Transmission Control Unit. Location ??? e34 1990

[Steve_M535iA]

Hi All,

I know these units are adaptive to driving styles and all that jazz, so the big question is on a 1990 E34 where the ***** is the damned thing! I have been up and down the paparwork and looked at all the modules I think would be the TCU but alas none have the right name nor the right number of pins on the connectors.

I just want to unplug it for a while and let it relearn whats going on after a few changes ....

Hoping someone here knows where it is! Oh BTW its an EU car - if that makes any diff.

Thanks

Steve

[Bill R.]

adaptive... It has adaptive hydraulic pressure control, which controls how soft or firm the shifts are. It does not have AGS which is adaptive transmission control. This is the program you're thinking of that changes the shift patterns based on driving style etc. You do not have this, and the only thing that happens when you disconnect the power to the tran control is you wipe out the settings on the adaptive hydraulic pressure control, your shifts will be harsh up and down until it readapts. That said since you probably won't believe me anyway, your transmission control unit is inside the kick panel on the passenger side infront of the front door. This is what it looks like after you remove it and take the cover off....
http://www.bimmernut.com/%7Ebillr/images/transcomp%20copy.jpg









Hi All,

I know these units are adaptive to driving styles and all that jazz, so the big question is on a 1990 E34 where the ***** is the damned thing! I have been up and down the paparwork and looked at all the modules I think would be the TCU but alas none have the right name nor the right number of pins on the connectors.

I just want to unplug it for a while and let it relearn whats going on after a few changes ....

Hoping someone here knows where it is! Oh BTW its an EU car - if that makes any diff.

Thanks

Steve

[RobPatt]

Nice picture. As I just installed Infinity Kappa components in the front (93 525ia) I also just found the location of the tranny control. Though I didn't touch it, I'm keeping that in mind if I "upgrade" to the Dinan A/T chip.

My question is, according to your photo, where is the chip? Will an A/T chip swap be as easy as the EAT chip was?

Thanks.
Rob sends....

[Bill R.]

the board, I've never changed one.. I would imagine that the dinan instructions would illustrate clearly which it is.. I had mine apart to fix a trans prog code.. which was the solder joints on the back of that relay that I have pictured.. Here's where the bad solder joints were.
http://www.bimmernut.com/%7Ebillr/images/transcomp1%20copy.jpg














Nice picture. As I just installed Infinity Kappa components in the front (93 525ia) I also just found the location of the tranny control. Though I didn't touch it, I'm keeping that in mind if I "upgrade" to the Dinan A/T chip.

My question is, according to your photo, where is the chip? Will an A/T chip swap be as easy as the EAT chip was?

Thanks.
Rob sends....

[Steve_M535iA]

Thanks Bill,

That answers one question but leaves another! The reason I am asking is that this:

My 535A has a strange driving issue when slowing down. Say you are doing 30mph light throttle and you take your foot off the pedal. The MPG guage slowly climbs to the right (0)mpg end and hovers about the 10-0 mark until you come to a stop. If you are doing say 50-60mph and do the same thing the guage swings to the (50)mpg end and past it (more or less fully left) and then once you get to 15mph you "feel" a gear change and the guage comes back from the left to about 30mpg and then with road speed drops to (0) (fully left) If you are in 'S' mode (sports in EU land and not snow) it can be made to do it on demand. The overrun feels like over run with the guage fully left and the car using some engine breaking once you hit the magic 15mph it feels like a gear or clutch engauges and the MPG guage behaves as if you were labouring a manual car.

Any of that make sence????!!!!!

Thanks

Steve

Oh I trust the unit is in the same (left hand side) on RHD and LHD cars?

[MarkD]

Nice picture. As I just installed Infinity Kappa components in the front (93 525ia) I also just found the location of the tranny control. Though I didn't touch it, I'm keeping that in mind if I "upgrade" to the Dinan A/T chip.

My question is, according to your photo, where is the chip? Will an A/T chip swap be as easy as the EAT chip was?

Thanks.
Rob sends....

The transmission EPROM is below that relay in the picture, and has a black plastic clip over it.

Mark

[Bill R.]

in the same location or not... if it is in your case it would be the drivers side kick panel... couldn't help you on the other issue though..






Thanks Bill,

That answers one question but leaves another! The reason I am asking is that this:

My 535A has a strange driving issue when slowing down. Say you are doing 30mph light throttle and you take your foot off the pedal. The MPG guage slowly climbs to the right (0)mpg end and hovers about the 10-0 mark until you come to a stop. If you are doing say 50-60mph and do the same thing the guage swings to the (50)mpg end and past it (more or less fully left) and then once you get to 15mph you "feel" a gear change and the guage comes back from the left to about 30mpg and then with road speed drops to (0) (fully left) If you are in 'S' mode (sports in EU land and not snow) it can be made to do it on demand. The overrun feels like over run with the guage fully left and the car using some engine breaking once you hit the magic 15mph it feels like a gear or clutch engauges and the MPG guage behaves as if you were labouring a manual car.

Any of that make sence????!!!!!

Thanks

Steve

Oh I trust the unit is in the same (left hand side) on RHD and LHD cars?

[Bill H.]

the transmission that may(?) be sending erratic signals about actual car speed.

[RobPatt.]

I'd guess it'd be the passenger side, but if not, either side is easy to access. Remove the pass. side kick panel (speaker comes with it), remove the speaker baffle (lifts right out) and you have a large ( approx 6 x 8 inches ) cavity. Immediatly up in this cavity is the module. It appeared to be removed by a few 7mm hex bolts, unplug the big cable, take out of the cavity, and do as you wish. Hope this helps, as I just did new speakers a few days ago and checked it all out.

Rob sends...
93 525ia 'EAT'd'

[Bill R.]

screws that hold the trans control all the way out, if you look at the holes in the body they are slotted with a keyhole, you loosen the screws then slide the whole assy up and the screws come out the keyhole cutout...That way when putting it back you don't have to try to hold it in place while starting the screws..





I'd guess it'd be the passenger side, but if not, either side is easy to access. Remove the pass. side kick panel (speaker comes with it), remove the speaker baffle (lifts right out) and you have a large ( approx 6 x 8 inches ) cavity. Immediatly up in this cavity is the module. It appeared to be removed by a few 7mm hex bolts, unplug the big cable, take out of the cavity, and do as you wish. Hope this helps, as I just did new speakers a few days ago and checked it all out.

Rob sends...
93 525ia 'EAT'd'

[Bellicose Right Winger]

Yes it does make sense. When coasting with engine speed over ~1700 RPM and throttle closed, DME shuts off all fuel to engine. Instantaneous MPG goes to infinity, full left on MPG gage, because you're accumulating miles but not using any fuel. When vehicle slows and engine speed falls below ~1700, DME turns fuel back on and MPG gage swings right to show fuel consumption rate.

In my 535ia I don't feel the effect you notice as you coast thru 15MPH w/closed throttle...although I'm sure my MPG gage behaves as yours does. Not sure if this is your trans downshifting, or some effect of turning fuel back on as I described above.

Paul Shovestul




Thanks Bill,

That answers one question but leaves another! The reason I am asking is that this:

My 535A has a strange driving issue when slowing down. Say you are doing 30mph light throttle and you take your foot off the pedal. The MPG guage slowly climbs to the right (0)mpg end and hovers about the 10-0 mark until you come to a stop. If you are doing say 50-60mph and do the same thing the guage swings to the (50)mpg end and past it (more or less fully left) and then once you get to 15mph you "feel" a gear change and the guage comes back from the left to about 30mpg and then with road speed drops to (0) (fully left) If you are in 'S' mode (sports in EU land and not snow) it can be made to do it on demand. The overrun feels like over run with the guage fully left and the car using some engine breaking once you hit the magic 15mph it feels like a gear or clutch engauges and the MPG guage behaves as if you were labouring a manual car.

Any of that make sence????!!!!!

Thanks

Steve

Oh I trust the unit is in the same (left hand side) on RHD and LHD cars?

[Steve_M535iA]

Sounds right, just did a quick drive and its at 1700rpm, so from what you've said that seems to be the reason. I guess it just one of those things you notice and assume the worsrt!

Thanks

Steve