UZS157 1uz ecu (89661-3a310, non-immobilized) - pictures and info

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*Title should read UZS157

Hi all,

I got my hands on a Crown Majesta non-immobilized ECU. Luckily, it had the three rightmost plugs still in it, so I'm able to see which wires were connected from factory as well as the wire colours.

Click on the images below for full size.







At first, I thought that these plugs might have been out of a different model, but then I found these pictures that confirmed they are correct.



I read that this ECU has a similar (if not same) pinout as the Celsior/LS400, however after looking at it, some of the wires are in different places. For now I'm focusing on the rightmost plug (where immo wires would have been).

This motor did not have a hydraulic fan, and the ECU does not have an immobilizer or MPX bus, so many of the wires are gone, but it still seems a bit odd (and minimal). Below is what you would expect to see on a Celsior.

If I use the Celsior pinout, then the wires should be as follows:



1 - green - D
10 - red - ??
14 - black/brown - STI-
16 - blue/white - L
25 - green/orage - 4
26 - violet/green - RL


3 - IMLD
4 - EOM
5 - HP
6 - TH-
7 - TH+
8 - SOL-
9 - SOL+
11 - MPX1
12 - CCV
17 - TXCT
18 - CODE
19 - RXCK
20 - KSW
21 - LCK1
22 - TAM
23 - PRE
24 - MPX2

  1. What is the red #10 wire?
  2. Does it make sense that this ECU is missing KSW due to no immobilizer?
  3. What about the HP, LCK1, PRE, and TAM pins for the A/C?
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These a/c pins would not make sense without MPX bus
Looks like there must be AC1, AC2 pins somewhere, like it was with older ECUs
As well as ELS1,ELS2 pins

You can try using Soarer diagrams. SC400 that had 4.0 vvti engine had no MPX bus either
Hi @George_R ,

A bit late, but I did some digging into the SC400 VVTi diagram.

I found that the SC400 has both AC and ELS pins - ELS is at D12, AC is at D25.

The D connector on the SC400 diagram is the A connector on the LS400 diagram.

On the LS400, A12 is unused I believe (nice!) and A25 is MOL (oil level switch). Interestingly enough, I could not find an MOL pin on the SC400 diagram, although the SC400 does have an oil level sensor. I can't say with certainty that this is the AC pin on the 3A310, but it's possible. There were a few "extra" wires on the 3A310 connectors, so it could be any of them.

I also noticed that the SC400 has DI and FPC pins instead of FPR and FC. The UZS157 doesn't have a fuel pump ECU, so I assume the 3A310 uses FPR/FC.

Let me know your thoughts.


  • SC400 1UZ-FE VVTi ECU Diagram.pdf
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  • LS400 1UZ-FE VVTi ECU Diagram.pdf
    932.7 KB · Views: 112
We don't have a single SC400 vvti here, so I didn't do any research on them
They may have no MPX and analogue inputs only, just like the UZS15x which surely have no MPX

10 - red - This pin activates the Cruise Control indicator on the instrument cluster.
10 - красный - подключить на комбинацию приборов: индикатор круиз контроля. Активный уровень -, неактивный +
В этом блоке управления нет иммобилайзера.
There is no immobilizer in this control unit.
Завтра картинку скину. Но там не все контакты расписаны. Двигатель с таким мозгом запустили по схеме для UСF20.
Tomorrow I'll take a picture. But there are not all contacts are painted. An engine with such a brain was launched according to the scheme for UCF20.
Как я понял, в этом мозге пин АС служит только для поднятия оборотов и включения муфты кондиционера чере ACMG, так как пина LCK нет.
As I understand it, in this brain the pin speaker serves only to raise the speed and turn on the ACMG clutch of the air conditioner, since there is no LCK pin.
На днях закончили установку этого двигателя в Тойоту Прадо 120, вместо дизельного.
Recently completed the installation of this engine in the Toyota Prado 120, instead of diesel.
Для корректного переключения АКПП необходимо чтобы на пин RSPD приходил сигнал скорости с комбинации приборов, аналогичный тому который передается непосредственно в мозг от датчика скорости. При подключении к диагностическому разъёму в движении будет видно две скорости, надо чтобы они совпадали, иначи переключения АКПП некорректные или коробка встанет в аварийный режим.
For correct automatic transmission switching, it is necessary that the speed signal from the instrument cluster, similar to that transmitted directly to the brain from the speed sensor, comes to the RSPD pin. When connected to the diagnostic connector in motion, two speeds will be visible, it is necessary that they coincide, and the automatic transmission shift means incorrect or the box will get into emergency mode.
Hi! Maybe someone have original japanese electrical wiring manual for Toyota Crown Majesta UZS151 UZS155 UZS157?

It looks like that original manual number is 6745803.

It should contain all the info about factory wiring for that car.

Can't find something else about that manual.