To reduce the requirement to buy an entirely new accumulator suppliers in the aftermarket have decided to "rebuild" the original accumulator. To "rebuild" the accumulator the supplier welds a new valve to the back of the accumulator and introduces nitrogen through the gas valve into the gas chamber. This strategy is well intentioned, but it does not address the principle wear conditions as mentioned above.
To put it in the simplest of terms not all refurbished/rebuildable piston accumulators are manufactured the same. At MLR we have designed an accumulator that is fully rebuildable from the ground up. Our accumulator has:
Look for our accumulators with the upgraded designation and we can assure you that you will be getting a new accumulator in your vehicle.
]]>The PDK transmission relies on distance and speed sensors to record signals for speed and distance. The distance sensor unit, also known as the "sensor tower," records the position of each individual shift rod with the help of four integrated absolute distance sensors. If a distance or displacement sensor fails, the gearbox control unit is unable to communicate with the sensor pack, leading to gear shift failures and rendering the car undrivable.
The fault is typically indicated by codes such as P1731, P1732, P1733, P1734, P1735, and sometimes other 17xx errors.
Because dealership does not sell sensor separately the repair suggestion is to, replace the entire PDK transmission. The sensor is now available separately making it a much more cost-effective alternative. See here for our latest product offering.
This repair will fix the following warnings and codes:
It's important to note that there is no warning or way to prevent the distance/displacement sensor from failing. It's only a matter of time before the original sensor will go bad, so it's best to get it fixed as soon as possible.
]]>What is the BMW SMG Transmission's mechanism?
For those unfamiliar with BMW's SMG transmission, the best way to explain it is that it is neither a traditional "manual" nor a "automatic" transmission, but rather a hybrid of the two. There is no clutch pedal, but you can change gear using a "stick" (or paddles positioned right behind the steering wheel) much like you would in a regular standard. Instead, a computer controls the clutch, which is then operated by hydraulics.
Symptoms and Diagnosis: How to tell if an SMG pump has failed and requires replacement.
We connected the M3 to our computer diagnostics scan tool and discovered a DTC, or "diagnostic trouble code," indicating a problem with the hydraulic pressure, which is related to failing integral components on the SMG hydraulic pump assembly.
The SMG pump looks and works like an ABS pump, except it controls hydraulic pressures in the transmission rather than the brake system. We discovered that the huge, 40 amp fuse for the SMG pump (shown below) had blown with that information to send us in the right path. This is a very common and strong indication that the pump assembly has failed. We replaced the fuse and started the car to verify our theory, and the new fuse blew practically instantly.
What causes the car to not start when the SMG pump fails?
When the pump fails and the aforementioned fuse blows, the on-board computers that monitor and regulate the pump lose control with it and cannot control gear shifts. The clutch is engaged and unusable by the automobile's computers even if the car is in neutral. It's the same reason why you can't start a modern manual gearbox automobile unless the on-board computer receives a signal from the clutch switch indicating that the pedal has been pressed all the way in, disengaging the clutch before turning the engine over. Similarly, you can't start because of the same principle.
BMW SMG Pump Assembly Replacement
We replaced the SMG pump with our unit after determining that it was bad, cleared the codes from the on-board computer, and performed some QA/QC with a test drive to ensure that the problem was fixed and the vehicle was operating properly.
Related Product:
55 (0x37) Switching-on frequency of hydraulic unit
The smg pump is typically turned on to build/prime system to a certain pressure window. You will notice this most often when vehicle is has been parked for a while and you open door for first time, at that moment you will typically hear the smg pump turn on and prime system. Most of this fluid pressure is stored for later use in accumulator. The accumulator will supply fluid when needed for multiple shifting and clutch operations before electric motor/pump needs to be re-activated. This error code will present itself when DME calculates that it is having to turn on smg pump to frequently over a short period of time just to meet minimum pressure requirements.
There are a number of factors that can lead to this, most common problem in order of failure.
1-Electric motor is failing, during this time motor will provide low torque and not perform fast enough to build pressure in allotted time. It will eventually lead to complete motor failure.
2-High power relay(salmon relay) is damaged. This normally is related to item (1) where the additional load is causing high current to wear out relay.
Over time the relay will become unreliable and not follow DME instructions by either staying in an ON or OFF position. this could trigger two specific codes based on bellow.
3-SMG fluid level is low causing air to get to pump and not allowing any pressure build. If you have this problem recommend you bleed system to remove residual air in hydraulic system.
4-External Leak in hydraulic system causing loss of fluid leading to low pressure. Check for leaks. common area of smg slave cylinder or actuator leak will allow fluid level to get lower than minimum. When this happens the smg pump will starve not be able to build pressure.
5-Defective pressure sensor will cause an incorrect system pressure reading to DME and cause pump to be turned on more than needed. The actual system pressure will be higher than stated to DME but pump will be triggered to stay on longer as the feedback reading to DME will state low. (This could trigger a number of other codes 53(0x37), 53 (0x38) and 53 (0x39))
6-Pressure accumulator not within speciation. When accumulator is not in spec. it will not store enough reserve pressure causing pump to activate more frequently to allow you to initiate a clutch/shift request.(Run specific test for accumulator to determine health)
7-Wiring harness damage or fuse damage, this could occur if relay is stuck ON overheating wire harness and damaging insulation.
8-Internal leak in hydraulic system, worn out parts in smg system will allow pressurized fluid to escape back into reservoir. some areas are
]]>
56 (0x38) Switching-on time of hydraulic unit
The smg pump is typically turned on to build/prime system to a certain pressure window. You will notice this most often when vehicle is has been parked for a while and you open door for first time, at that moment you will typically hear the smg pump turn on and prime system. Most of this fluid pressure is stored for later use in accumulator. The accumulator will supply fluid when needed for multiple shifting and clutch operations before electric motor/pump needs to be re-activated. This error code will present itself when DME calculates that it is taking too long to build pressure to minimum requirements.
There are a number of factors that can lead to this, most common problem in order of failure.
1-Electric motor is failing, during this time motor will provide low torque and not perform fast enough to build pressure in allotted time. It will eventually lead to complete motor failure.
2-High power relay(salmon relay) is damaged. This normally is related to item (1) where the additional load is causing high current to wear out relay.
Over time the relay will become unreliable and not follow DME instructions by either staying in an ON or OFF position. this could trigger two specific codes based on bellow.
3-SMG fluid level is low causing air to get to pump and not allowing any pressure build. If you have this problem recommend you bleed system to remove residual air in hydraulic system.
4-External Leak in hydraulic system causing loss of fluid leading to low pressure. Check for leaks. common area of smg slave cylinder or actuator leak will allow fluid level to get lower than minimum. When this happens the smg pump will starve not be able to build pressure.
5-Defective pressure sensor will cause an incorrect system pressure reading to DME and cause pump to be turned on more than needed. The actual system pressure will be higher than stated to DME but pump will be triggered to stay on longer as the feedback reading to DME will state low. (This could trigger a number of other codes 53(0x37), 53 (0x38) and 53 (0x39))
6-Pressure accumulator not within speciation. When accumulator is not in spec. it will not store enough reserve pressure causing pump to activate more frequently to allow you to initiate a clutch/shift request.(Run specific test for accumulator to determine health)
7-Wiring harness damage or fuse damage, this could occur if relay is stuck ON overheating wire harness and damaging insulation.
8-Internal leak in hydraulic system, worn out parts in smg system will allow pressurized fluid to escape back into reservoir. some areas are
57 (0x39) Switching-on time of hydraulic unit
The smg pump is typically turned on to build/prime system to a certain pressure window. You will notice this most often when vehicle is has been parked for a while and you open door for first time, at that moment you will typically hear the smg pump turn on and prime system. Most of this fluid pressure is stored for later use in accumulator. The accumulator will supply fluid when needed for multiple shifting and clutch operations before electric motor/pump needs to be re-activated. This error code will present itself when DME may see different scenarios from pressure rising or dropping when it does not expect to see this happen over time. it could be a derivative of multiple error codes over time that will trip this particular code to be turned on.
There are a number of factors that can lead to this, most common problem in order of failure.
1-Electric motor is failing, during this time motor will provide low torque and not perform fast enough to build pressure in allotted time. It will eventually lead to complete motor failure.
2-High power relay(salmon relay) is damaged. This normally is related to item (1) where the additional load is causing high current to wear out relay.
Over time the relay will become unreliable and not follow DME instructions by either staying in an ON or OFF position. this could trigger two specific codes based on bellow.
3-SMG fluid level is low causing air to get to pump and not allowing any pressure build. If you have this problem recommend you bleed system to remove residual air in hydraulic system.
4-External Leak in hydraulic system causing loss of fluid leading to low pressure. Check for leaks. common area of smg slave cylinder or actuator leak will allow fluid level to get lower than minimum. When this happens the smg pump will starve not be able to build pressure.
5-Defective pressure sensor will cause an incorrect system pressure reading to DME and cause pump to be turned on more than needed. The actual system pressure will be higher than stated to DME but pump will be triggered to stay on longer as the feedback reading to DME will state low. (This could trigger a number of other codes 53(0x37), 53 (0x38) and 53 (0x39))
6-Pressure accumulator not within speciation. When accumulator is not in spec. it will not store enough reserve pressure causing pump to activate more frequently to allow you to initiate a clutch/shift request.(Run specific test for accumulator to determine health)
7-Wiring harness damage or fuse damage, this could occur if relay is stuck ON overheating wire harness and damaging insulation.
8-Internal leak in hydraulic system, worn out parts in smg system will allow pressurized fluid to escape back into reservoir. some areas are
54 (0x36) Exceeding pressure range
This error code will present itself when pressure sensor signal states system pressure is too high and cannot be controlled back within specification even when pump is de-energized.
There are a number of factors that can lead to this, most common problem in order of failure.
1-High power relay(salmon relay) is damaged.
Over time the relay will become unreliable and not follow DME instructions by either staying in an ON or OFF position. this could trigger two specific codes based on bellow.
2-Defective pressure sensor will cause an incorrect system pressure reading to DME.
3-Wiring harness damage, This could occur if relay is stuck ON overheating wire harness and damaging insulation causing pump to keep running contionously.
]]>Steps:
1-Remove smg clutch slave cylinder from bell housing(do not remove or loosen fluid line, keep fluid line connected to slave cylinder at all times)
2-Compress slave cylinder push rod into clutch slave cylinder and hold it in position.(Special tool available bmw 21 5 030)
3-Fill main reservoir with Hydraulic fluid, Loosen bleeder screw on secondary reservoir and wait until fluid starts to escape from bleeder screw. Close bleeder screw and fill main reservoir.
4-Mount special tool to pressurize reservoir and pressurize to 2.5bar/36psi.(BMW or aftermarket tool will work but should be used only for SMG)
BMW tool #
Warning! Any tools(Cap adaptor/hoses) used for this bleeding procedure that contacts hydraulic fluid should not be used for other systems like brakes etc. The fluid used in SMG system will damage any seal that is not designed to work with hydraulic fluid and lead to system damage or complete failure.
5-Connect(tool 21 5 020) bleeder hose and container to clutch slave bleeder screw. hold clutch slave in position where bleed screw is highest point and open bleeder screw.
6-When bubble-free hydraulic fluid emerges, Start allowing push rod to extend slightly and return back to compressed position.
Warning! Do not allow slave cylinder push rod to be release from compression at any time. doing so will allow push rod to be ejected forcibly from clutch slave cylinder.
7-If no air bubbles escape, close bleeder glove.
Note: At this point Main reservoir might have to be topped up with fluid and re-pressurized to 2.5bar/36psi.
8-De-presurize and remove special tools from main reservoir.
9-Slowly allow slave cylinder push rod to extend and remove special tool.
10-Re-install slave cylinder back onto bell housing.
11-Check main reservoir fluid level is full.
12-Perform bleeding procedure with diagnostic tool.
Note: Monitor main reservoir for fluid top up as residual air will be pumped into reservoir during diagnostic bleeding.
]]>
53 (0x35) Low level of pressure reached
This error code will present itself when pressure sensor signal states system pressure is too low and does not come back within specification even when pump is energized to priming mode.
There are a number of factors that can lead to this, most common problem in order of failure.
1-Electric motor is failing, during this time motor will provide low torque and not perform fast enough to build pressure in allotted time. It will eventually lead to complete motor failure.
2-High power relay(salmon relay) is damaged. This normally is related to item (1) where the additional load is causing high current to wear out relay.
Over time the relay will become unreliable and not follow DME instructions by either staying in an ON or OFF position. this could trigger two specific codes based on bellow.
3-Leak in hydraulic system causing loss of fluid leading to low pressure. Check for leaks. common area of smg slave cylinder or actuator leak will allow fluid level to get lower than minimum. When this happens the smg pump will starve not be able to build pressure.
4-Defective pressure sensor will cause an incorrect system pressure reading to DME and cause pump to be turned on more than needed. The actual system pressure will be higher than stated to DME but pump will be triggered to stay on longer as the feedback reading to DME will state low. (This could trigger a number of other codes 53(0x37), 53 (0x38) and 53 (0x39))
5-Wiring harness damage or fuse damage, this could occur if relay is stuck ON overheating wire harness and damaging insulation.
6-Blown Fuse power fuse will not allow power to electric motor. If fuse blown it could be related to underlying(item 1 or 2) system problem.
]]>
# |
Part |
Nm |
lb-ft |
lb-in |
11 |
Accumulator |
40 |
30 |
- |
12 |
Solenoid bolt |
4.4 |
- |
38 |
13 |
Pressure sensor |
15 |
11 |
- |
14 |
Temp sensor |
15 |
11 |
- |
15 |
Tank |
13 |
9 |
- |
16 |
Gear pump bolt |
6-7 |
- |
55-65 |
17 |
Retaining bolts |
8 |
- |
71 |
2 |
Wire harness bolt |
4 |
- |
35 |
SMG relay repair kit Part: 12 63 7 545 666
BMW Defect code 23 00 90 11 00
Affected Vehicle:
1999-2006 |
BMW |
325Ci |
E46; With SMG TRANSMISSION GS6S37BZ |
1999-2006 |
BMW |
325i |
E46; With SMG TRANSMISSION GS6S37BZ |
1999-2006 |
BMW |
330Ci |
E46; With SMG TRANSMISSION GS6S37BZ |
1999-2006 |
BMW |
330i |
E46; With SMG TRANSMISSION GS6S37BZ |
Vehicle symptoms:
-Engine cuts out when braking. No Fault code stored
-During coasting, an electronic engine management LED lights up sporadically. The check engine LED is lighting up briefly and the SMG transmission is switching automatically from automatic (cruise/drive mode) to manual mode. If sport mode has been selected, it is deactivated (sport LED goes off). Depending on the car’s road speed, if the transmission is in manual mode, it may also upshift automatically. No fault code stored
-Engine cannot be started, start inhibitor is active. Locking and then unlocking vehicle enables the engine to be started. “EWS tampering” fault codes stored in DME.
Other checks:
Signal “trigger” to relay from DME can be confirmed at DME pin # 30
Confirm relay is correct, this model relay is BMW part # 61366901469 it is not salmon relay type like other models.
Relay pins can be bypassed with +12v to confirm SMG pump is in working order, this will eliminate defective smg pump causing problem.
Following fault codes might be triggered for this issue 4F72 and 4FB4.
]]>This causes pre-charge gasses to escape into fluid section and eventually fail to provide enough accumulator back-pressure for system to function properly.
The common causes of accumulator failure are as follows:
In general, bladder accumulators tend to have a higher failure rate than piston types. In a lot of cases this is due to bladder diaphragm flexing. Over time molecular structure of material changes and creates a weak-point.
Typical symptoms of accumulator failure are:
Failure to diagnose and remove a bad accumulator will lead to abuse of pump section and premature failure of pump section components.
The accumulator should have enough capacity to provide multiple system activation's before it needs to be re-primed. This allows pump section and motor to have a good resting period before it is called upon to re-pressurize system.
Testing of accumulator should be done by specific test procedure to determine accumulator backpressure.
]]>
Some important things to note on both CSL and regular models this reservoir is technically an expansion tank, it should never be filled to the top especially when SMG system is pressurized. If you overfill system pressure in SMG system will slowly bleed off over time and the fluid from system will flow back into reservoir during this time. If it is over-filled to top the reservoir will overflow and leak fluid through breather port in cap. This fluid will then drip down into engine bay. If not identified correctly the leak might look like its coming from pump section and be misdiagnosed as a pump leak of some sort.
It is also important to note on non CSL version that there is a check valve at bottom of reservoir tank. This check valve slows/stops the flow of fluid when pump feed pipe is disconnected. To allow full flow, insertion of feed pipe needs to be in proper position and pushed all way through to release check valve and allow full fluid flow. Not doing this will cause SMG pump fluid starvation and introduce air into system this problem could come into play after system has passed bleed procedure and continues to introduce air in system periodically after vehicle has left repair shop.
With CSL type reservoir there is no check valve but due to the long hose section it is prone to having air pockets, we suggest dismounting reservoir and try keep feed line as straight as possible to allow air pockets release. if you still have problem then try remove line from pump until fluid flows and reinstall.
Once copper core is exposed it is just a matter of time before the different pinouts come in contact with each other. This causes erratic feedback values to go back to SMG DME confusing the processer and triggering numerous codes or erroneous drivability issues. There is no set code for this problem because it is a feedback sensor and the various shorts will lead DME to assume that another part in system is causing transmission to not respond.
It is recommended to either change whole harness or re-sleeve original wires with new insulation.
MLRENG: Repair harness PN: 30.110
]]>We have had some customers who changed out their fluid with one that primes faster etc. but their vehicles exhibited various problems during low ambient temperatures and worked fine once warmed.
Here is the main reason, "Temperature range" pentosin CHF11s fluid claims full performance from -40 to +130. that is a bold statement and is mostly to cater for automotive usage. Depending on where you are located, your ambient temperature for life of vehicle can be much different than another driver.
Most other fluids have a much smaller temperature range, similar to how you choose engine oil or octane level of pump gas you use every season. if you are constantly aware of your ambient/driving temps and drive your car based on this. you could use some of the other fluid's by choosing best range for your vehicle.
There is one aviation hydro fluid AEROSHELL FLUID 61 that provides an even greater range going from -40 to +204C and performance vs pentosin, but you have to buy a 55gallon barrel of it.
As we started off, CHF11s is a really good product that is widely available online and on many store shelf's across the country. Don't waste your time looking for a cheaper replacement, it doesn't exist.
]]>What it boils down to is the additional heat is being generated by the electric motor overworking itself and not internal engine temps. there are a few scenarios in which you might reach this threshold
1- Increased loading of smg system, at racetrack etc. in which you are asking the smg system to shift gears back and fort in rapid succession for long periods. this increases the on time of motor and heat associated with it not being able to cool down.
2-Electric motor bearings are dry causing additional strain on electric motor. The seizing bearings cause motor to use more power to overcome additional friction and increases on time of motor as it cannot run at high rpm due to increased resistance.
What the resistor mod does is reduce the true temperature reading from getting to the control module, the control module does not trip any lights because it has no idea of what i really going on.
yes this is a quick fix and it will most likely get you going for a few months but it is not a conclusive repair. the system does not like running that hot as fluid is not designed for that type of running temp, you will also have more leak-down of pressure and thus more on time of motor. this reduces life of motor even further.
Here is what we suggest
Type 1
Because you most likely are having this problem during track days. adding ducting to get more cool air to pump or physical relocation of pump to an area(trunk/drug bin) in which it has access to cooler ambient temps.
Type 2
You really need a new or rebuilt electric motor, if you are in early stages the resistor mod will give you about 6-12 months of driving after that you should start crossing your fingers. At minimum review the motor performance it is possible that bearings are seizing up.
]]>