Aircon wiring in a MX83 with 2JZ question

[ujw296]

Hi All

I am trying to wire up the A/C compressor on my 1990 MX83 Grande. Now fitted with 2JZ-GE.

I should have tried tracing the A/C wires in my old 7M loom but too late now.

I have a few wiring diagrams from my USDM Repair Manual and EWD of the A/C but I can't identify the B-W wire I have at connector B3 pin 8 and the T5 ECU A/C pin 2.

The ECU diagram does show the A/C pinout and states "From A/C mag clutch relay"?

I get continuity between both wires at the above connectors and then from either of them to a B-W mag clutch relay terminal?
At the A/C mag clutch relay I have a B-W, W-B and 2 L-B wires?

Does anyone know if the wire from pin 8 of the grey plug is the same one as the ECU A/C and relay wire?

Because there is no gas in the system till I get new hoses made I bypassed the Dual pressure switch (Hi and Low switch) and when the A/C button is turned on I get 12V+ on both the B3 pin 8 and the T5 ECU A/C pin 2.

If someone can tell me what to connect and disconnect in the attached image called AC plan so my aircon will work please it would be appreciated.

Thank you in advance.

[DavGT4]

Quick post to test if this comes up in the New Posts section...

[ujw296]

Latest:

Since bypassing the pressure switches I now have pin 8 of the Grey B3 plug connected to the compressor blue wire that pulls in the A/C mag clutch (the relay is working too :-) but still can't work out where the MX83 ECU T5 connector pin 2 goes in the 2JZ setup. I figure it used to send a signal to the ECU to increase the idle speed?
Anyone??????
Attached image shows the mag clutch wired up and pulling in.


Cheers

[wilbo666]

OK,

I will be honest, I'm not personally familiar with the MX83 and I don't personally have a set of proper wiring diagrams to look at... but that said,

It looks to me like the AC wire at the 7mge engine ECU (the 'MX83 ECU T5' connector, pin 2) is from the 'AC amplifier' (That's what is is called, but really as far as I am concerned it is the 'AC controller'), and tells the engine ECU that the AC is ON / OFF so it can raise the idle etc as you point out.


Anyway the setup that you really want is as follows...!

1) The OUTPUT of the AC amplifier that is currently triggering the AC Magnetic Clutch Relay (This should be the wire that connects to pin 3 of the relay) to needs to be rewired to go to the 2JZ engine ECU AC pin (Pin 34). (My understanding is that the AC Magnetic Clutch Relay is still following the AC switch OK, that is when you set the AC on the relay comes on, when you switch it off the relay goes off - is this correct?).

This will tell the 2JZ engine ECU that you want the AC turned on (obviously if it is too cold the AC controller might decide it needs to turn the AC off even if the switch is ON, etc so there is a bit more 'smarts' to it in the background...).

2) The AC/MG pin of the 2JZ engine ECU (Pin 23) needs to be wired to trigger the AC Magnetic Clutch Relay (This be pin 3 of the relay). Effectively this wire replaces the one we talked about in step 1) above.

This will turn the AC compressor on if the 2JZ engine ECU decides that it is OK to do so, i.e. the engine load isn't excessive, etc.


3) The output of the AC Magnetic Clutch relay (This should be pin 2 of the relay) needs to be connected to trigger the AC Magnetic Clutch on the AC Compressor on the side of the 2JZ engine (This should be pin 1 on the 2JZ engine loom, 90980-10897 plug).

It might be that Pin 2 of the AC Magnetic Clutch Relay on the MX83 side traces back to the "Grey 15 pin connector B3 pin 8" as you show on your latest drawing, but this is something I think you should confirm with a multimeter.




All the required pins on the 2JZ break out to plugs, so you just need to look at the info or worst case trace them from the engine ECU / AC compressor

Hope this helps.

Cheers
Wilbo

[ujw296]

Thank you yet again for a very informative reply.

I have the 1990 factory repair manual and EWD but I have yet to see 2 wiring diagrams the same or one that ties in with my car!

You are correct about AC Magnetic Clutch Relay still following the AC switch OK

I still wonder if maybe the B-W wire runs between ECU T5, B3 pin 8 and terminal 3 of the relay. I will strip a loom at the wreckers one fine day and check it out.
Wiring from the relay in the fuse box disappears straight into the loom with no physical connection to the compressor.

I did find a post with this info:

"Pin 34 on the 40 pin 2jz computer plug (black/blue trace) to pin 8 on the grey 15 pin Cressida plug

Pin 2 on the 22 pin Cressida ecu plug straight to the main power of the compressor" end quote.

I was concerned with there being 12V+ output at the 2 MX83 B-W wires with A/C on and connecting into the ECU

So nothing needs connecting from the old ECU T5 connector now as far as you can see?

I also read on your web information that pin 34 needs to be grounded so I did that and sure enough the revs came up. I put a meter on pin 23 while grounding 34 but got no voltage reading nor continuity to ground?

I will wire a relay in that utilises the 12V+ from pin 2 of the T5 ECU plug or pin 8 of the B3 plug and see what happens again at pin 23.

Cheers

[wilbo666]

What was wrong with wiring it how I suggested?... lol (Below is a more basic version of what I said above. It has some of the detail removed that is all...)

1) Existing Pin 3 of the AC Magnetic Clutch relay -> 2JZ engine ECU AC pin (Pin 34)

2) 2JZ engine ECU AC/MG (Pin 23) -> Pin 3 of the AC Magnetic Clutch relay

3) Pin 2 of the AC Magnetic Clutch relay connected to trigger the AC Magnetic Clutch on the AC Compressor on the side of the 2JZ engine / Pin 1 on the 2JZ engine loom, 90980-10897 plug.



Use a multimeter to trace back from the AC Magnetic Clutch relay Pin 1 to find which wire to connect in step 1.

I'd most likely connect Pin 2 of the AC Magnetic Clutch relay to the 2JZ, 90980-10987 plug in the engine bay. From the bottom of the relay as that will be closest to the plug on the 2JZ loom.

You shouldn't need to add other relays etc, use the existing one...

Don't make it harder for yourself than you need to....!



Cheers
Wilbo

[madmont]

I never connected the AC system to the Supra ECU and everything worked ok. Was connected as in your acmcsorted.jpg
Idle speed is controlled by the ISCV . In my manual Hilux I can take off on level ground in first gear and change through the gears to fourth without touching the accelerator pedal with the ECU maintaining the engine idle speed. Gets a bit jerky in fifth

[madmont]

Hi All

I I have a few wiring diagrams from my USDM Repair Manual and EWD of the A/C but I can't identify the B-W wire I have at connector B3 pin 8 and the T5 ECU A/C pin 2.

Thank you in advance.

If you look at this page I have identified the wires in the MX83 plugs
http://www.toymods.org.au/forums/tec...to-mx83-3.html

[ujw296]

Hi wilbo

The relay idea has gone in the bin as you advised.

I had times where the power wasn't happening when the A/C button was pressed but it turned out that it latches and illuminates but wasn't switching everytime.
Pain because it is part of the A/C control panel so I depinned the wires for now and ran a seperate switch.
While I was checking out the switch function I traced it's 2 wires and they go to pin 1 & pin 2 of the relay connector so I have amended and replaced the ACMC image pinouts. I was going on the pinouts printed on the relay not wiring diagrams.

The condensor fan relay was stuffed too after removing and testing it. New relay and fixed.

Cheers

[dumbass]

u should have just left all the ac wiring on the left hand inner guard on there as its not part of engine loom

then all u need to do is gas the system
then find the ac wire in the grey square plug behind glovebox
run that to the black/white wire on the 2j ac plu
there is 2 other wires on the 2j ac plug but they r for speed sensor for ac which is not used on mx83
I never bother with the acmg wire because it just adds more shit under dash so by the time u fit inhibitor relay
and tacho booster and fuel pump controller I don't like fitting another relay

the mx83 has only 1 wire for ac in the engine loom so its not that hard

[ujw296]

Here are the other pages of the MX83 USDM A/C wiring diagram to go along with the AC wiring 1 image in my first post for those who may want it.

[cresslux]

MX83 a/c wiring is VERY simple.

theres a black and white wire in the 22 pun body to ecu connector (get a pinout to conform as theres also the NSW wire but its thicker), this switched to B+ to tell the 7m to idle up
in the main engine harness to body connector, there is another thin wire that is black with a white stripe, this goes to the a/c magnetic clutch and is internally connected to the wire i mentioned first.

all you have to do for the a/c to work is hook either of these to the a/c clutch.

if you want the engine to idle up, then you need to use this wire to switch a relay to GROUND the ecu a/c pin, and if you want the ecu to have control (WOT a/c cutout etc) then the ACMG pin will go to ground when you ground the AC pin, so you can sue that to trigger a relay for the a/c clutch.

[ujw296]

Many thanks to wilbo666, madmont and cresslux.

The condensor fan relay was stuffed and the A/C on/off switch was intermittent now stuffed! It was latching & illuminating though? Didn't help troubleshooting :-)

If I ground pin 23 the idle up works no probs but I cannot get any sort of reading off pin 34 regardless (continuity to ground or a voltage)??


So as madmont and cresslux have suggested I have wired up pin wire # 8 to pull in the compressor and the MX83 T5 ECU wire is wired to a relay socket to switch pin 23 to ground and kicks in the idle up nicely if I need it. (will see how the idle is when the system is gassed).

I will look for a working A/C control panel and in the meantime I have de-pinned wire 7/12 & 8/12 and run the wires to where I can mount a different switch for now.

FYI: A/C switch is pin 7 and 8 and shows up as 7/12 & 8/12 or 7 & 8 CONNECTOR B on different wiring diagrams. See attached.
madmont sent me the 2JZ A/C pin voltages too, see attached.

I had to also wire up the ECT pattern switch to a relay to change it from positive to negative switching too, thanks madmont.

I will attack it all again when I get another control panel and try the hook it up as wilbo suggests if pin 34 makes any sense.

[ujw296]

Anyone with a MX83 Grande A/C Climate control panel in S.A. as pictured.
Thanks

[dumbass]

u need to make sure u wire ac wire up correctly on 2js

aristo and supra 2js have different inputs
one is 12v trig other is ground trig

wiring up the acmg is good idea but just takes awhile to do it nicely without having wires running loosely thru engine bay