The headlamp switch communicates with the Front SAM, which then runs the lamps. One upside to this is that the number of high amperage circuits inside the car are reduced, which in turn reduces the threat of a dash fire, as we have seen from some Crossfires as of late. Importantly, the Front SAM takes care of how the lamps are run, and when, which helps prevent dead batteries from lamps being left on, or other features such as automatically turning the headlamps on when it gets dark, or the wipers are on. All those little things modern cars do that we like. Sure, turning the head lights on is not a big deal, but again, looking for the total package of making the car modern. Eventually this car will have automatic speed control wipers (which if you have driven a newer Mercedes, you can appreciate), Distronic (adaptive cruise control), and more. This more or less necessitates the modern electronic architecture that can be added this way.
To that end, wiring at the rear corners of the engine bay are getting complete makeovers. Wherever original wiring can be used, it has been, and then a new "overlay" wiring harness has been created, running across the engine bay, parallel to the original one. All new wiring is being wrapped in proper cloth tape, and closely resembles OEM wiring, so it stays hidden. A few wiring changes were needed to the ESP module wiring, mainly adding a few wires for features needed by the CLK63 architecture, but amazingly the ESP needed very little in the way of wiring to be compatible with the CLK version ESP that will be swapped in. Fortunately, the ESP itself is a 1:1 replacement, and will be easy. As the car will have the 6 piston CLK55 front brakes and 4 piston rears, it was decided to have an ESP with matching programming to go along with them. That will likely get swapped a little later down the line.
In the shorter run, the right side engine bay box, which contains the RCM, BCM and ME2.8 ECU needed to be overhauled. None of that equipment would be reused, so all of it was removed, and unnecessary wiring along with it. In place will be the newer ME9.7 ECU, a FPCU (fuel pump controller) and a relay to run the coolant pump for the water/oil cooler. M156 engines need a lot of oil cooling. All of the M156 cars run a large oil cooler that is roughly the size of the SRT6 heat exchanger. Most of them also have a small radiator oil cooler with a 9" fan in the right side fender well. There simply isn't room for it in this car, so instead will run a water to oil cooler from an ML63. This looks like the oil cooler you see on an SRT6, but it isn't mounted to the engine. It also uses the same water pump that the SRT6 uses to push water through the cooler when needed. The ME9.7 controls the pump via the relay. The FPCU is a new one for us. Rather than run the fuel pump full tilt with a relay, and then have a mechanical regulator (as the Crossfire does at the fuel filter), the FPCU varies the speed of the fuel pump, and under low loads, slows it down, and at high loads, speeds it up. This concept was first applied to the SL55, and then spread through all of the M156 cars that came later. Indeed, most all new cars on the road employ this strategy. See? We're going modern here!
If you have read through that wall of text, don't worry, some pics are coming!
First, we still have messes, but they are getting more manageable by the day. Compared to the last post, this is getting a little neater. Still unwrapped wires all around, but the layouts are coming together. Here we see the ECU box starting to take shape. The F2 connector (body side connector) for the ECU is 100% complete, and you see it connected to the ME9.7 ECU, which fits like a glove in the box. Above it you see the FPCU, and the coolant pump relay. The wires you see are left there to interface to the engine wiring harness, which we'll get to when the engine is installed.
Next, we move to the old fusebox. The Front SAM is sort of jammed in there at the moment. We have a plan on how to neaten that up, but will require a little bit of CAD and some 3D printing. When done, we'll have an OEM look.
Moving to the doors, believe it or not, we need computers there, too. Each door will receive a door control module (DCM). The DCM controls a number of things, including window and mirror. In the CLK, it also controlled the seats (buttons were on the door panels), door locks, and more. We are only using the mirror and window functions at the moment. In the more modern setup, the window motors have sensors that know the position of the window. This allows auto down and auto up of the window. It is also a safety, in that if something gets caught in the window as it is going up, it will stop and go back down. Hopefully not an issue here, but good to know it is there. The motor swap was dead simple. Pull the motor out of the CLK window regulator and screw it into the Crossfire assembly. Piece of cake! The door module in the CLK is mounted to the interior of the door shell, in a purpose made recess. It is both a solid place to mount, and keep it dry. This recess is non-existent in the Crossfire, so improvisation was the name of the game. Holes were drilled in the mountings of the DCM and the door, and it is essentially resting on the bottom of the cutout, and secured with zip ties. In an effort to keep it dry it was placed as inboard as possible, but also plastic was cut as an umbrella of sorts over the module to help shield it. Have done similar in other cars with good results. This rather unimpressive picture hides the true genius of the installation! Plastic flap down (there is plastic over the top and rear that does not move, too) Lifting the flap to see the wiring
This past week, power was put to the car for the first time. This picture confirms operation of the Front and Rear SAMs and the headlamp switch:
It's not much, but you get to see that the car lights up without catching fire, which is always an amazing thing when you take on projects like this!
Next up we turned the key to see what else might work, and I was greeted to warnings on the instrument cluster, but still success!
Lots more to sort through, but at least we see of signs of life. Even the gas gauge is working!
Not shown is the HVAC (AAC) system also lit up, and the fan started running immediately, which is excellent. More pics and details to come. This rather small looking progress is actually a huge accomplishment, and moves this project down the field immensely. Coming up will be the wrap up of the wiring, including making it look tidy everywhere. After that, will move into modifying the front core support to move the radiator forward, just like was done on the CF55. Adding the oil coolers after that, and moving ever closer towards engine installation. There are a few surprises that have not been announced in store, so stay tuned!
01 June 2026:
Realize it has been a minute since there was an update. Lot of changes in the garage where the M156 Crossfire is being parked. First off, the "CF55" (M113K Crossfire) sold a little while back, and that allowed us to move our 1991 Ford Mustang LX 5.0 out from against the wall where it has been stored under a car cover for 23 years, and prepare it to be back on the road. Nothing at all wrong with the Mustang, other than it has just sat for over two decades, but as it has been inside, under a car cover, it is in great condition. That space it is in will not go to waste, as we moved in a Bridgeport EZ-Trak Series 1 mill, and a Monarch 10EE lathe in that space. Neither is up and running, but will be in the coming weeks. Also in the next month, the Mustang will be going through a refit of sorts, having all of its suspension and brakes replaced, and then a general tune up. Suspension pieces are 35 years old, and rubber hoses and such all need replacing. I won't take up a lot more room here about that project, as these are words for a different forum
The M156 Crossfire will essentially be a Mercedes CLK63 in Crossfire clothing. As such, I have begun calling it the CF63, to differentiate it from all the other Crossfires around here (there are 6 of them here at this moment, not all ours). So, from here out, if CF63 is mentioned, you'll know why. The "old" car is called CF55 for similar reasons.
OK, now with that out of the way, I can mention progress on the CF63. Wiring is still the name of the game. While the car will most closely resemble a CLK63, there are some chief differences. First, the CF63 is a 2 door/2 seat coupe vs a 2 door/4 seat cabriolet. There are two power windows, not 4. The CF63 will use an aftermarket Android radio, not the full COMAND system with two different remote CD changers, and a host of other equipment requiring the fiber optic MOST network. The trunk is a liftgate hatch, unpowered with a mechanical latch. The CF63 is currently planned to retain the pneumatic central locking pump (called PSE in Mercedes parlance) vs the electric solenoid locks of the CLK. The CF63 will have the electronic HVAC system of the CLK. There are other differences. The CF63 will not feature a standard floor shifter, as all Crossfires and CLKs have, but rather will use a column mounted shifter from a W164 (ML-class). The seat controllers are also ML-class. Headlamps will be Crossfire halogen, but controlled by the Front Sensor Acquisition Module (SAM) from the CLK. Same with the tail lamps. So, why do this? In short, the desire for the CF63 is to be able to leverage as many modern conveniences as possible, while retaining the classic look and feel of the Crossfire. There are other ways to do this, as evidenced by the CF55, but I wanted to take this car much farther. And it will get there.
Wiring. There's a lot of it. About 85% of the original wiring in the car has been either clipped out, or abandoned in place. Why abandon it? Usually it is because there are a few wires that are part of a bundle that are no longer used, but too much trouble to unwrap an entire sub-harness to remove them. Easier to clip them off at both ends, and bypass them with the modern setup. For instance, the Front SAM will control the headlamps. Wiring for them in the Crossfire runs from the headlamp switch down under the carpet, to the left side fusebox, and then out to the rest of the car. In the SAM architecture, those wires run from the SAM (which will live in the front left engine bay fusebox) to the headlamps. The headlamp switch communicates with the Front SAM, which then runs the lamps. One upside to this is that the number of high amperage circuits inside the car are reduced, which in turn reduces the threat of a dash fire, as we have seen from some Crossfires as of late. Importantly, the Front SAM takes care of how the lamps are run, and when, which helps prevent dead batteries from lamps being left on, or other features such as automatically turning the headlamps on when it gets dark, or the wipers are on. All those little things modern cars do that we like. Sure, turning the head lights on is not a big deal, but again, looking for the total package of making the car modern. Eventually this car will have automatic speed control wipers (which if you have driven a newer Mercedes, you can appreciate), Distronic (adaptive cruise control), and more. This more or less necessitates the modern electronic architecture that can be added this way.
To that end, wiring at the rear corners of the engine bay are getting complete makeovers. Wherever original wiring can be used, it has been, and then a new "overlay" wiring harness has been created, running across the engine bay, parallel to the original one. All new wiring is being wrapped in proper cloth tape, and closely resembles OEM wiring, so it stays hidden. A few wiring changes were needed to the ESP module wiring, mainly adding a few wires for features needed by the CLK63 architecture, but amazingly the ESP needed very little in the way of wiring to be compatible with the CLK version ESP that will be swapped in. Fortunately, the ESP itself is a 1:1 replacement, and will be easy. As the car will have the 6 piston CLK55 front brakes and 4 piston rears, it was decided to have an ESP with matching programming to go along with them. That will likely get swapped a little later down the line.
In the shorter run, the right side engine bay box, which contains the RCM, BCM and ME2.8 ECU needed to be overhauled. None of that equipment would be reused, so all of it was removed, and unnecessary wiring along with it. In place will be the newer ME9.7 ECU, a FPCU (fuel pump controller) and a relay to run the coolant pump for the water/oil cooler. M156 engines need a lot of oil cooling. All of the M156 cars run a large oil cooler that is roughly the size of the SRT6 heat exchanger. Most of them also have a small radiator oil cooler with a 9" fan in the right side fender well. There simply isn't room for it in this car, so instead will run a water to oil cooler from an ML63. This looks like the oil cooler you see on an SRT6, but it isn't mounted to the engine. It also uses the same water pump that the SRT6 uses to push water through the cooler when needed. The ME9.7 controls the pump via the relay. The FPCU is a new one for us. Rather than run the fuel pump full tilt with a relay, and then have a mechanical regulator (as the Crossfire does at the fuel filter), the FPCU varies the speed of the fuel pump, and under low loads, slows it down, and at high loads, speeds it up. This concept was first applied to the SL55, and then spread through all of the M156 cars that came later. Indeed, most all new cars on the road employ this strategy. See? We're going modern here!
If you have read through that wall of text, don't worry, some pics are coming!
First, we still have messes, but they are getting more manageable by the day. Compared to the last post, this is getting a little neater. Still unwrapped wires all around, but the layouts are coming together. Here we see the ECU box starting to take shape. The F2 connector (body side connector) for the ECU is 100% complete, and you see it connected to the ME9.7 ECU, which fits like a glove in the box. Above it you see the FPCU, and the coolant pump relay. The wires you see are left there to interface to the engine wiring harness, which we'll get to when the engine is installed.
Next, we move to the old fusebox. The Front SAM is sort of jammed in there at the moment. We have a plan on how to neaten that up, but will require a little bit of CAD and some 3D printing. When done, we'll have an OEM look.
Moving to the doors, believe it or not, we need computers there, too. Each door will receive a door control module (DCM). The DCM controls a number of things, including window and mirror. In the CLK, it also controlled the seats (buttons were on the door panels), door locks, and more. We are only using the mirror and window functions at the moment. In the more modern setup, the window motors have sensors that know the position of the window. This allows auto down and auto up of the window. It is also a safety, in that if something gets caught in the window as it is going up, it will stop and go back down. Hopefully not an issue here, but good to know it is there. The motor swap was dead simple. Pull the motor out of the CLK window regulator and screw it into the Crossfire assembly. Piece of cake! The door module in the CLK is mounted to the interior of the door shell, in a purpose made recess. It is both a solid place to mount, and keep it dry. This recess is non-existent in the Crossfire, so improvisation was the name of the game. Holes were drilled in the mountings of the DCM and the door, and it is essentially resting on the bottom of the cutout, and secured with zip ties. In an effort to keep it dry it was placed as inboard as possible, but also plastic was cut as an umbrella of sorts over the module to help shield it. Have done similar in other cars with good results. This rather unimpressive picture hides the true genius of the installation!
Plastic flap down (there is plastic over the top and rear that does not move, too)
Lifting the flap to see the wiring
This past week, power was put to the car for the first time. This picture confirms operation of the Front and Rear SAMs and the headlamp switch:
It's not much, but you get to see that the car lights up without catching fire, which is always an amazing thing when you take on projects like this!
Next up we turned the key to see what else might work, and I was greeted to warnings on the instrument cluster, but still success!
Lots more to sort through, but at least we see of signs of life. Even the gas gauge is working!
Not shown is the HVAC (AAC) system also lit up, and the fan started running immediately, which is excellent. More pics and details to come. This rather small looking progress is actually a huge accomplishment, and moves this project down the field immensely. Coming up will be the wrap up of the wiring, including making it look tidy everywhere. After that, will move into modifying the front core support to move the radiator forward, just like was done on the CF55. Adding the oil coolers after that, and moving ever closer towards engine installation. There are a few surprises that have not been announced in store, so stay tuned!
Re: M156 Into a Crossfire - Journal
