speedo issues after 1uz conversion.

[Shane]

So my son has his 1uz conversion on the road and it looks and sounds great. Its an early 1uz from a ls400 and in a TT shell. We have a few loose ends to tie up now and the one that is giving me problems at the moment is the speedometer.

 

All the guides and common sense say the supra speedo signal up to the odo and speedo should come from the ECU speedo output"SP" on the 400 ecu. However there is nothing from this, I haven't scoped it yet but am confident there's not a lot coming from this pin. If I feed the speedo from SP+ from the gearbox sensor where it goes into the ecu then I get a speedo, but by the time we are doing about 40 the speedo is off the clock. Incidentally the sensor came with the transmission, engine and ecu all from the same donor car.

 

I tried taking the speed signal from the front ABS sensor instead and the results are virtually identical.

 

Any suggestions from those who have done this conversion previously?

[Mike2JZ]

Normally on the Supra you have the gearbox speed signal which goes directly to combination meter. From there, the signal gets distributed to ODO & ECU SP1

 

Speedo will work regardless of what ECU sees if you wire it up in a similar fashion.

[Shane]

Normally on the Supra you have the gearbox speed signal which goes directly to combination meter. From there, the signal gets distributed to ODO & ECU SP1

 

Speedo will work regardless of what ECU sees if you wire it up in a similar fashion.

Thanks Mike. Sensor output goes straight to the LS400 ecu in this case, part of the original 400 loom config. Connecting it as you describe gives the symptoms we have now, it works yes but is off the clock.

[Mike2JZ]

Thanks Mike. Sensor output goes straight to the LS400 ecu in this case, part of the original 400 loom config. Connecting it as you describe gives the symptoms we have now, it works yes but is off the clock.

 

What gearbox are you using?

[Shane]

From the ls, pretty much the same as the NA box. I know what you are probably thinking, that the sensor from the ls400 is putting out a higher pulse rate than a TT box, its possible. Somehow I had in my mind that the wheel sensors put out about the same as the gearbox sensor, maybe I dream't that but for sure when I use the wheel sensor instead its pretty much the same issue.

 

I guess I can hook a scope or frequency counter up to my TT and make a comparison but was hoping someone had been here before to save me bit of time.

[Mike2JZ]

1) I would pull the speed sensor and confirm that the cog has the same amount of teeth as that of the NA/TT Supra boxes. The frequency has to be the same between the two otherwise you will hit issues.

 

2) Pulling wheel speed off ABS sensor is also not going to work. ABS rings have a lot of teeth hence frequency is really high on them. You would require to run an intermediary box in order to interpret that signal and output a signal that the speedo can accept.

 

3) Check another combination meter, check your's isn't faulty.

[David P]

The no.2 speed sensor gear-pair are matched to the LS400 diff ratio.

 

If the problem was originating from here, the gear changes would be chaos too.

[Shane]

1) I would pull the speed sensor and confirm that the cog has the same amount of teeth as that of the NA/TT Supra boxes. The frequency has to be the same between the two otherwise you will hit issues.

 

2) Pulling wheel speed off ABS sensor is also not going to work. ABS rings have a lot of teeth hence frequency is really high on them. You would require to run an intermediary box in order to interpret that signal and output a signal that the speedo can accept.

 

3) Check another combination meter, check your's isn't faulty.

 

Thanks but its not the sort of error from a few teeth less or minus, its a huge error. If it comes to it I can use a pic processor and build a little interface to use the wheel sensor but seems pointless as it should be doable without.

 

I will stick my pod in it and see if its the same.

The no.2 speed sensor gear-pair are matched to the LS400 diff ratio.

 

If the problem was originating from here, the gear changes would be chaos too.

 

Thanks Dave, as you know it changes smoother than a gravy sandwich. But you have made me think..I am starting to question myself now and wonder if I have tapped into the wrong transmission sensor Will check it out next weekend.

[TRD-1]

I have a similar issue on the same conversion on a Mk1 GS300, but my speedo isn't out as much as yours. I looked on ToyoDiy and in my case the same year of cars use the same speed sensors on the gearbox, so Ive just re positioned the needle to show it a bit accurate as a temporary measure.

[David P]

I have a similar issue on the same conversion on a Mk1 GS300, but my speedo isn't out as much as yours. I looked on ToyoDiy and in my case the same year of cars use the same speed sensors on the gearbox, so Ive just re positioned the needle to show it a bit accurate as a temporary measure.

 

The speed sensor is the same one on all of the A34#E boxes, it is the gear-pairs that drive it that are different within the different variants of the boxes.

 

To correct your speedometer and more importantly, to have the gears changing at the correct engine rpm, fit a GS300 no.2 speed-sensor gear-pair into the tail-shaft housing on your A341E? box.

[Shane]

The speed sensor is the same one on all of the A34#E boxes, it is the gear-pairs that drive it that are different within the different variants of the boxes.

 

To correct your speedometer and more importantly, to have the gears changing at the correct engine rpm, fit a GS300 no.2 speed-sensor gear-pair into the tail-shaft housing on your A341E? box.

 

So reading up a bit more on this today, No.2 which on the LS ECU pinout is designated SP2- and SP2+ I think from memory is purely for the ecu to determine shifting? Sensor No.1 is primarily for the speedo? I understand a bit more about the configuration now and also the pin SP on the ecu that one of the guides tells you drives the speedo is incorrect and in fact this is the opposite and should have the buffered output (ye old "pink wire" on the JZA80) from the odo returned to it to prevent fault codes relating to duff sensors being created.

 

 

Found this which should be enough to get us up and running.

http://www.lextreme.com/forums/index.php?threads/1uz-speedo-setup-with-rf1a-t-case-help.16249/

 

Thanks for the feedback and info guys, will report back next week but looking at my wiring notes now I can see I have used the SP+ signal from sensor No.2 and left No.1 disconnected which is completely wrong. Such a shame we didnt have complete looms to work with, but nearly there now.

[TRD-1]

Looking into this further, mine is a 1UZFE from a UCF20, and after looking at the ECU pinouts, the LS has a No.2 speed sensor which outputs SP+ and SP2- which both go direct to the ECU, the only other speed sensor is the OD speed sensor which is labeled up as NCO+ and NCO- and also goes direct to the ECU....For the speedo signal the ECU has a output labeled SPDM which goes direct to the speedo. I don't think there is any interference with gear changes as the signals upto the ECU should be fine long as both sensors are connected up directly?

 

The setup is different on the GS and maybe the supra to where the speedo signal first goes to the speedo unit and from there to the ECU (in this case a wrong speedo signal would effect gear changes etc).

 

Regarding the Speedo needle unit itself that most probably is what is reconstructing the signal to display the LS400 speedo correctly. What I was gonna do is to remove the LS400 speedo needle unit out of the cluster and wire the rear circuit inline to the speedo in my GS and see if that corrects it.

 

Shane in terms of getting your speedo working, you will have I guess 2 wires that come from the speedo cluster and should be part of the interior loom these are the 2JZ speed sensor wires, you need to connect one of those to the SPDM signal out put on the 1UZ ECU this is how I got mine working, its still off but only slightly not as much as yours currently is. With mine connected this way the speedo needle is out by about 6-10mph across the speed range as is the Odometer reading.

Edited November 7, 2018 by TRD-1 (see edit history)

[Shane]

Looking into this further, mine is a 1UZFE from a UCF20, and after looking at the ECU pinouts, the LS has a No.2 speed sensor which outputs SP+ and SP2- which both go direct to the ECU, the only other speed sensor is the OD speed sensor which is labeled up as NCO+ and NCO- and also goes direct to the ECU....For the speedo signal the ECU has a output labeled SPDM which goes direct to the speedo. I don't think there is any interference with gear changes as the signals upto the ECU should be fine long as both sensors are connected up directly?

 

The setup is different on the GS and maybe the supra to where the speedo signal first goes to the speedo unit and from there to the ECU (in this case a wrong speedo signal would effect gear changes etc).

 

Regarding the Speedo needle unit itself that most probably is what is reconstructing the signal to display the LS400 speedo correctly. What I was gonna do is to remove the LS400 speedo needle unit out of the cluster and wire the rear circuit inline to the speedo in my GS and see if that corrects it.

 

Shane in terms of getting your speedo working, you will have I guess 2 wires that come from the speedo cluster and should be part of the interior loom these are the 2JZ speed sensor wires, you need to connect one of those to the SPDM signal out put on the 1UZ ECU this is how I got mine working, its still off but only slightly not as much as yours currently is. With mine connected this way the speedo needle is out by about 6-10mph across the speed range as is the Odometer reading.

Thanks for the reply. I will let you know for sure at the weekend so long as I am well enough to work on his car (been pretty ill recently). Can't say for your car, but my thoughts at this time knowning what I do now is this:

 

SPDM on ours has nothing useful on it, SP2- & + do and I am more than happy the box is changing correctly. Nigel Wade's excellent guide suggests what you are saying too that the speedo is driven by SPDM. I think its an error and as good as the guide is, on ours at least I have come up against a few discrepancies so far. The link I put in my last post for an early 400 shows Sensor 1 is present and drives the speedo, I will confirm this at the weekend, fingers crossed and all that.

 

I also think there is every chance the output from sensor 1 goes to the speedo and then onto the odo. In the JZA80 at least, its at this point where it is subjected to a little buffering and fed back to the ECU (search pink wire mod). If you look through the possible transmission fault codes for the LS400, one of them is generated when the ecu doesn't see action from sensor No.1. I think the buffered output from the ODO goes back to SPDM to allow the monitoring of Sensor 1 and for this code to be generated, how else could it do so? It could be and sounds like that on yours it's different

 

Thanks again and will conform after the weekend all being well. Certainly hope I am right and the speedo isnt driven by SPDM becasue if so I have a duff ECU and the options are limited then, find a still working early LS400 ECU, or live with this one and start counting pulses and build a little divider so we can use a wheel sensor.

[Wez]

Any reason you chose to use this gearbox over the stock Supra unit?

 

I have an LS430 which I plan to pull the motor from, although I am using it as my daily at the moment, such a nice drive

[Shane]

Any reason you chose to use this gearbox over the stock Supra unit?

 

I have an LS430 which I plan to pull the motor from, although I am using it as my daily at the moment, such a nice drive

 

Hi Wes, only becasue the engine and box came as a package. It made sense to stick with it as I have used the ecu from the same vehicle also. DavidP did his stuff on the box and OK'd it in terms of compatibility and its pretty much the same as a supra box I believe. Also, the Supra was a bare shell and was bought without box. I am now almost certain that the No1 sensor is present and that I haven't used it, as in its connected to nothing at present. I may find when I look on Saturday that I am wrong, but am pretty confident thats going to be the case. I don't do Facebook but my son does, think he has put all the buid on there if you want to take a look. Paul Hogarth.

[Shane]

An update:

 

Paul got under the car and hung an oscilator on the plug going to No1 sensor, quickly found the wires in the loom inside the car and as I suspected I had never connected No1 sensor up. Excellent we think, job done. Five minutes later Supra pod connected to No1 sensor and time to test, by the time he had travelled a few metres speedo reckoned we were doing about 50! Aha, so the speedo/pod is faulty. Dug out an old TT speedo I had and hooked it in down inthe passenger footwell to test, exactly the bloody same.

 

 

Done a bit more digging and discover the older LS400 No1 sensors put out 20 pulses per revolution of the transmission output shaft compared to 4 pulses to every rev from the No1 sensor of the Supra.

 

I need to decide do we find gears and sensor from a supra and then struggle to change them on this transmission, or do I build a divider circuit

dividing pulses by odd numbers isn't as simple as evens, but can be done and simply put this in line.

 

 

Also studied a LS diagram in conjunction with a LS ECU operation description and can confirm SPD pin on the ECU does not drive a speedo. This pin does get a buffered output of the same signal fed to it. The only reason I can think it should have this is to generate a gearbox code to let you know when Sensor1 has no output. Mention it only in case it helps someone else when searching.

[David P]

I know that you have forgotten more about electrickery than I have ever leaned, however, this problem must be somewhere in the OE loom that you don't have?

 

Both J_Meiser and Delboy52's V8 Supra conversions have between them had/have a selection of A340E, A341E and A343E boxes, yet neither have had this problem.

 

Before you pull out what remains of your hair, I suggest taking a look at how their speed sensors and speedo('s) are wired up?

[Shane]

I know that you have forgotten more about electrickery than I have ever leaned, however, this problem must be somewhere in the OE loom that you don't have?

 

Both J_Meiser and Delboy52's V8 Supra conversions have between them had/have a selection of A340E, A341E and A343E boxes, yet neither have had this problem.

 

Before you pull out what remains of your hair, I suggest taking a look at how their speed sensors and speedo('s) are wired up?

 

I hear what you are saying and Paul said the same. We spoke to Jay yesterday and his box came from a soarer and connections made from the 32pin orange body plug across to the ecu, thats not how the early UCF10 LS400s were done. For clarification I have looked at several wiring diagrams from the UCF10 and its clear that the No1 speed sensor output comes from the yellow cable and makes its way to the the speedo SP pin before moving on to the ODO and then returning to the ECU, this is bassically how Mike2JZ suggests in his first post in this thread. This is now how it is wired, we are simply seeing five times the amount of pulses from the LS400 sensor than the supra speedo is expecting to see. The yellow cable providing pulses from No1 sensor is connected to the wire from the original body loom on the supra which makes its way back to the SP connection of the speedo. To take any wiring errors out of the equation I hooked in a loose speedo I found direct to the LS loom wires from the gearbox and its the same. Doing a bit of research I found this: http://www.lextreme.com/forums/index.php?threads/w58-in-ls400-what-a-p-i-t-a.15612/ Although he has the opposite problem to us as he used the w58 drive arrangement (4 pulses per rev) with the ls400 cluster.

 

More info as to the wiring on P232 here: https://cardiagn.com/system-circuits-1990-ls400-ewd/ also P231 shows the signal going into a simple buffer in the original cluster and returning to the ecu.

 

 

I am confident, it should work as its wired no using No1 sensor for the speedo, its just getting the wrong info. Do you have a supra/soarer drive with gears we can try?

Edited November 12, 2018 by Shane (see edit history)

[David P]

I do have a GS300 tiptronic box that will have a no. 2 speed sensor 4.083 gear-pair same as N/A Supra & Soarer.

 

The only parts of this box that are any use to me are the prop-flange and sump, so you're welcome to the bits you want if you come and strip them?

 

I can't do this for you because my spine won't let me.

Edited November 12, 2018 by David P (see edit history)

[Shane]

I do have a GS300 tiptronic box that will have a no. 2 speed sensor 4.083 gear-pair same as N/A Supra & Soarer.

 

The only parts of this box that are any use to me are the prop-flange and sump, so you're welcome to the bits you want if you come and strip them?

 

I can't do this for you because my spine won't let me.

 

OK nice, thanks will tell Paul to get in touch or try and get over myself. Only thing is now though, as you know thats not going to be easy to change in situ.

 

Sorry to hear that, I too have been ill as you know and had a call back from the Docs this morning to say the latest Phlegm sample I provided on Friday morning has come back showing I still have an infection and I need to go back to the Docs today. Obviously compared to how ill I was I am sort of ok and getting by, but explains why I have been feeling so rough this weekend.

 

Hers a bit more info for you on the speedo. Early sensors fitted to LS400s put out around 350Hz at about 60mph and later ones (and I assume supras) put out around 65Hz

[David P]

However, if you are correct re. the Lexus ECU & no.2 speed-sensor gear-pair being radically different, you will result with a speedometer that works properly but gear-changes that don't?

 

I again suggest that you take a look at Mike or J's wiring before you start stripping Paul's box.

[Shane]

However, if you are correct re. the Lexus ECU & no.2 speed-sensor gear-pair being radically different, you will result with a speedometer that works properly but gear-changes that don't?

 

I again suggest that you take a look at Mike or J's wiring before you start stripping Paul's box.

 

No because its Speed sensor 2 that goes back to the ECU and controls the box and speed sensor 1 that does the speedo. To me at least it looks as though these are unconnected mecahnically and I dont intend to mess with the No.2 sensor. What am I missing?

[David P]

Maybe it's me that is missing?

 

Because the no. 2 speed sensor controls the speed at which gears-change, I have assumed that it also controls the speedometer.

 

You could confirm either way by disconnecting one then the other on your T.T. and see what happens?

[Shane]

Maybe it's me that is missing?

 

Because the no. 2 speed sensor controls the speed at which gears-change, I have assumed that it also controls the speedometer.

 

You could confirm either way by disconnecting one then the other on your T.T. and see what happens?

 

 

OK no thats not the case.

 

Sensor 2 does the gears, sensor 1 speedo. I incorectly tried to run the speedo from sensor 2 when we got the car running before I knew this. The car is changing beautifully as it is and I dont intend to touch sensor 2 or the wiring of this. Now its interesting you should suggest this. I have just been reading somehtiung that suggests the very reason the output from sensor 1 makes its way back to the box is as a back up should something go wrong with the output of sensor 2. The idea being that it throws a code and tries to use the output of sensor1 to get you home as the box doesnt like no info at all. Its interesting stuff and has been a steep learning curve.

[David P]

As I have never come across this issue, I have never looked into it.

 

Stripping the no.1 sensor will be an easy enough one 10mm bolt job, but I can't get at it because there's another box in the way.

 

Before I was a Spaz, I used to pick these things up with one hand.