Code 1738 plus Trans Fail Safe mode

Hello Bimmer peeps,

My 1997 740il is misbehaving....transmission has a few symptoms.

For the last year we have had issues with shifting if we left the shift mode switch in the default setting.....so we used the manual setting.....worked fine when shifted manually.

No leaks, no slippage, nothing serious except that our cruise control didn't work.

Until a few days ago when the trans went into Fail Safe mode......not sure if it's related but I pulled a code 1738 from the OBDII.....

I did some research......I am planning to service the trans fluid/filter, test the battery and alternator, and do the "unhook" the ABS harness test......


Anyone else have any other suggestions?


Question = Is it possible to reset the "trans fail safe mode" warning? or does the computer reset itself when the problem gets fixed? Unhooking the battery for a few minutes didn't work.....anyone have some info with this?


Thank you in advance!!

JH

I had some time yesterday to look at my car. A few days previous I did some more research on the issue and the code. The P1738 code is for the "pressure control solenoid C".

Just to weed out the other common problems that seem to happen to the 740's I tested my battery. Good shape. I tested my alternator. Good shape.

I'm ready to go deeper. Today I bought the trans fluid and trans filter.

Question= If my trans is low on fluid, wouldn't it make sense that the code for low pressure would show up?

I'm optimistic......I hope to see my problem solved once my trans fluid and filter are changed and the atf level is up where it should be.

Has anyone else had any experience with this situation?

I will post my results (hopefully with a bunch of happy )

JH

Unfortunately it is hard to get information on the transmissions. It is probably going to be an issue with the valve block or it's wireing. The good news is the valve block can be fairly easily rebuilt and is easy to remove. You are probably best to find a gearbox shop who.are prepaired to investigate and repair the problem without just throwing in another transmission. You could check the wireing and replace the solenoid when you change the fluid. Since the transmission is not slipping hopefully it is only the solinoid or the valve block. Now be glad you have an E38 not an E65. On the E65 the valve block contains the computer and is sealed and has to be replaced at huge expense ...

Thanks for the input. I hope to have the pan off today so I can get an idea of what the problem is. I will post the results.

JH

My tranny is only slipping in first gear only when I mash the gas. It only dose it in first. Or if I'm rolling and hit the gas I seems like the car dosent know what gear to go in so id dosent move rpms just go up.

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Battery? I've had these same issues before and after i replaced my battery I haven't had the trans fails safe MSG since.