Computer Problems with Manual Trans Swap

[mathamattox]

OK, so I have an H151 transmission that I want to swap into my 1996 LC. The mechanical aspects of this swap are relatively straight foward since most (if not all) of the parts needed can be sourced from a Toyota vehicle sold somewhere in the world.
My concerns are more with the electronic aspects of the swap. Right now my concern is about what the computer will do without an auto transmission. Some things I know (I think...):
- the speed sensor that feeds the speedometer and cruise control is in the transfer case, which I will retain so no worries there
- if I unplug the speed sensor on my current auto trans I do not immediately get a check engine light and the trans still seems to shift like normal, don't know what to make of that but it seems good since there is no secondary speed sensor on the manual trans
- unless I fool the vehicle into thinking that the vehicle is in park I will not be able to get my key out of the ignition because of the interlock with the auto trans shifter

Now, there are other harnesses that plug into the auto trans that I have yet to unplug to see the effect. The guys at my local dealer say that I will get a check engine light because the computer will think the shift solenoids in the trans are bad. Has anyone had a check engine light because of this?
I could probably build a circuit that will mimic the electrical characteristics of the shift solenoids to fool the computer, however I wonder if the computer will dislike sending the shift command to the trans and then not having the engine RPM change (since I may not shift the manual trans when the computer is telling the non-existant auto trans to shift). Another possibility is a computer from an overseas 1996 LC with a manual trans in a region where OBDII was standard in 1996. That to me seems like a long shot but it might work. Does anybody know for a fact whether any overseas LCs had OBDII in 1996?

OK, I know those are some loaded questions but they have been bugging me the last couple of days and I have to answer them sooner or later.

Thanks,

Jonathan

 

[PurpleFJ62]

intresting...

its about time people started to swap manual trannys into 80 series. when your done you will have the perfect vehicle.

I hope it works for you!

 

[Tapage]

Chec my Marilu thread .. I swap out my A442 for a nice H150 manual .. and if you can life with ocasional tranny OD flashing light .. it's cool ..

the only circuit that I need it's one for the reverse lights ..

 

[pr0ject42]

Subscribing to this guy. I've tried the auto thing here for a little while and I'm just not digging it.

It would be even sweeter to put a marks crawl box in at the same time you swap the H151 in.

 

[zx9r]

sorry can't offer any advice but anxious to see how this works out. This is my number 1 wish for my LC if time and money were no object...someday...good luck!

 

[mathamattox]

I have read through the Marilu thread a couple of times! It was very good reading. Do you have OBDII on your vehicles in Panama?

I'm starting to get the feeling that there are only and handfull of people interested in swapping manual transmissions into their 80s as I have started at least one other thread on the subject and the responses were relatively few.

I would enjoy putting in a crawl box, however after reading another member's thread on the install and breakage I do not trust them. I would much rather have a Klune-V in front of the T-case. Even the 3.1:1 gearset that Mark's sells would be OK. I do not plan on doing any extreme rock crawling so a ratio in the 50:1 range would be adequate, but 80:1 I think would be more ideal. Maybe Marlin Crawler will come out with something eventually.

In the mean time, anybody ever had their check engine light come on because of a bad shift solenoid??

 

[pr0ject42]

Do you know which connector(s) going to the ecu are responsible for controlling the tranny?

It may sound super crazy, but maybe grabbing another ECU from a 96, wiring it with power, then only hooking your tranny to that guy to control it, but leave your original in the truck to control everything else might be one way to test things without swapping trannys and getting past the point of no return.

Can anybody comment on that idea? This way you can see the ODBII codes that are getting kicked off by the ECU without the tranny hooked to it. Then maybe work out a phantom control box that could fool the ECU into thinking the auto tranny is there, or see if the JDM ECU from a 96 with a manual tranny would work and pass emissions requirements (ODBII compliant, emissions pass the sniffer test, etc).

Where did you get your H151 and parts? I really wanted to grab the set from lynchmob, but backed out because in CO I have got to pass emissions, meaning no CELs and there have been no firm answers on making it work and keeping the stock ECU happy. That would make that tranny a fairly big and expensive paper weight for me.

I spoke briefly with Slee about the idea, but he was rather negative-nancy about the idea. As best as I can tell, no one has done it on a ODBII vehicle, but I have heard of one guy who did it on a 94 since the ECU on those guys didn't control the tranny.

 

[TrickyT]

...It may sound super crazy, but maybe grabbing another ECU from a 96, wiring it with power, then only hooking your tranny to that guy to control it, but leave your original in the truck to control everything else might be one way to test things without swapping trannys and getting past the point of no return...

I don't think this will work. The ECU needs various sensor input in order to decide when to shift the A343F. Things like throttle position, speed and coolant temperature. The second ECU won't have that input and so won't know what to do. And I would definitely not try wiring the same sensor up to two ECUs.

 

[mathamattox]

I got the tranny from lynchmob about 3 months ago. I also have to pass the sniffer and no CEL tests at inspection here in NC but I believe there is a way to make it all work out.

Since I have not had any auto tranny trouble yet I do not actually know what happens when there is a problem with the tranny. I have heard that the OD light will blink? And if problems with the tranny do not cause a CEL then it won't matter what the computer thinks the tranny is doing because you won't fail inspection for a CEL and different transmissions do not effect emmissions output. So then you would be good to go on those issues.

I think that one ECU will be fine since, as TrickyT mentioned, the ECU needs input from a bunch of sensors to make its shifting decisions. The trick is to make sure the setup doesn't throw CELs. I'm hoping to do the swap just after passing inspection so I have the maximum amount of time to get things working properly before the next inspection.

 

[96r50]

I know there is at least one CEL that comes on for a transmission problem. P1780 is for the Park/Neutral Safety Switch Malfunction. Your FSM (which I would assume you have if you're contemplating a swap of this magnitude) should list all the codes for the automatic transmission.

 

[TrickyT]

A few more thoughts on this. First, on page AT-32 of the FSM it lists a bunch codes related to the transmission that will cause a MIL light. Theses are: P0500, P0710, P0750, P0753, P0755, P0758, P0770, P0773, P1700, P1780. Some of these are generated from the input of a bunch of sensors. For example, code P0770 - shift solenoid E malfunction. The FSM says "the ECU uses the signals from the throttle position sensor, the AFM, and the crankshaft position sensor to monitor the engagement condition of the lock-up clutch. ...it compares the condition of the lock-up clutch with the lock-up schedule in ECM memory to detect mechanical trouble of the shift solenoid valve..." and if a problem is detected a P0770 is thrown.

I think it's going to be pretty hard to avoid that code. Similarly, codes P0750 and P0755 are also problematic because they are generated when the ECU thinks the transmission should be doing one thing, like shifting, but the speed sensor or crankshaft sensor says the event didn't happen as it should.

The other codes are reasonable easy to avoid by using resistors to simulate the actual sensor. For example, an 8 K ohm resistor in place of the ATF fluid temp sensor will just make the ECU think the fluid temp is normal. But the 0750, 0755, and 0770 codes are going to cause you headaches that I can't think of how to get around.

Wish I had some ideas for ya.

 

[70sguy]

Have you tried getting a 5spd ECU out of AUS or Europe?
General Market EPC shows
89661-60340 for 95/01 up Computer, Engine Control FZJ80 LHD 5F EFI
Japan Market EPC shows
89661-60300 for 95/01 up Computer, Engine Control FZJ80 MTM (RHD)
More than likely the only difference between LHD and RHD ECU is mounting brackets.

You will need General Market EWD 232F if you want to cross reference the differences between ATM and MTM and understand how they relate to the Engine ECU.

May the force be with you.

 

[mathamattox]

Yes, some of those codes do sound difficult to avoid.

I mentioned in my first post that I would have to make the ECU think that the trans was in P in order to remove the key from the ignition after the engine was shut down. So if the ECU thinks that the trans is in P, I wonder if that would keep the codes from coming up?

I wish they had made a transmission MIL for transmission problems. Then I wouldn't have to worry about all this crap

I am still interested in swapping the ECU from an overseas model, but have NO DEFINATIVE ANSWER ABOUT OBDII!!!! And that is certainly the clincher for that solution.

So if you know anything about OBDII in overseas cruisers please share with us as this could certainly help!!

 

[lt1fire]

Yes, some of those codes do sound difficult to avoid.

I mentioned in my first post that I would have to make the ECU think that the trans was in P in order to remove the key from the ignition after the engine was shut down. So if the ECU thinks that the trans is in P, I wonder if that would keep the codes from coming up?

I wish they had made a transmission MIL for transmission problems. Then I wouldn't have to worry about all this crap

I am still interested in swapping the ECU from an overseas model, but have NO DEFINATIVE ANSWER ABOUT OBDII!!!! And that is certainly the clincher for that solution.

So if you know anything about OBDII in overseas cruisers please share with us as this could certainly help!!

I believe, but am not 100%, they are OBDII

 

[mathamattox]

I sent an enquiry to the service department of Toyota dealership in Sydney, AU regarding the OBDII question. I will post here when I hear back from them.

 

[Tapage]

I have read through the Marilu thread a couple of times! It was very good reading. Do you have OBDII on your vehicles in Panama?

yes .. but I got the impresion that are not the same OBDII as you get in USA .. at least in Marily wasen't a problem since hes have a Turbo Diesel heart ..

But in wife FZJ80 that comes factory manual and it's OBDII also .. don't have any tranny inputs on the ECU .. maybe coz diferent ECU ..

 

[TrickyT]

...
I mentioned in my first post that I would have to make the ECU think that the trans was in P in order to remove the key from the ignition after the engine was shut down. So if the ECU thinks that the trans is in P, I wonder if that would keep the codes from coming up?...

If the park signal says the tranny is in park but the speed sensor says the vehicle is moving it's hard to say what the ECU will do. Both sensors can't be right. If I was the ECU designer I'd throw a trouble code. Edit: Indeed, the FSM says P1780 occurs if the park switch is on and vehicle speed is 44mph or more. (And you obviously can't just disconnect the speed sensor from the ECU, 'cause then you'll throw a code for that.)

 

[cruiserdan]

intresting...

its about time people started to swap manual trannys into 80 series. when your done you will have the perfect vehicle.

I hope it works for you!

I guess you haven't wheeled an 80 hard then?

 

[cruiserdan]

Several years ago Alan Podvin put a manual trans in one and I believe he kept the stock ECU.

 

[mathamattox]

Several years ago Alan Podvin put a manual trans in one and I believe he kept the stock ECU.

Was his by chance a 96 or 97? If so we need to talk to this man!!

I want a manual for both the street and the trail. To me there is just nothing else that will do.

One situation where the wheels could turn with the trans in P is if you have the Tcase in neutral. This will give you a warning light on the dash. Wonder if you could make the ECU think that the trans was in P and the Tcase in neutral to get around the MIL? I'm just throwing out ideas here, not sure if they will actually work. But then, thats the purpose of this thread is to throw some ideas around and see what sounds feasible.