1JZ CEL light question. Is it just a 12+ current?

[Datsrboi]

My CEL light does not work. I have checked the Dash AND replaced the bulb but it still does not light up. Since I am not the original car I can not be certain whats wrong it it. Could be a bad dash although everything else on it works. I ended up pulling out my 1JZ that I had routed to the ECU. I did not splice it near the ECU but instead I spliced it on the Pre89 harness I had soldered to during the converting. I putted a bulb on the sliced end and grounded the bulb. I started the car and No light EVER came on. Does anyone know how to get it working again? Or how the CEl works?

 

[Evilempire1.3JZ-GTE]

The CEL is a LED light in the JZA70 with a resistor in series.
both the 1JZ & the 7M ecu applies a ground or a earth signal to the light both get 12 volts but the led one haves a resistor in series.

When your ecu detects a fault though it haves a ground output.

 

[Datsrboi]

So its just a ground. Explains why putting a bulb to it did not light it up.

 

[Evilempire1.3JZ-GTE]

100% correct each time the light comes on it because it gets a ground from the ecu.

Remember the computer on our engines is based on the simple 0vdc/5vdc 1/0 logic the 12vdc input gets re-biased to 5vdc all the digital inputs and outputs are 0-5vdc range including map signal & tps it sends a ground pulse out for rpms firing coils or injectors because the injectors & coils are always hot(+12VDC) on one side once the EFI relay closes(for the most part NSW switch etc effect this power distro also). it applies a ground also to your fuel pump etc.. so the way to check if your CEL light is on when it doesnt work is with a test light but with the one end applied to +12vdc instead of ground, then probe the ECU CEL pin.

 

[Datsrboi]

100% correct each time the light comes on it because it gets a ground from the ecu.

Remember the computer on our engines is based on the simple 0vdc/5vdc 1/0 logic the 12vdc input gets re-biased to 5vdc all the digital inputs and outputs are 0-5vdc range including map signal & tps it sends a ground pulse out for rpms firing coils or injectors because the injectors & coils are always hot(+12VDC) on one side once the EFI relay closes(for the most part NSW switch etc effect this power distro also). it applies a ground also to your fuel pump etc.. so the way to check if your CEL light is on when it doesnt work is with a test light but with the one end applied to +12vdc instead of ground, then probe the ECU CEL pin.

Thanks. I will get to that tonight. Its been driving me nuts.