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1988 BMW M5, 1989 BMW M3, 1979 Mercedes 450 SEL 6.9, 2006 SL55 AMG w/ P30 Performance Pack
Limp Mode After Replacing Suspension and Steeting Components
Hello,
I recently replace all my control arms/ ball joints and tie rods on my SL55. I had some weird squeaks and I figured it was time. I got all the proper tools and wrenched all weekend! It was a PITA even with correct tools. Having a motorcycle jack really helps support the suspension for this job. It cradles the disc and rotors! It didn't help the weather was over 100F and humid as hell.
Took the car for a test drive and she is in limp mode with no faults or codes found with my STAR! I obviously disturbed the alignment after replacing my shot inner and outer tie rods. I did a test only alignment using string etc. just enough to drive it 3 miles to the alignment shop. I also disturbed the ABS speed sensors. I tried doing the reset by turning the steering wheel lock to lock, disconnected the battery (one year new) and rechecked and cleaned the ABS sensors.
After disconnecting the battery, I did finally get a "ESP not Available see owner's manual in the dash." Maybe I'll get more info. after hooking up to STAR again. (which found zero faults with all sensors associated with the front end initially) If anyone has any suggestions from this type of experience it would be greatly appreciated.
18 year old 130K shock arms were still in amazing shape. Bushings still intact. Lower ball joint and thrust arms were original and were needing of replacement. Happiness are new tie rod boots!
Last edited by m5zealot; Aug 29, 2022 at 10:49 PM.
Reason: spelling
Did you do a full quick scan? If so, were all the modules communicating? I don't believe it is possible for it to go into a limp mode without throwing codes. The ESP error will always come up when you disconnect the rear battery, so that is not related.
What is 'limp mode' in this case, not shifting, limited throttle, or something else?
1988 BMW M5, 1989 BMW M3, 1979 Mercedes 450 SEL 6.9, 2006 SL55 AMG w/ P30 Performance Pack
Originally Posted by MikeJ65
Did you do a full quick scan? If so, were all the modules communicating? I don't believe it is possible for it to go into a limp mode without throwing codes. The ESP error will always come up when you disconnect the rear battery, so that is not related.
What is 'limp mode' in this case, not shifting, limited throttle, or something else?
I did a full scan and all modules were communicating. Limp mode behavior is: won’t go faster than 2 mph going forward - limited throttle. Traction light flickers too. Seems to be stuck in 2nd gear just like when my SBC timed out a few years ago. It goes in reverse fine. Throttle is fine in neutral and can rev engine up to 3,000 rpm. Last time I tried to drive it after charging battery I thought I felt some binding or faint clunks in the chassis. But can’t be sure.
I recheck my work again this morning. All nuts are torqued correctly to spec. Pulled out the ABS sensors again and visually checked them for damage. Charging battery again after leaving it disconnected all night. Btw - I did get “ESP not available” message in the dash yesterday after plugging the battery back. Just a note. I have replaced my batteries once and have disconnected them many times the last year to do other PM and never saw the ESP light come on. Only warning I got battery related was once when the heat here killed the main battery. (Some features may not be available warning)
Thanks for relying and I’ll post more findings later today.
I'm struggling to think what you may have disconnected or damaged and what could possibly cause this without throwing codes. Did you deactivate SBC to do your work? Is it reactivated?
I would start by going to the ESP module and checking wheel speeds as you drive. If they look okay, go to the ESP sensors and the engine CAN data. Maybe the ESP thinks that the car is losing traction or in a skid and is trying to save it. Also reset the steering angle sensor by going lock to lock.
Also, you probably know this, but if the quick scan shows a ! in the last column and no info like p/n on a line, that means that DAS failed to connect to that module. DAS will show all of the mandatory modules whether it can communicate with them or not.
1988 BMW M5, 1989 BMW M3, 1979 Mercedes 450 SEL 6.9, 2006 SL55 AMG w/ P30 Performance Pack
Got it thanks! I'm still learning my STAR since I just got it in the spring. I disconnected the battery before starting any work so - no I did not deactivate SBC. I'm just perplexed at this issue. I have replaced rotors, calipers - upper shock pads and many more maintenance items since I got the car in 2017 w/ 65K well maintained miles and have never run into any issues resulting in limp mode. The only electronics disturbed were the speed sensors and plunger sensors on the shocks.
Note: I did forget to plug one of the plunger sensors back in when I started the car for the first time and caused an ABC warning. Duh. Who knows, this may have started a cascading effect. Thanks.
1988 BMW M5, 1989 BMW M3, 1979 Mercedes 450 SEL 6.9, 2006 SL55 AMG w/ P30 Performance Pack
Originally Posted by MikeJ65
I'm struggling to think what you may have disconnected or damaged and what could possibly cause this without throwing codes. Did you deactivate SBC to do your work? Is it reactivated?
I would start by going to the ESP module and checking wheel speeds as you drive. If they look okay, go to the ESP sensors and the engine CAN data. Maybe the ESP thinks that the car is losing traction or in a skid and is trying to save it. Also reset the steering angle sensor by going lock to lock.
Also, you probably know this, but if the quick scan shows a ! in the last column and no info like p/n on a line, that means that DAS failed to connect to that module. DAS will show all of the mandatory modules whether it can communicate with them or not.
Finally got some error codes off the SBC module after having the battery disconnected overnight. Along with traction warning light - the roll bar icon is flickering intermittently too in park. Systems are definitely thinking I'm doing donuts in a parking lot! Going to do more test. BTW - my SBC was replaced under extended warranty by MBUSA after it timed out on my 2 years ago. Not exceeded 3 million actuations yet.
Last edited by m5zealot; Aug 31, 2022 at 05:39 PM.
Reason: deletion of picture
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