Glow plug and CE lights

jimbote said:

i have to disagree about using incandescents... been running stock toyota cluster incans for almost six years no issues ... perhaps these circuits are meant to run inandescent bulbs for applications other than automotive...remember they are not part of the mkiv stock warning lamp system but seem to be vestiges or intended for use in other applications ... the ecm's even have a tach output that's not utilized in the 121 pin cars ... i am using a pnp transistor circuit correct my CEL operation so that isolates the bulb "current" but i don't feel it's necessary to protect the ecm

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Hasenwerk said:

Um you're just riding semantics with your disagreement . . .
You can't say, with a blanket, that you can run incandescent bulbs direct from an ECU. How many watts are we talking? Most cars, have tiny bulbs for the lights, however, there may be a combo out there that is too much current for the ECU and maybe not today or tomorrow, but one of these days you'll burn out the circuit in the ECU due to too much current. Hence, the smart idea to use an external circuit to handle the load and just let the ECU do the switching. If you don't think it's necessary to protect the ECU (even though you are protecting it with the transistor), that fine, however I will and will recommend that others do for the long term happiness of the ECU. The MOSFETs that I use can easily handle a 55W halogen if I wanted to - there no way the ECU was ever designed for that!

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