1jz ELS Wiring... Demister and Light signals

[Z2TT]

Hi Guys,

I notice that ECU's like 7m etc have 2 separate inputs, "LP" for Lamp signal and "ELS" for the Demister, from looking at the TSRM from the demist and headlight relay coils on the negative side a wire goes to the ECU "LP" and "ELS", so I take it the ELS expects a ground signal, could anybody confirm?

The second issue is, the 1jz ECU only has one pin "ELS", I was thinking to twist both the headlight and demister wires and wire them to the ELS Pin, but in this case whenever you turn on the headlights, it will ground out the demister and turn it on, Vice Versa.

Would using two diodes in the configuration below work? Excuse the poor drawings :

[RA35GT]

That should work if you flip the diodes around dood.

The only problem may be if the forward bias voltage of the diode is not low enough for the computer to register it as a low. (i would think it its low enough though)

[Z2TT]

Oh I thought the signal would only flow in the direction of the arrow like how I drew it, or is it different if your placing diodes on wires that get earthed?

Is there a certain type of diode I should use that you would recommend to not run any issues with the ECU not sensing when the wires are earthed?

Thanks

[RA35GT]

Conventional current will flow in the direction of the arrow (i.e. positive to negative) when the diode is forward biased. (Basically yes, its different because the signals are earths)

I'd give these a shot, they have low-ish forward voltages.
http://www.jaycar.com.au/productView...e&form=KEYWORD
http://www.jaycar.com.au/productView...e&form=KEYWORD

Alternatively you could also isolate them using small pcb relays.

[wilbo666]

Won't work that easily I don't think

ELS is active HIGH (+12V), yet looking at the MA70 7M wiring diagrams I have LP and DEF are active LOW... I'm not 100% sure I trust those wiring diagrams so I'd check to make sure your signals are Active LOW...

If they are active low you could use transistors or relays to invert the signals, or you could rewire the signals so they are active high...

26 Engine Controls #3 - Idle Speed Control.pdf file size 352KB - Page 14



Cheers
Wilbo

[Z2TT]

Well it's the original MK3 Factory Wiring Diagrams but I will check how the Demister and Headlamp signal wires behave on my current car.

Then again, what does the JZZ30 ECU Expect, power or ground? I haven't been able to find any JZZ30 wiring diagrams to trace the wire to see where it comes from.
So without having a complete JZZ30 Soarer to test whether the ECU accepts power or ground for the ELS I don't know.

[RA35GT]

just checked dood and the sc300 wiring diagram i have shows ELS to be active high with diodes as per pic wilbo posted above.

you'll have to check what signals the car puts out for them.

[Z2TT]

Hi, Thanks. I'll try and find out what the JZZ30 puts out to the ELS Pin.

If the jzz30 requires power I guess I will give it ground via a relay triggered by the grounds from the demist/headlights, and also add the diodes on the other way than what I posted on my pic.

[George]

just for a reference, ECU for 1jz-ge vvti 1998-2000 has two signals els1 and els2 and both of them are active high. Activating them is not very noticeable.

[wilbo666]

just checked dood and the sc300 wiring diagram i have shows ELS to be active high with diodes as per pic wilbo posted above.

you'll have to check what signals the car puts out for them.

JZZ30 Wiring diagram that I have shows the JZZ30 ELS to be active high.




I'd check what the existing signals that you have are still tho, as the MX83 diagram that I have shows an ELS pin which is active high

I think perhaps there was early and late 7m ECUs... One with the LP & DEF pins and the later with ELS? I'm not 100% sure to be honest, something to look into

Also as George says at the end of the day the ELS pin in my experience doesn't have a huge effect and I never even hooked it up on my 1JZ MA61 which was running a JZZ30 1JZGTE

Cheers
Wilbo

[RA35GT]

I thought SC300 = JZZ30 ? My bad if it isn't LOL.

[wilbo666]

I thought SC300 = JZZ30 ? My bad if it isn't LOL.

Close enough...(I quoted you to back you up )

But technically SC300 is Lexus and they never came with 1JZGTE!...

Cheers
Wilbo

[Z2TT]

Power it is then, Diodes and a Relay should do it.

[BMWTurbo]

How did you go with this?

I'm looking to do teh exact same thing this afternoon with my 2jz wiring. The JZA80 Supra appears to be the same as the Soarer with a high diode pack input.

I'm hoping it will idle the engine up a bit on thermo fan and headlights on. as without the A/C and with my larger injectors and voltaget drop at lower RPM I find the engine hunts.

[BMWTurbo]

So I tried sending high and low signals to this pin last night and I couldn't notice any lear change in any positions. I tried tieing it with a 10k resistor to earth and then sending a high signal and vice versa, still nothing noticeable.

However... I'm running in forced open loop, ie the Oxy Sensor totally removed from the ssytem, perhaps this els trigger ammends the idle mixtures to compensate for the additional load.

I do have the A/C idle up connected and this works perfectly, but even with this on I could see no change no matter what the els was fed.

I'm tempted to modify my A/C circuit to in effect allow the thermo-fan and headlights to idle the engine up when 'active' and then have a small circuit to send the compressor an output for the A/C input only.