No M-REL output from 1jzgte ecu

[ae864age]

Hi, I was wondering if someone could help me out with this problem.

I have just done a 1jz conversion into my 180sx, the engine, loom and ecu came from a ma61 that had the 1jz conversion done years ago, anyway I wired it all up using the modded loom, the ecu was wired up to a switched ignition power source and not through the m-rel and relay setup, it starts ok, runs and revs fine but idles low so I have been re wiring the loom to get the iscv working.

I am stuck at the moment because the m-rel pin on the ecu does not send out a +12v supply so I cant wire up a relay to supply power to the T1 and T12 pins, I have another ecu I have tried and it's the same.

I currently have the following wired up,

switched ignition +12v going to T13 IGSW
constant +12v going to T2 BATT
earth X24 E1

Also +12v switched to power igniter and coils.


I was wondering if you would know what could be the problem or if you have any ideas on what I can check to narrow it down.

Also, does the ecu power all sensors such as tps, iscv, map etc, and just the igniter and coils are powered from another source as I have it set up? Just wondering as the modded loom is a bit hard to get my head around.

Any help would be greatly appreciated.

[JP]

I had a similar issue with one of my jzx81 ECU's in a frontcut once, traced back the components from the MREL pin and found a blown transistor on the ECU. Replaced that and it was all good.

[wilbo666]

Sounds like you are using a JZA70 / JZX81 ECU?

Do you have your other grounds connected?

Other than that there really isn't much to it... is it possiable that you wiring has damaged the M-REL output of the ECUs (both of them?).

Can you try your ECUs in someone else's car?

Also, does the ecu power all sensors such as tps, iscv, map etc, and just the igniter and coils are powered from another source as I have it set up? Just wondering as the modded loom is a bit hard to get my head around.

The +5V sensors such as TPS, Map sensor, Air temp etc are powered from the ECU.

Injectors, Igniter & Coils are powered from Ignition.


Cheers
Wilbo

[ae864age]

Yeah sorry its a jza70 loom and ecu, the only other 1jz powered car I know the owner of down here in TAS is my brothers ra60, his runs a jzz30 loom and ecu though.

I have grounds to both sides of the block, the inlet manifold, a ground to the front turbo and also the back of the head, you can never have to many grounds lol.

I was thinking that the ECUs could of been damaged from power running through it the wrong way.

I will have another look at it tommorow and see if I can find any other causes for this issue.

Thanks for your help guys.

[George]

Check your schematic again. ECUs usually have low side switches in them, that is they break the ground circuit instead of supplying something with 12v.

If something's really blown inside your ECU and there's no way to fix it then run the MREL directly from IGSW. Following this way you wire relay's coil to GND and ignition switch. Switched terminals are then wired to the battery (via some 30A fuse) and consumers.

[wilbo666]

Check your schematic again. ECUs usually have low side switches in them, that is they break the ground circuit instead of supplying something with 12v.

I can quote a number of resources that show that it's a sourcing output (+12V)



e.g.
25 Engine Controls #2 - ECU/Outputs.pdf file size 495KB

If something's really blown inside your ECU and there's no way to fix it then run the MREL directly from IGSW. Following this way you wire relay's coil to GND and ignition switch. Switched terminals are then wired to the battery (via some 30A fuse) and consumers.

The only problem with that is the ISCV won't work correctly...

Might be an idea to add a Cap to make it a delay off Relay...

http://www.toymods.org.au/forums/showthread.php?t=54376

Cheers
Wilbo

[ae864age]

Thanks for the ideas, after checking both ECUs and not finding any problems I went back through the wiring and found it wasn't correct. I fixed that up then wired up a relay and tested it, but the m-rel +12v power to the relay switched off when I turned off the ignition. I put in my other ECU and that one worked correctly with the m-rel +12v staying on for just over a second after turning off the ignition.

At this point I thought I had finally got all the wiring done and I could get on with finishing the conversion but the iscv still has an issue, it has power to the two centre pins while the ignition is on and is still powered after turning off the ignition for a just over a second. I removed the iscv and tested it out of the car with another power source and it opens and closes fine.

I have no idea what to do now, I am a bit over it at the moment.

[takai]

You still need power to the ECU after it shuts off so that it can tell the ISCV to wind out gracefully.

Also, lots of older ECUs had a ground pull pin. Stuff like the 4AGE and GZE, and 7MGE had ground pull MREL. For some reason that changes with the JZ and UZ engines which all have 12v MREL pins.

[ae864age]

The m-rel does keep the relay going after turning off the ingition, the power coming from the relay is what is powering the ECU so the ECU still has power after the ignition is switched off for just over a second.

[ae864age]

well after leaving it for a few days I thought I will have another look at it and it seems to work fine now, I think the iscv may of been a bit stuck from not being used for a few years and has worked its way free after a few starts and works as it should, thanks for all your help.

[jameschia2722]

Thanks for the ideas, after checking both ECUs and not finding any problems I went back through the wiring and found it wasn't correct. I fixed that up then wired up a relay and tested it, but the m-rel +12v power to the relay switched off when I turned off the ignition. I put in my other ECU and that one worked correctly with the m-rel +12v staying on for just over a second after turning off the ignition.

At this point I thought I had finally got all the wiring done and I could get on with finishing the conversion but the iscv still has an issue, it has power to the two centre pins while the ignition is on and is still powered after turning off the ignition for a just over a second. I removed the iscv and tested it out of the car with another power source and it opens and closes fine.

I have no idea what to do now, I am a bit over it at the moment.

hi, i facing the problem with yours too (the m-rel +12v power to the relay switched off when I turned off the ignition.).
It doesnt hold on 1-2sencond to switch off.
Is it mean my ECU problem as well?? Pls help. it suffered me since a year when engine 1jzvvti convert to my jza80. SAD..