R350 suddenly showing tire pressure monitor/cruise control / SRS inoperative
02-17-2020, 05:35 PM
#1
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R350 suddenly showing tire pressure monitor/cruise control / SRS inoperative
2011 R350 Diesel
So been an interesting few days. a few days ago the tire pressure light went on and I thought I'll go buy costco and have them fix it. . then this morning the following items all are displaying warning:
Auxillary battery inoperative
Tire Pressure Monitor inoperative
Cruis Control Inoperative
SRS Malfunction (Front Right Needs Service)
AND
The rear view camera, front and rear parking sensors, and blind spots sensors are all not working
I have to believe that these are all related somehow. Could they all be driven by the Auxillary Battery problem?
Thanks!
So been an interesting few days. a few days ago the tire pressure light went on and I thought I'll go buy costco and have them fix it. . then this morning the following items all are displaying warning:
Auxillary battery inoperative
Tire Pressure Monitor inoperative
Cruis Control Inoperative
SRS Malfunction (Front Right Needs Service)
AND
The rear view camera, front and rear parking sensors, and blind spots sensors are all not working
I have to believe that these are all related somehow. Could they all be driven by the Auxillary Battery problem?
Thanks!
02-19-2020, 08:55 PM
#2
Super Member
bus communication issue. maybe to faulty voltage.. Check your alternator/batterr... Not just battery test but alternator current/load/ voltage test
Happened to me.. to a few others.
Happened to me.. to a few others.
03-04-2020, 02:17 PM
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Diagnosed as bad auxillary battery which it wasn't. . .looks like alternator. Took it to Autozone and battery checks out fine but their device said faulty alternator.
I have seen on other (non R class) that a bad voltage regulator will give similar behavior?
I have seen on other (non R class) that a bad voltage regulator will give similar behavior?
04-03-2020, 02:21 PM
#5
Senior Member
These cars like a good solid 13v+- power supply.
When alternator is suspect, be very very careful if ordering a replacement.
The ECU communicates withe the alternator's voltage regulator, in effect telling the VR
"I need more power" or "We're good now" - it goes beyond battery safety avoiding overcharging, to the point of letting the alternator freewheel unloaded to conserve fuel.
Mine (late 2007 manufactured R320) might have the same exact frame, but have a different pulley, power output, and communications protocol with the ECU than yours.
If your ECU can't communicate with/recognize the alternator, it won't turn off the dash light and may not be able to prevent overcharging, etc.
At a minimum, it will never be happy nor let you be happy.
Do not use a chain store re-manufactured unit, unless you're stranded on a small desert island.
The voltage regulators there come from China.
Ideally, pull the unit off, read the number and brand, and replace with the exact unit especially if it is OE
Mine was originally Valeo, and eventually I was able to find the exact same unit new.
For half the price of even a Bosch re-man... but that's another story.
When alternator is suspect, be very very careful if ordering a replacement.
The ECU communicates withe the alternator's voltage regulator, in effect telling the VR
"I need more power" or "We're good now" - it goes beyond battery safety avoiding overcharging, to the point of letting the alternator freewheel unloaded to conserve fuel.
Mine (late 2007 manufactured R320) might have the same exact frame, but have a different pulley, power output, and communications protocol with the ECU than yours.
If your ECU can't communicate with/recognize the alternator, it won't turn off the dash light and may not be able to prevent overcharging, etc.
At a minimum, it will never be happy nor let you be happy.
Do not use a chain store re-manufactured unit, unless you're stranded on a small desert island.
The voltage regulators there come from China.
Ideally, pull the unit off, read the number and brand, and replace with the exact unit especially if it is OE
Mine was originally Valeo, and eventually I was able to find the exact same unit new.
For half the price of even a Bosch re-man... but that's another story.
