Hoping that someone very familiar with ABC problems can help me.
After pro-actively replacing the three ABC accumulators (and dampener) I needed to recalibrate the ABC system. The Level and Load calibrations were successful, but the Plunger Travel calibration is kicking me. I suspect its because when the car is raised to the max, the rear plunger values are at 6 and not at 0 (as they are in the front). Here are the details:
2004 SL600 with 28,000 miles
ABC worked perfectly before starting this project.
Using both the MB Star/DAS and top-end Autel scanners. Same results and values on both.
Rodeo works fine, system pressure is 191 Bar.
Both Level and Load calibrations were successful. (Ensures ride height sensors are working.)
The ABC system gives me the code for "Plunger travel not calibrated" and therefore goes into limp mode when I drive.
When the rear accumulator was replaced, many lines were disconnected and some were highly pressurized.
After running the Plunger Travel calibration I always get the error "Signal of plunger travel sensor is not within tolerance".
My understanding is that the test ensures that each corner's plunger values can go between 0 and 99. The fonts do, but both rears go between 99 and only 6.
Wondering if I introduced air into the dead-end struts, I bled a couple ounces of fluid out of each rear one. This made no difference to the values. I use the Level calibration step to raise the rears to their max and then read the plunger values.
Since the car is sitting above a hoist, I raised the car, "lifted" the rears and still can only get the rear plunger values down to 6.
I see nothing that is limiting rear suspension travel.
As this point, I'm hoping someone can suggest a solution.
I'm currently thinking:
* Bleed the rears more, perhaps with engine even running. (I've done 30 second rodeos several times.)
* Go back to the old rear accumulator
* Try a different rear valve block; I have a newly rebuilt one
Since the car was working perfectly, my thinking is:
* The rear plunger travel sensors are OK; also because they reach the exact same value
* Perhaps something has "worn" since the last calibration was done, which might have been many years ago. (I've had the car for 3 years and this is the first ABC issue.)
So I know a fair amount about the ABC system, but not enough to try things like setting the valve block solenoids, looking at their current and such. If that might help, please tutor me.
BTW - what started all this is that I swapped in a refreshed AMG engine to replace the original engine. I will document this in detail after I solve this ABC problem.
Thank you.
After pro-actively replacing the three ABC accumulators (and dampener) I needed to recalibrate the ABC system. The Level and Load calibrations were successful, but the Plunger Travel calibration is kicking me. I suspect its because when the car is raised to the max, the rear plunger values are at 6 and not at 0 (as they are in the front). Here are the details:
2004 SL600 with 28,000 miles
ABC worked perfectly before starting this project.
Using both the MB Star/DAS and top-end Autel scanners. Same results and values on both.
Rodeo works fine, system pressure is 191 Bar.
Both Level and Load calibrations were successful. (Ensures ride height sensors are working.)
The ABC system gives me the code for "Plunger travel not calibrated" and therefore goes into limp mode when I drive.
When the rear accumulator was replaced, many lines were disconnected and some were highly pressurized.
After running the Plunger Travel calibration I always get the error "Signal of plunger travel sensor is not within tolerance".
My understanding is that the test ensures that each corner's plunger values can go between 0 and 99. The fonts do, but both rears go between 99 and only 6.
Wondering if I introduced air into the dead-end struts, I bled a couple ounces of fluid out of each rear one. This made no difference to the values. I use the Level calibration step to raise the rears to their max and then read the plunger values.
Since the car is sitting above a hoist, I raised the car, "lifted" the rears and still can only get the rear plunger values down to 6.
I see nothing that is limiting rear suspension travel.
As this point, I'm hoping someone can suggest a solution.
I'm currently thinking:
* Bleed the rears more, perhaps with engine even running. (I've done 30 second rodeos several times.)
* Go back to the old rear accumulator
* Try a different rear valve block; I have a newly rebuilt one
Since the car was working perfectly, my thinking is:
* The rear plunger travel sensors are OK; also because they reach the exact same value
* Perhaps something has "worn" since the last calibration was done, which might have been many years ago. (I've had the car for 3 years and this is the first ABC issue.)
So I know a fair amount about the ABC system, but not enough to try things like setting the valve block solenoids, looking at their current and such. If that might help, please tutor me.
BTW - what started all this is that I swapped in a refreshed AMG engine to replace the original engine. I will document this in detail after I solve this ABC problem.
Thank you.
After more diagnosis and parts, I still cannot get the ABC Plunger Travel to calibrate successfully, putting the ABC into limp mode with maximum height.
Since my last post, I have bleed the rears with the engine running (showering me in fluid), replaced the rear valve block, removed and inspected the rear strut plunger sensors.
I even replaced the ABC computer module. This initially showed no ABC codes, but the raise/lower button didn't work (stayed lit) and on first driving it went into limp mode again.
I did learn that the ABC valve block sold by ebay seller "Autohubshop" seems to work perfectly. Rear raises and lowers exactly as before and the ABC Level and Load calibrations succeeded as before. Rodeo also works properly as before. Note that Rodeo does not raise the rear as much as the calibrations.
Again, I suspect the Plunger Travel calibration fails because at full raise, the rear plunger values go only to 6 and like are supposed to go to 0, as do the front values.
Replacing the rear valve body is a bit of a process, keeping the hydraulic lines untangled and re-installing in the correct order. I found it easier to first remove the large accumulator; also to completely remove the short line from the valve block to the smaller return accumulator.
I suspect some people might disconnect the "quick connect" lines, but since these contain now 20 year old o-rings, I didn't want to take a chance with tearing a likely unique o-ring.
Unlike some of the YouTube videos on how to access the rear struts by removing all the rear carpeting, I found it trivial by first pulling the side carpet out from middle section (with a trim tool) and then cutting a slit over the rear strut. When the carpeting is pushed back, the slits are barely visible. Another YouTuber cuts a round hole over the strut and then covers it later with a disk; IMHO that is much uglier and noticeable than just a slit in the carpeting.
So, I am learning ever more about the ABC system, but it is also frustrating that the engine swap and preventative accumulator replacements has led to this.
My likely next step is to level the suspension and install yet another ABC computer module; maybe it will be happy with the ride height and plunger travel values it sees, and not require a calibration.
After that, it seems my remaining option is to replace the rear struts and hope that does it.
Again, if anyone has gone this far into ABC diagnostics, I'm all ears.
Since my last post, I have bleed the rears with the engine running (showering me in fluid), replaced the rear valve block, removed and inspected the rear strut plunger sensors.
I even replaced the ABC computer module. This initially showed no ABC codes, but the raise/lower button didn't work (stayed lit) and on first driving it went into limp mode again.
I did learn that the ABC valve block sold by ebay seller "Autohubshop" seems to work perfectly. Rear raises and lowers exactly as before and the ABC Level and Load calibrations succeeded as before. Rodeo also works properly as before. Note that Rodeo does not raise the rear as much as the calibrations.
Again, I suspect the Plunger Travel calibration fails because at full raise, the rear plunger values go only to 6 and like are supposed to go to 0, as do the front values.
Replacing the rear valve body is a bit of a process, keeping the hydraulic lines untangled and re-installing in the correct order. I found it easier to first remove the large accumulator; also to completely remove the short line from the valve block to the smaller return accumulator.
I suspect some people might disconnect the "quick connect" lines, but since these contain now 20 year old o-rings, I didn't want to take a chance with tearing a likely unique o-ring.
Unlike some of the YouTube videos on how to access the rear struts by removing all the rear carpeting, I found it trivial by first pulling the side carpet out from middle section (with a trim tool) and then cutting a slit over the rear strut. When the carpeting is pushed back, the slits are barely visible. Another YouTuber cuts a round hole over the strut and then covers it later with a disk; IMHO that is much uglier and noticeable than just a slit in the carpeting.
So, I am learning ever more about the ABC system, but it is also frustrating that the engine swap and preventative accumulator replacements has led to this.
My likely next step is to level the suspension and install yet another ABC computer module; maybe it will be happy with the ride height and plunger travel values it sees, and not require a calibration.
After that, it seems my remaining option is to replace the rear struts and hope that does it.
Again, if anyone has gone this far into ABC diagnostics, I'm all ears.
With more experimentation I finally got my ABC system working.
Thinking about what else changed with the engine swap, I swapped in the AMG ECU. I "reset/virginized" the ECU and had it learn the security/key codes so that the engine would start. I did notice that the VIN did not seem to reset and that the ABS module complained about that. (Perhaps I could have reset the ABS code). So when driving I would get continuous ABS and ABC warnings with the suspension in a very high (limp mode?) setting.
Since my earlier post today, I leveled the car with the scanner and then installed the original ECU and another (fresh from Ebay) ABC computer module. After resetting various ABC codes, including modules don't match, everything seems to be working. I can drive it around the block without any ABC or ABS warnings.
To experiment further, I re-installed the original ABC computer module. It still had three calibration codes and they would not clear. With my restricted plunger travel, I see no way to clear these codes. So I went back to the "new" working ABC computer module.
My current hypothesis is that the combination of the engine swap, which caused a brief loss of ABC pressure, and the replacement of the accumulators caused serious codes in the ABC module which can only be cleared by a successful calibration of the Level, Load and Plunger Travel. I guess my rear struts can no longer go through their full motion which prevents the calibration from working. The "new" ABC module had no codes set and saw no reason to set serious codes.
I don't yet understand why the "new" ABC module wouldn't work with my AMG ECU. A wild guess is that if the ABS system isn't working it puts the ABC system into limp mode. Obviously I need to get the AMG ECU working before I seriously drive the car.
The crazy complexity of the ABC system, including my problems described in the thread, may encourage more people to switch to coil-overs. At least you won't ever get stranded with an ABC suspension failure.
Thinking about what else changed with the engine swap, I swapped in the AMG ECU. I "reset/virginized" the ECU and had it learn the security/key codes so that the engine would start. I did notice that the VIN did not seem to reset and that the ABS module complained about that. (Perhaps I could have reset the ABS code). So when driving I would get continuous ABS and ABC warnings with the suspension in a very high (limp mode?) setting.
Since my earlier post today, I leveled the car with the scanner and then installed the original ECU and another (fresh from Ebay) ABC computer module. After resetting various ABC codes, including modules don't match, everything seems to be working. I can drive it around the block without any ABC or ABS warnings.
To experiment further, I re-installed the original ABC computer module. It still had three calibration codes and they would not clear. With my restricted plunger travel, I see no way to clear these codes. So I went back to the "new" working ABC computer module.
My current hypothesis is that the combination of the engine swap, which caused a brief loss of ABC pressure, and the replacement of the accumulators caused serious codes in the ABC module which can only be cleared by a successful calibration of the Level, Load and Plunger Travel. I guess my rear struts can no longer go through their full motion which prevents the calibration from working. The "new" ABC module had no codes set and saw no reason to set serious codes.
I don't yet understand why the "new" ABC module wouldn't work with my AMG ECU. A wild guess is that if the ABS system isn't working it puts the ABC system into limp mode. Obviously I need to get the AMG ECU working before I seriously drive the car.
The crazy complexity of the ABC system, including my problems described in the thread, may encourage more people to switch to coil-overs. At least you won't ever get stranded with an ABC suspension failure.
