Systems Shutting Down - RESOLUTION

[Behold81]

So I thought this would help anyone that might get this fault.

My E-Class 350 but I believe would be similar in other models started to shutdown my radio and then proceed to do 80% of all other systems.

The issue only starts once the ignition is fully on
The car also runs with no issues so I believe the Fuel Pump short is likely to be an old uncleared fault. But this might not be true.

The SRS alert came on and was permanent on my dash. (Think this is the case till it clears)

Normally its always the Comand system that shuts off first. Then the Presafe warning comes up on the dash and the rest of the systems fail to work.

Airscarf
Heated Seat
Vented Seat
Parktronic
Steering wheel controls
Heating system on minimal working
Intelligent light system
High beam does nothing
ODB2 often fails
Heated Rear windows and mirrors

Car had NO running issues and the following still worked:

AirCap
Roof
Windows
Dash Dials
MPG, Milometer still seems to calculate
Heating does run and adjust just low blowing
Mirrors Adjust and fold
Memory Seats and Steering Wheel

The problem got to the point that it rarely came back once failed, although I still got it that it can run for 30 mins+ no issues.

The Dash showed incorrect voltages 15v and as low as 7.5 and the car was charging fine at 14.66

The car showed NUMOROUS Faults about low voltage.

SRS - Supplemental restraint system (N2/10) (MB:2079011900)
Fault Code: 00B1CFF
Fault Explanation: : Fault: The squib for pyrofuse 'On-board electrical network line' has excessively low resistance.
PARK - Parking system (N62) (MB: 2129011500)
Fault Code: A10A00
Fault Explanation: Fault: The power supply in the system is too low. - No sub type information system undervoltage - no sub type information
ZAN - Audio/COMAND display (A40/8) (MB: 2129010500)
Fault Code: 00A10A
Fault Explanation: Fault: The power supply in the system is too low.
Fault Code: 00953D
Fault Explanation: Fault: Signal 'Low voltage differential' has an open circuit.
BSN - Battery sensor (B95), AS - Alarm siren (H3/1), IRS - Interior protection and tow-away protection (N26/6), Rear SAM - Rear signal acquisition and actuation module (N10/2), SIH/
SIB - Seat heater/seat ventilation (R13/1, R13/2, M18/9,M18/10) (MB: 2129012304)
Fault Code: A19116
Fault Explanation: Fault: The power supply of circuit 30g is outside the valid range. The limit value for electrical voltage has not been attained.
Fault Code: A10C16
Fault Explanation: Fault: The power supply is outside the valid range. The limit value for electrical voltage has not been attained.

These are just a Few of the codes I got. I did many diagnostics but finally took it to CommandOnline for investigation. Typically the issue NEVER happened while it was in for diag.....<Angry> but they still did a full wiring check and we spoke through thoughts. As the system was shutting down and not cutting out the F32 Relay was excluded from being the fault.

This put it to either the Rear Sam or the Negative battery lead. Due to cost and ease and assuming the rear sam was working as it should as it was telling equipment to shut down and thinking it was low on voltage I bought a Negative cable (with sensor) and replaced it. (10 mins max. Mostly finding your spanners!)

Once replaced instantly the Voltage read 14.7 on the dash not 15 and varied correctly on start up to the volt meter. I have driven it now for about 8-10 hours with not one failure. I hope this article helps some people if they get this fault.

Thanks

 

[Gbrowncls55]

Thanks
I have posted already about my car (sl350) which has similar problems on a random basis. Sometimes it will go for three weeks with no problems then do it everyday. It starts with the srs light not going off then after a mile or so the command shuts down and the wipers won't work. Sometimes it comes back sometimes not. Fault code says low or no voltage at connection 15. Like you it behaved perfectly when it went in to be sorted. Given its a pretty cheap and easy fix you did I will try that....you never know. Very interesting thanks for taking the time.

 

[Behold81]

Thanks
I have posted already about my car (sl350) which has similar problems on a random basis. Sometimes it will go for three weeks with no problems then do it everyday. It starts with the srs light not going off then after a mile or so the command shuts down and the wipers won't work. Sometimes it comes back sometimes not. Fault code says low or no voltage at connection 15. Like you it behaved perfectly when it went in to be sorted. Given its a pretty cheap and easy fix you did I will try that....you never know. Very interesting thanks for taking the time.

If the command is actually shutting down and not just turning off it could be the cause. My dash in engineering mode showed low voltage as the issues occurred.

I will dig out the part code for you. I have the newest version as apparently the old model was know to have issues.

 

[richard]

R230 SL350 will have a different way of measuring the battery voltage - (as it has 2 batteries). 1st thing to check is the main battery itself using a proper battery tester (as we did with car above) - this is especially likely on R230 SL..

R231 has one battery and does work like the W207, but the part numbers for the leads will be different as different lengths.

Richard

 

[Gbrowncls55]

Thanks Richard.Replaced main ( rear) battery, checked SAM'S by substitution and replaced fuse board so far. Considering EIS given the conection15 no or low voltage code. Not worth doing the main battery earth as above?

 

[Gbrowncls55]

Sorry thanks OP also......

 

[richard]

Gbrowncls55 - Id look at the 'Vehicle Power Supply' control unit next, It directly controls the circuit 15r/30 relay, and is the one that tells the car's various ECU to shut-down as power gets low

- on the car above (W212) the battery voltage is measured by a sensor on the ground cable (so thats why the cable was replaced, all one part), and reports the voltage to one of the SAMs, which then tells the car to shutdown. On R230 its all done in the control module I mention above.

R

 

[Gbrowncls55]

Thanks Richard most helpful. I'll update when I have investigated.

 

[Bobclive2]

I have recently disconnected the neg lead battery sensor on my 2012 c-class coupe, have checked with a multimeter across the battery and the charging voltages on idle and full load at 2000 revs, no overcharge at any point, max charge without sensor was 14.3 volts so it appears the alternator is in default mode. My reason for removing sensor was to disable stop/start, there are no warning lights on dash and everything works as it should other than brake hold which is of no issue to me. It appears the sensors main function is to ensure the auto stop/start function when on will always be able to restart car therefore once the sensor indicates what the ECU considers is a too low voltage stop/start is deactivated, this could just be through lack of use, to remedy this the main dealer will probably suggest replacing the expensive battery even though without stop/start this same battery would probably last some further years. With the sensor disconnected the alternator will charge the battery fully, when the sensor is in place the car will have a variable charge up to 15 volts and charging the battery up to about 80% leaving room for a further charge by overrun or brake regeneration therefore the battery is probably never fully charged. We are told that if a standard lead/acid battery is used the system will overcharge that battery and it will not last long, that appears to be only if the sensor is in place and allowed to charge that standard battery at 15 volts, as shown above the default charge is 14.3 volts or less.

A standard battery and alternator were fine before stop/start came along, cars still had the same equipment they have today in fact todays in car electrics are certainly more electrically efficient than they were even 10 years ago.


https://www.just-auto.com/analysis/...n-starter-motors-and-alternators_id86149.aspx
https://www.theicct.org/sites/defau...chnology Cost Analysis_StartStop Overview.pdf
Smart alternators and regenerative braking. - VW T4 Forum - VW T5 Forum
BMW Introduces Intelligent Alternator Control with Regenerative Braking; Reduces Fuel Consumption by About 4%

 

[richard]

The battery sensor is actually used for a lot more than that. Its used to detect low voltage whilst the car is running and shut down systems (in a pre-defined manner), and to monitor the battery when ignition is off, and if there is load after a certain time it also cuts power briefly to try and reset whichever control unit has not gone to sleep, i.e to prevent you coming back to a flat battery.

So, by disconnecting the battery sensor you stop Auto-stop start, but lose a lot of the other functionality which is designed to make sure you car always starts.

R