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Discussion Starter #1 (Edited)
Can anyone tell me how to wire the pictured module ( link below) to my ECM without frying it?

NE555 Duty Ratio Adjustable Pulse Generator Adjustable Small Signal Generator DP | eBay

This is the only one I've found with a pulse frequency << 1 Hz. The other square-wave Ebay modules just have three pins (Vcc, GND, Vout) so easy enough to wire up but they all have a pulse frequency of 1Hz (minimum) which may not work as according to the IS300 Diagnostic manual the ECM will trigger a DTC for a noisy sensor if it gets more than 7 pulses / 15 seconds so I (ideally) need a pulse of 0.5Hz.

Unfortunately e-tronics isn't my strong point & despite hours of online research I still don't know how to wire the damn thing. I'm guessing that;
  • ECM Vcc pin wires to PCB module: IN / Vcc header pin
  • ECM E2 (GND) pin wires to PCB module: IN / GND pin
  • ECM PTNK (Signal in) pin wires to PCB module: OUT/ OUT pin.
Meaning that AFAIK* the PCB / Signal Generator module's
  • OUT/Vcc pin isn't used
  • OUT/GND pin isn't used. *Unsure; maybe this needs to be wired to chassis earth?
Can anyone confirm / refute this?

PS: I built* & wired in a breadboard from the below article into the IS300 ECM & it s-e-e-m-s to work (2-3 fairly short 20-30 min drives with no DTCs ) but I don't know how to turn it into a PCB so need an off-the-shelf solution.
*Changed C1=1mF (to lower min Hz) & C2=10nF

How to Build an Adjustable Square Wave Generator Circuit with a 555 Timer


Back Story:

I did an R154 manual swap on my (UK market RHD) 03 IS300 SX a couple of years ago.

Knowing the ATM ECM would throw codes looking for now-missing ATM solenoids and not wanting the hassle / expense of an aftermarket ECM I swapped in a Factory ECM from a USDM IS300 5speed Manual. Lexus only ever sold the MTM IS300 in the USA so a USDM ECM is (afaik) the only Factory ECM option for a manual-swapped IS300.

I figured it would be pretty much PnP. As it happens things didn't work out quite that easily.

As I found out after I completed the mechanical swap, in every other market IS300s run a simpler EVAP system without a fuel-tank pressure sensor; so the USDM ECM basically throws DTCs (0450, 0451) looking for a non-existing sensor.

Ever since the swap (18+ mths now) I've had an OBD2 scanner permanently connected & basically have to delete DTCs before every drive cycle. I've got the ritual down to ~ 30 sec but it's still a PITA.

I can't find anyone local that can hack the Lexus ECU to remove this code so aside from just pulling the lamp (I'm OCD so that's cheating) or importing / installing the entire USDM EVAP system (not happening) the only other thing I can think of is emulating / simulating the sensor; which shouldn't / wouldn't be a big deal (IF. I was an electronics whizz).

I tried to figure this out just after the swap but as electronics ( and TBH, basic circuit theory) isn't a strong point I got no-where & just put this in the too-hard basket.

Revisting this again to see if I can find a solution.
 

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2002 Lexus IS300
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If you are unplugging evap related items, why trick the ECU? Evap items unplugged aren’t going to affect anything for drivability. Unless you don’t like check engine lights on?
 

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Discussion Starter #4
Really the wrong section for this. This section is for all mobile electronics discussion including Navigation, video displays. But have you talked to Yury Baranov on Facebook?
I'd never heard of this guy until you mentioned him but thanks for the referral. He seems to offer a similar service to Phoenix Engine Management in the UK. I will message him but at present* I'm not keen on any solution that involves me posting an ECU across the World & back. (otherwise I would have sent my ECM to the UK company long ago).

* PS: Having said that I may end up doing that (sending an ECM overseas to reconfig for Manual) anyway as I may be doing a 1UZ swap in the next 6-12 months so want to avoid doing it twice.
 
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