Need help simulating TCU inputs to my ECU

Venom · Post by **Venom** » Fri Oct 03, 2014 3:34 pm

Need help

Soooooo my car is converted to an early H6 running the factory H6 ECU, which was available as automatic only. My car is manual and I suspect the lack of TCU(or TCM) input causes some funny business.

Quick dirty work around is to ground the neutral wire from the ECU, putting the ECU in neutral mode all the time. This is how my car is wired up. Leaving it open and in drive constantly is worse. This also gives me a constant p1590 code (neutral switch voltage). No CEL but i'd rather it wasn't there, I'm reading it on my scangauge as a pending code.

B134-8 pin at the ECU is my neutral wire. When the clutch is pushed in or the gearbox is in neutral I want the ECU to be in "neutral" mode. The rest of the time it should be open and the ECU "in gear" mode.

Here's a document someone put together on RS25 for a solution.
http://www.rs25.com/forums/redirect-to/ ... 0p1507.pdf

Based on the information from this thread on RS25:
http://www.rs25.com/forums/f145/155496- ... ap-12.html

These people are making circuit boards with resistors to simulate transmission temp sensor output and correct voltages for the neutral switch inputs etc. None of this make any sense to me I am totally illiterate with electronics, and I've been looking at that RS25 thread and its fix for years now.

Anyone able to help me come up with a solution to this that doesn't involve a TCU/TCM??? Next step for me is an aftermarket ECU which I don't really want to do if I can avoid it.

Venom · Post by **Venom** » Fri Oct 03, 2014 3:41 pm

Some more info from around the interwebz.

Taken from this thread:http://sl-i.net/FORUM/viewtopic.php?f=31&t=12871
Hey guys, i know its been a while but ive learned a lot and want to update this thread with some more information for anyone else who might look at converting a 6cylinder early EZ30 to manual. Be it in an Outback or a GT30 or even when swapping the motor into another car - a lot of this information will be useful for you so pay attention!

Issues you will have and how i fixed them:

1) BHE and BEE chassis has a different brake pedal mounting to any other Subaru. The standard manual trans Subaru pedal will fit if you use a couple of crush tubes and longer bolts for the top mounts. When you get it in there youll see what i mean.

2) Weird gearshift response is caused by the ignition timing control in the stock ECU. The ECU expects to receive a load and shift timing signal from the trans control unit. Therefore - when you make a shift using a manual trans, the ECU is 'caught off gaurd' and you get a little bit of hesitation. This is impossible to avoid so just put up with it.

3) Check Engine Light. This is also unavoidable. You will get a code for 'TCU communication error'. This is because the ECU expects to receive constant data from the trans TCU and if it doesnt get data it likes (because you have a manual trans in there) you will get a code.

4) Rich spike at 3700rpm. This is the exact point when the variable geometry intake manifold switches from low rpm mode to high rpm mode. During this switch, the volumetric efficiency of the engine changes fairly quickly so the factory have programmed a rich spike in to avoid any detonation during this changeover. There is no way to remove this when running the factory ECU.

If anyone has any questions about the EZ30 motors, please feel free to flick me a message, Im happy to help. Now i'll go update my garage thread - have a read, its enlightening.

Gannon · Post by **Gannon** » Fri Oct 03, 2014 7:29 pm

If you dont use a TCU, you will always have a check engine light because the ECU and TCU have a communication bus between them and cannot be imitated. This is the reason for keeping the TCU and the resistors on the circuit board are for fooling the TCU so it can communicate with the ECU and keep the ECU happy.

Does your transmission have a neutral switch?

If not, maybe we could design a simple timer and latched relay combination hooked to the clutch or neutral switch that would latch on, fooling the ecu?

AndrewT · Post by **AndrewT** » Fri Oct 03, 2014 9:56 pm

Maybe Al has a solution? He's done a number of H6 conversions (including yours I gather?). Maybe he's got a solution now.

Venom · Post by **Venom** » Sat Oct 04, 2014 11:47 am

Haven't asked but I've looked at all of his H6 conversions (Kombi included) and he does the same he did to my car.

My transmission has a neutral switch. There are two switches on the side of the gearbox and both are plugged into the loom, what they feed into I don't know. Oh 1 must be reverse, of course. Hydrowill on ORS is parting out his Gen3 H6 so I'll see if i can get the TCU, plugs and a bit of the loom and that way I have something more substantial to work with.

Thanks for the replies

RSR 555 · Post by **RSR 555** » Wed Apr 29, 2015 11:26 pm

Can you use/try an ECU from an manual H6?

Venom · Post by **Venom** » Thu Apr 30, 2015 7:42 am

Yes well if i had the later H6 that might work. Mineis the earlier one that only came with an auto. I'll be revisiting this issue once the drivetrain is sorted. Later motors with manual are CANBUS anyway.

Donkeytits1 · Post by **Donkeytits1** » Tue Jun 21, 2016 12:36 am

Hey man sorry to revive an old thread, but did you sort out your ECU and shitty TCM troubles?

I'm about to embark on an EZ30D swap, trying to work out what to do with mine

Gannon · Post by **Gannon** » Wed Jun 22, 2016 7:40 pm

Matt Mcleod (kido tuning) can tune the EZ30D ecu to disable the tcu inputs.
PM me and I'll give you his number