SMG Diagnostics and solutions

[NZ_M3]

This is a cut and paste advice I provided to a SMG owner here locally to help diagnose an issue he had. I thought it might be helpful to repeat this here. Majority of the info is just a regurgitation of what's already available on the net - but being fragmented I thought it might be a good idea to consolidate it some what. So here it is:

Don't over complicate the SMG system, it isn't actually that complex. It's basically just an electric pump with a pressure accumulator, bunch of hydraulic lines pushing fluids around and a few sensors telling the ECU what's going on.

The failure fashion tends to have a rough ranking in the following:

1. Infamous Salmon relay

2. hood switch

3. gear selection sensor

4. indent spring

5. temperature sensor (this has been known to cause accumulator like failures - because what it is basically doing is telling the SMG ecu that the pump fluid is overheating so it stops charging even when it isn't) - there's now really good resistor mods online that you can do to trick the system into never seeing an overheat. (More info about this follows)

6. SMG accumulator

7. SMG pump (there are businesses now overseas that do rewinds of these pumps) A few have attempted a self rewind DIY and failed, as apparently the brushes are quite special so to speak.

8. hydraulic lines.

There's an accumulator/pump test in the GT1 - those should be the first port of call to see if the tests pass or fail before you spend the money to replace the pump.


SMG Pump fluid temperature sensor - contrary to what BMW tells you, this sensor IS replaceable.

Item number 7 below:

BMW Part number (blue plug on the back of the sensor) 13-62-1-709-966

It's a Bosch sensor - Bosch part number 0 280 130 026

Or apparently the VDO one works also: Part number 805/9/1

Full sensor spec: (-40-+130C, NTC 2.5K@20C log curve +-5%, 1.0amp max M12x1.5mm, 19mm wrench, 25 NM installation torque)

The system throws a fit and shuts down the pump from recharge when temperature reaches above 80 degrees C - normal operating hydraulic fluid temp should be between 30 - 60degrees C. (It faults often because the bloody pump unit is right next to the engine block (clever design BMW !!!))

The SMG pump operates at 80Bar and starts recharging when it drops below 45bar. The accumulator has a volume of 150ccm (two cambers in the accumulator, separated by a piston, one side filled with nitrogen at 39bar). There's a pressure relief valve in the system that opens at 100bar. When reading the hydraulic pressure the voltage is always between 0.5v to 4.58v (0bar to 100bar respectively).

The resistor modification splices into a wire on the 18 pin plug tricking the system into thinking it's always within range. I believe the resister is suppose to be between 500ohm to 1K which will put it within range (most have reported the 680ohm works well even in very hot climate).


As you are introducing air to the hydraulic system, you WILL have to bleed the SMG system afterwards



The sensor is the right hand side one with the baby blue plug (below the dark blue dot)





Said sensor:






Resistor mod:



http://www.radioshack.com/product/index.js...;utm_medium=CSE





Wiring diagram ... (ignore the green arrow) Photo stolen from internet ...



You can also get to it from the top of the fuse box:

http://m3forum.net/m3forum/showthread.php?t=414499












Here are all possible inputs and programs from the program table in the SMG2 control module. (Credit to Josh - aka Hybrid on bimmersport in NZ)

0x22 gearbox temperature
0x27 hydraulic temperature
0x23 hydraulic pressure sensor evaluation
0x35 Lower level of pressure reached HE
0x36 Exceeding pressure range HE
0x33 bonnet switch evaluation while driving
0x34 bonnet switch evaluation while standstill
0x72 selector lever evaluation
0x24 selector angle (WW) position sensor evaluation
0x25 shift path (gear) position sensor evaluation
0x26 longitudinal acceleration evaluation
0x61 voltage supply
0x62 voltage supply sensor A
0x63 voltage supply sensor B
0x20 gearbox input speed evaluation
0x21 engine speed evaluation (sensor)
0x96 engine speed evaluation (CAN bus)
0x28 PLCD-sensor for position of clutch evaluation
0x80 Erroneous CAN message / CAN bus error
0x81 CAN error
0x91 wheel speed rear left evaluation
0x92 wheel speed rear right evaluation
0x93 wheel speed front left evaluation
0x94 wheel speed front right evaluation
0x95 wheel speed evaluation (several wheels)
0x97 operating break signals by CAN
0x9B Evaluation of gas pedal value via CAN
0x98 Evaluation of steering angle via CAN
0x99 Evaluation of lateral acceleration via CAN
0x9A Evaluation of longitudinal acceleration via CAN
0x90 door switch evaluation by CAN
0x13 Shift Lock control
0x14 starter enable
0x15 hydraulic pump relay control
0x16 light switch for reverse control
0x10 solenoid valve gear forward
0x11 solenoid valve gear backward
0x12 solenoid valve selector angle (WW)
0x17 solenoid valve clutch
0x50 gearbox controller internal error
0xB0 safety concept level 2, gearbox
0xB1 safety concept level 2, clutch
0xB2 safety concept level 3
0x53 gearbox adaptation
0x54 General Adaption
0x55 clutch adaptation
0x30 gear not changable
0x31 gear jump
0x32 Selector angle cannot be regulated
0x73 electrical consumers shutoff VA evaluation
0x74 program selector Plus evaluation
0x75 program selector Minus evaluation
0x76 steering wheel switch + evaluation
0x77 steering wheel switch - evaluation
0x37 Switching-on frequency of hydraulic unit
0x38 Switching-on time of hydraulic unit
0x39 Misuse of hydraulic unit
0x64 Power supply of solenoid valves for gear movement
0x65 Power supply of solenoid valves for clutch and selector angle
0x56 Bleeding
0x57 Aktions modi
0x78 Evaluation of ignition signal
0x51 Evaluation of ESTATE
0xB3 safety concept level 2, RAM
0xB4 safety concept level 2, input
0x3A not able to take out of gear
0x3B Clutch control
0x58 Adaption values of gearbox
0xFF Unknown error location

And all test programs that can be run (only using spcailist factory software (not shop software)

TESTPRG_NR TESTPRG_NAME DAUER TYP. DAUER MAX.
0x01 Bleeding clutch share cylinder/hydraulik line 2 min 2 min
0x02 Adapt clutch shipping point 5 sek 10 sek
0x03 Adapt clutch shipping values 1 min 2 min
0x04 Evaluate hydraulik pressure reserve 8 sek 30 sek
0x05 Bleeding gearbox actuator 16 min 16 min
0x06 Adapt current offset for selector angle (slot)
0x07 Completely adapt gerabox 2,30 min 3,0 min
0x08 Adapt offset for longitudinal accelration sensor 5 sek 20 sek
0x09 Position centre of shift path
0x0A Put into any gear
0x0B Adapt gearbox
0x0C Test centre of shift path and selector angle sensor
0x0D Adapt selector angle gear recognition
0x15 Produce start conditions for engine

[mattCSLnut]

Great bit of info Tom THANX very much for sharing
Now saved into my CSL info file for future reference

[Steve B]

That Bosch sensor is very widely used as well across a lot of car manufacturers..


Steve

[Mike R]

Could you put the symptoms beside each thing, so we know what to be looking for and what to check should the symptom arise?

Also, what causes the occasional mis-shift? I got three over the 'ring weekend - I "think" they were all 3rd to 4th. Haven't had any since and that makes around 5 or 6 in the 4k miles since I've had the car.

[adem.csl]

Originally Posted by Mike R

Could you put the symptoms beside each thing, so we know what to be looking for and what to check should the symptom arise?

Also, what causes the occasional mis-shift? I got three over the 'ring weekend - I "think" they were all 3rd to 4th. Haven't had any since and that makes around 5 or 6 in the 4k miles since I've had the car.

Mike i and 2 other members had same fault and believe it to be 4th gear synchromesh as me and another member have changed detent springs and recalibrated the ecu's.
If you scour the forum you will find a few many have had a new box due to this same fault!!
Group buy gearbox oil cooler kits i think??


Great write up on the smg pump i think this is whats causing a friends car to jump to neutral when extremely hot!thanx nz-m3

[CraigMillwardCroft]

Originally Posted by adem.csl

Mike i and 2 other members had same fault and believe it to be 4th gear synchromesh as me and another member have changed detent springs and recalibrated the ecu's.
If you scour the forum you will find a few many have had a new box due to this same fault!!
Group buy gearbox oil cooler kits i think??


Great write up on the smg pump i think this is whats causing a friends car to jump to neutral when extremely hot!thanx nz-m3

Are you going to fit the oil cooler kits for us

[Mike R]

I would be surprised if it was the synchro, as I would imagine it would be a far more regular occurrence (as surely once this was worn, it would do it all the time?). It only does it when hot, so I can only surmise it could be to do with the fluid getting hot and losing pressure and not quite having enough energy to engage the gear (which will eventually end up damaging the synchro as a by-product of the mis-shift?).

[cantfind1]

Originally Posted by Mike R

Could you put the symptoms beside each thing, so we know what to be looking for and what to check should the symptom arise?

Also, what causes the occasional mis-shift? I got three over the 'ring weekend - I "think" they were all 3rd to 4th. Haven't had any since and that makes around 5 or 6 in the 4k miles since I've had the car.

Gearbox position sensor....without doubt...it will just gradually get worse. Just don try and adapt your gearbox,as undoubtebly it will fail...

[shane@mbtech]

Linkage on top of box. Pin seizes.

[Mark CSL]

Just to add my csl was jumping out of gear into neutral it was the SMG Pump that failed new pump fitted and all is good