SL/R230: Stubborn ABC problem with C1525-032 code and my solution
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Joined: Sep 2021
Posts: 546
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From: Ann Arbor, MI
2004 SL600
Stubborn ABC problem with C1525-032 code and my solution
Last year during an engine swap, I decided it was a good time to perform preventative maintenance on the ABC system since it was already drained and disconnected.
I replaced the three accumulators, pressure dampener, rear valve block, filter and fluid.
After re-assembly and engine startup, I un-surprisingly got the Red ABC warning and related codes. While the Up/Down buttons did not work, I was able to perform a rodeo with a scanner. When done the car was level, but as soon as I drove it the rear shot up to max level. I first suspected the mechanical level sensors since at least the front ones were disconnected for the engine swap. I even replaced them and that was not it.
Checking codes more carefully, I had a C1525-032 which is "Calibration of plunger travel sensors has not been successfully performed". It could not be cleared.
By now I had learned how to use Star/DAS or my Autel IM608 to read both the mechanical level sensor voltages and percentages and the strut plunger percentages.
So, under "ABC control unit -> Adaptations" I tried the "Calibrate plunger travel" function which moves each corner strut through its full range.
The fronts strut went down to 0% and up to 100% just fine. However, the rears went down to 0% but up to only 98% and that caused the calibration to fail. Damn.
I put the car up on a hoist to perhaps facilitate full extension, but it still only extended to 98%. I made sure nothing in the suspension was limiting travel.
Next, I accessed the tops of the rear struts and removed the internal travel sensors ( long sticks) and they looked perfect with no corrosion or dirt. I did not want to send the rear struts out for a rebuild,
Now suspecting a module problem, I ordered a replacement ABC module from ebay for only $60. My part number was 032-545-54-32. After installing it and clearing some "soft" codes, the ABC system worked perfectly.
Granted the left rear sits 3/4" lower than the right, but I'm hesitant to try a re-calibration, fearing it might fail and set a hard code in another ABC module. (I already bought a 3rd ABC module from ebay just in case.)
There seems to be no limit to how many different ABC problems can occur. This is the story of my problem, perhaps rare, perhaps not, and my solution to it.
I replaced the three accumulators, pressure dampener, rear valve block, filter and fluid.
After re-assembly and engine startup, I un-surprisingly got the Red ABC warning and related codes. While the Up/Down buttons did not work, I was able to perform a rodeo with a scanner. When done the car was level, but as soon as I drove it the rear shot up to max level. I first suspected the mechanical level sensors since at least the front ones were disconnected for the engine swap. I even replaced them and that was not it.
Checking codes more carefully, I had a C1525-032 which is "Calibration of plunger travel sensors has not been successfully performed". It could not be cleared.
By now I had learned how to use Star/DAS or my Autel IM608 to read both the mechanical level sensor voltages and percentages and the strut plunger percentages.
So, under "ABC control unit -> Adaptations" I tried the "Calibrate plunger travel" function which moves each corner strut through its full range.
The fronts strut went down to 0% and up to 100% just fine. However, the rears went down to 0% but up to only 98% and that caused the calibration to fail. Damn.
I put the car up on a hoist to perhaps facilitate full extension, but it still only extended to 98%. I made sure nothing in the suspension was limiting travel.
Next, I accessed the tops of the rear struts and removed the internal travel sensors ( long sticks) and they looked perfect with no corrosion or dirt. I did not want to send the rear struts out for a rebuild,
Now suspecting a module problem, I ordered a replacement ABC module from ebay for only $60. My part number was 032-545-54-32. After installing it and clearing some "soft" codes, the ABC system worked perfectly.
Granted the left rear sits 3/4" lower than the right, but I'm hesitant to try a re-calibration, fearing it might fail and set a hard code in another ABC module. (I already bought a 3rd ABC module from ebay just in case.)
There seems to be no limit to how many different ABC problems can occur. This is the story of my problem, perhaps rare, perhaps not, and my solution to it.
