O/D & A/C on for a 1JZTE ECU?

[ZZT231]

Hello All,

With the 1JZGTE ECU, can I supply 12v to OD2 on the ECU to engage overdrive (4th gear) on the auto and also connect 12v to the A/C to engage the A/C which I presume the ECU will send a signal to the compressor to turn it on?

Or does one, the other or both need to run on special circuits to supply lower voltage?

Any ideas or confirmation would be great.

Cheers.

[Robbos_Toyotas]

no they should both run off the ecu loom, and hook it up to the ecu as the switchable 12v for the compressor...why are you having problems with the auto not going into 4th? i thought in both cases of eco and pwr mode they go into 4th....well my a340e in the ma70 does anyway

[ZZT231]

no they should both run off the ecu loom, and hook it up to the ecu as the switchable 12v for the compressor...why are you having problems with the auto not going into 4th? i thought in both cases of eco and pwr mode they go into 4th....well my a340e in the ma70 does anyway

There may be a reason if the engine and gearbox originally didn't come from the car... The the car that got the engine did not orignally come with ECT as the 1JZGTE ECU controls both Engine and Auto Transmission...

Cheers.

[Mos]

With the 1JZGTE ECU, can I supply 12v to OD2 on the ECU to engage overdrive (4th gear) on the auto

The OD2 pin should have its own pullup to 12V, and if not, the O/D light will provide the pull up to 12V, so if the O/D Off switch is not engaged it should already have 12V on it. Of course if you have nothing connected to the pin you can measure what voltage is on it already - I would suspect 12V.



Under no circumstance should you supply 12V directly to that pin - through a resistor or light bulb is fine - don't forget the ECU grounds this pin to spit out error codes on the O/D Off light.

Also keep in mind that the status of this pin does NOT engage 4th gear per se - it merely allows the ECU to engaged it if it feels it's appropriate.

The only (electronic) way to force the box to go into a specific gear is to apply power directly to the correct solenoids in the box itself.

and also connect 12v to the A/C to engage the A/C which I presume the ECU will send a signal to the compressor to turn it on?

Depending on the engine the operation may differ, however in most 1JZ cases the A/C switch supplies 12V to the ECU through the pressure switches (on the A/C or AC1 pin - varies) and the ECU supplies a ground on the ACMG pin to the A/C relay solenoid - the other end of the A/C relay solenoid is supplied 12V from the A/C fuse, or sometimes from the Gauge fuse.



What is the application?

HTH.
Mos.

[Mos]

Depending on the engine the operation may differ, however in most 1JZ cases the A/C switch supplies 12V to the ECU (on the A/C or AC1 pin - varies) and the ECU supplies a ground on the ACMG pin to the A/C relay solenoid - the other end of the A/C relay solenoid is supplied 12V through the pressure switches, usually from the A/C fuse, but sometimes from the Gauge fuse.

Not usually quoting myself but there's one extra bit that I thought may be useful.
In some (usually older) A/C setups where the ECU can adjust the idle sufficiently (ie with stepper motor idle valves) the engine is merely "told" the A/C is running so it can turn up the idle to compensate for the extra load. In other setups, where the ECU itself can't idle up enough, the A/C turns on a VSV for idle up and tells the ECU that it just turned on the A/C.

In the setup described initially, where the ECU is "requested" to turn on the A/C, the ECU is able to increase the idle prior to turning on the A/C, and I guess in extreme situations the ECU can turn off the A/C.
If you have such an ECU, it is still OK, but not ideal, to just "tell" the ECU that the A/C is turned on and it will still turn up the idle - it just may stumble slightly when the compressor kicks in before the idle comes up to a proper level.

Mos.

[ZZT231]

It's fantastic... when i ground the OD2 wire, it doesn't allow the car to shift into 4th gear, when it's not grounded it's fantastic as it shifts in 4th (As I've been doing short driving in it on).

Though we don't know about the ECT switch now don't know where the wire is on the ECU Pinout...

As for A/C we are going to wire it up in a few hours and that should be it for the electrical, just have to get the hoses matched up and hooked up...

[CrUZida]

ECT switch is easy to test.

Shifter in 2, ECT off - car will take off from stationary in 1st.
Shifter in 2, ECT on - car will take off from stationary in 2nd.