bypass transmission fault

[bbig119]

I've got a '94 540 which has had a manual 6 speed put into it, rather cleanly too. However, the LCD in the instrument cluster throws a trans fault all the time, which is kinda annoying.

I would like to try and bypass the fault and stop the car from throwing the fault altogether. I've looked in Bentley at electrical diagrams for the inst. cluster and the TCU, but its very vague about what each wire does. I'm not sure if the PO swapped the TCU when he did the swap, but he does have some wires coming from the TCU marked on the page for the instrument cluster in the Bentley that came with the car.

Two most important questions are: Is there a pin or two that I can jumper or ground out that will cause the TCU to stop communicating trans fault errors to the instrument cluster? Second, how difficult will it be to do this? As far as I know the TCU is behind the kick panel of the passenger side door. I just had the cluster out and know what it take to get at that.

[gale]

On an m30 535i/735i, shorting pin #5 to ground in the CCM (Check control module) gets rid of the trans program message. If I recall correctly, it is a grey-brown wire. See if you can trace schematics for the color/function of that wire from the CCM back tp the TCU, since it's easier to ground it at the TCU connector than at the CCM. For an m30, it's TCU pin #33 but it's certain to be a different pin for the m60. The pin assignments are numbered on the TCU and it's easy to correlate which connector socket to ground. Remove the TCU completely and sell it on ebay, it serves no purpose now that you have the manual trans.

[bbig119]

Thanks Gale,

I found a number of your posts on roadfly. Other than the Bentley, its about all I have as a reference.

Are there any consequences of shorting out the wrong pin here? Do I need to be sure of the pin ahead of time or can I try a couple to see what works?
I'm not even sure if the TCU is there or not, I haven't checked. Ideally I want to get in touch with the ower who did the swap to ask him about some of these things, but haven't yet gotten his contact info (2 owners ago).

Bryan

[Kalevera]

Get the pin at X511, the splice connector by the shifter, it's still Grey/Brown there, pin number 11. It doesn't follow factory convention -- the male side is the one to ground out.

The last time we did one of these (a few weeks ago), we burned a new inst cluster chip for the car. I'll still wager it can be done either way, but you'll be the one to confirm it.

Who did the swap?

best, whit

[bbig119]

Whit, I don't know yet. From what I've been told and read in the receipts, it is a guy in south east PA who did the swap himself. I'm hoping to get his contact info from the PO who sold me the car-- who bought it from the guy who did the swap so I can talk to him about this issue and probably several others.

I'll need to spend some time looking at the Bentley tonight to try and make sense of what you suggested. But am I to take "burned" as in fried the instrument cluster?

Thanks,

Bryan

[bbig119]

I found some posts by the PO who did the swap on roadfly. He apparently did look at the TCU at some point and spoke to someone at koalamotorsports who told him to send in the computer and they'll reprogram it to remove the trans fault message.

I'll likely contact koalamotorsports to get some details, and ask about sending it back, but I'm still interested in alternatives because sending it back will surely render the car useless for the period of time the computer is away and it may cost quite a bit of money to get reprogrammed. If there's another alternative I'm willing to look into it.

Bryan

[Kalevera]

Hah, I'm a tech at KMS.

Brett was talking about programming an instrument cluster chip for the car -- we did it for John's 540 a few weeks ago. You should still try the electrics bypass detailed in my earlier message, though. Didn't have enough time to work the magic on John's car, but I'm almost certain it can be done as I described (even if the car has ASC).

If it ends up needing a coding chip, it's a sub-$200 affair.

best, whit

[Scott C]

I found some posts by the PO who did the swap on roadfly. He apparently did look at the TCU at some point and spoke to someone at koalamotorsports who told him to send in the computer and they'll reprogram it to remove the trans fault message.

I'll likely contact koalamotorsports to get some details, and ask about sending it back, but I'm still interested in alternatives because sending it back will surely render the car useless for the period of time the computer is away and it may cost quite a bit of money to get reprogrammed. If there's another alternative I'm willing to look into it.

Bryan

Gale's post explains what I did to stop the fault from showing up....
In my case I needed the TCU so cut the wire between the TCU and CCM and grounded the CCM INPUT.

[bbig119]

Whit,

Sorry for being a little slow here, but I'm diving into new waters here. What you suggest I do is straightforward, but I'm having trouble finding any meaningful reference to the X511 splice connector either in Bentley or online. Could you provide me with a little more information on where this is exactly? Also the one reference or two that I did manage to pull up suggested that this only has 8 pins(I understand that you say it may be different than factory convention), so any insight here would be extraordinarily useful to me.

Thanks,

Bryan

Get the pin at X511, the splice connector by the shifter, it's still Grey/Brown there, pin number 11. It doesn't follow factory convention -- the male side is the one to ground out.

The last time we did one of these (a few weeks ago), we burned a new inst cluster chip for the car. I'll still wager it can be done either way, but you'll be the one to confirm it.

Who did the swap?

best, whit

[bbig119]

Get the pin at X511, the splice connector by the shifter, it's still Grey/Brown there, pin number 11. It doesn't follow factory convention -- the male side is the one to ground out.

The last time we did one of these (a few weeks ago), we burned a new inst cluster chip for the car. I'll still wager it can be done either way, but you'll be the one to confirm it.

Who did the swap?

best, whit

Whit,

Your suggestion appears to have worked. I haven't driven the car around much yet, but on the electronic end, it stopped throwing the fault. I'll have to trigger the ASC when I give it a test ride later today. Thanks for the help!!

Bryan