SMG Woes - Need Assistance

[Grayson]

I need your help...

Story time.

Past: Cog light has been on for 3 weeks at this point (please don't flame me, be gentle) but no shifting issues or any symptoms of a malfunctioning smg. I thought heat related and kept dailying the car. When arriving home from work, car off, I heard the smg reservoir priming over and over again. Opened the res tank and saw it was low, and the sound (I thought) was the pump trying to suck fluid while being dry so I topped it off, checked for leaks, saw none and replaced the salmon relay (read somewhere to do that). So the priming sound / issue went away for 2 weeks.

Present: Woke up to dead battery after a long weekend not driving the car. When I hooked up the cable to jump the first this I hear is the priming sound. So it killed the battery apparently. I unplug the salmon relay and plug it back it and the priming sound stops, get the car jumped and drives fine. Thinking the res maybe low again I open the tank and its BRIMMED to the top with fluid. All the way to the rim. Uh huh? There is also fluid all around the cap on the outside so I think it's been leaking from the cap since it now has too much fluid. I stopped driving the car daily and took the relay out the keep the battery from dying just in case it goes prime mode again. Even though it hasn't acted up since.

What is going on here? Could it be solved with a simple bleed of the system? I did replace my starter recently (within 6 months) so maybe during that install air go into the system (removal of the reservoir is required for starter install)? Are these symptoms associated with the smg pump leaking internally (good god please no)? Any help or insight into this is greatly appreciated. To scared to drive the car now for fear of causing more damage but not afraid to fix stuff if I know what it is I'm taking apart and why.

Thanks in advance.

TLDR: Cog light, Pump/reservoir priming continuously while car is off, salmon relay unplug & plug back in temporarily stops priming, smg hydraulic fluid levels in res low one day to high another day. (obligatory "time to manny swap" comment)

[oceansize]

The car should be cold when checking the SMG fluid. You weren't low so you overfilled. It sounds as if your accumulator has failed and/or the seals inside the pump have gone bad and it cannot build pressure. DIS or INPA (with the full suite of SMG utilities) can do accumulator tests. Hook up INPA and look at pump pressure and see what your pressure sensor is reading. Pressure sensor could also be bad. Can sometimes read -1 when it goes. You should build pressure up to 80 bar and then the motor will switch off. I'm sure you are never getting there.

[sapote]

When arriving home from work, car off, I heard the smg reservoir priming over and over again. Opened the res tank and saw it was low, and the sound (I thought) was the pump trying to suck fluid while being dry so I topped it off

Hopefully it was low fluid which led to air in the system and pump can't build up pressure. I would try to bleed the air out first (you found fluid overflow the reservoir the next day which means air in the system) and see if the pump no longer running continuously.

[Grayson]

The car should be cold when checking the SMG fluid. You weren't low so you overfilled.

Thank you. You are correct car was still warm when I topped off so I must've mistakenly over filled. Will suck out some fluid to proper level

DIS or INPA (with the full suite of SMG utilities) can do accumulator tests.

Not super familiar with either acronym you used here but am doing my best to learn through googling. I don't own a laptop so not sure how I'm going to get this test done. Perhaps a shop can help me see if I'm getting to pressure. IF it turns out my pressure is low, would this be indicative of a pump failure (replace) or is there other fix for low pressure situations? Because good god these smg pumps are crazy expensive online...

Hopefully it was low fluid which led to air in the system and pump can't build up pressure.

It seems like this cant hurt anything to try and bleed the system and I probably should've done thi sanyway when i reinstalled the resivior during the starter swap. Will give it a go.

[oceansize]

Motor, pump seals, solenoids, sensors, and accumulator can all be replaced independently. However most shops won’t touch internal pump seals with a ten foot pole.

DIS is an old BMW specific diagnostic tool. Runs on a VM on Windows. INPA is slightly newer and will run natively on Windows.

If you take it to the shop without SMG experience they will simply want to replace the entire pump. You need someone who knows the SMG system if going that route. You definitely need to run some diagnostics otherwise you and your shop will throw parts at the problem.

Make sure your battery is fully charged as the SMG system can behave erratically if the battery is low.

[eacmen]

If you're waking up to a dead battery are you hearing the pump prime over and over? Not sure why it would kill your battery unless there was an errant sensor (door, trunk, lock) triggering the pump to prime.

Personally I wish the smg pump wouldn't prone until ignition switch is turned. For some reason any occupancy sensor changing state triggers smg pump.

[sapote]

Personally I wish the smg pump wouldn't prone until ignition switch is turned. For some reason any occupancy sensor changing state triggers smg pump.

Agree. Wonder if the door/trunk sensors can be coded out from the SMG pump control?
BMW didn't care about the life of the pump; they just wanted the SMG pressure is ready to shift as soon as user got inside the car.

[karter16]

Agree. Wonder if the door/trunk sensors can be coded out from the SMG pump control?
BMW didn't care about the life of the pump; they just wanted the SMG pressure is ready to shift as soon as user got inside the car.

I imagine it's because they were concerned that people were going to jump in the car, switch the ignition on and then try to immediately shit into neutral so they could start the car. They probably didn't want people to then have to wait for the system to build pressure before they could select neutral and start.

(not saying the way it's done is ideal, but that's probably why they did it)

[sapote]

They should prime the pump to build up pressure before cranking the starter. What can go wrong with the logic?

[eacmen]

Not to get too off topic but I have often thought of adding a toggle switch for smg pump relay but it will end up triggering cog light.

I wonder if the sensor values are individual pins on the smg ecu. Might be able to just pull the pins and pull them to gnd/vcc?

[Grayson]

DIS is an old BMW specific diagnostic tool. Runs on a VM on Windows. INPA is slightly newer and will run natively on Windows.

If you take it to the shop without SMG experience they will simply want to replace the entire pump. You need someone who knows the SMG system if going that route. You definitely need to run some diagnostics otherwise you and your shop will throw parts at the problem.

Thanks for the information. Maybe I can "youtube warrior" my way through the test. Regarding the shop thing, that's what I'm most worried about. Feel stuck... I have an issue that needs addressing but no one with the appropriate knowledge to deal with the issue. I'll try to hit up some local Facebook groups and see what skilled labor I can muster up. Really appreciate your time.

If you're waking up to a dead battery are you hearing the pump prime over and over? Not sure why it would kill your battery unless there was an errant sensor (door, trunk, lock) triggering the pump to prime.

Perhaps prime is the wrong word choice. It's a whirring sound coming from the reservoir tank, not the pump itself. Like it's trying to suck fluid repeatedly. 2 seconds on, 2 seconds off in perpetuity until the battery dies. If I un plug the salmon relay and plug it back it the sound goes away and then primes as normal when i unlock the car etc. Weird.

[eacmen]

Have you read the codes from smg ecu?

[sapote]

“Perhaps prime is the wrong word choice. It's a whirring sound coming from the reservoir tank, not the pump itself.”

The only thing can cause the noise in the reservoir is the pump sucking air.
Bleed it.

[sapote]

“I wonder if the sensor values are individual pins on the smg ecu. Might be able to just pull the pins and pull them to gnd/vcc?”

Great idea. Switch the signal to 4v will fool the TCM as high oil pressure after turning engine off, and connect back to sensor when ready to drive. Only one wire is involved.

[oceansize]

Thanks for the information. Maybe I can "youtube warrior" my way through the test. Regarding the shop thing, that's what I'm most worried about. Feel stuck... I have an issue that needs addressing but no one with the appropriate knowledge to deal with the issue. I'll try to hit up some local Facebook groups and see what skilled labor I can muster up. Really appreciate your time.

You need this cable. You need this software (BMW and Mini Diagnostic Software) for $50. Has everything you need including the full suite of SMG utilities within INPA, two versions of DIS, Tool32, WinKFP, etc. Of course you also need a Windows laptop. You can also try Mike's BMW Tools which is free but I don't have a valid link and I don't know what it does or doesn't have.

Where do you live? It is possible someone might be able to recommend a shop.