how to check your ECU without removing it from car - by Yamae
03-29-24, 10:39 PM
#61
This is from the overall wiring diagram for a 1998 LS400. I cropped the area around the DLC1 (underhood data connector). It shows what is supposed to be there; I doubt this is helpful unless it can be determined what missing terminals are jumpered and the jumper can be relocated downstream of the DLC1.
Those are indeed the pinouts, nice find! But if it's down to jumping circuits because the wires aren't even there, you're probably right it's not too helpful. Well, I have a few spare capacitors if anyone needs them lol.
03-30-24, 04:55 PM
#62
I'm not an electronics expert so I wouldn't try the following without some kind of expert confirmation. I went through the following to clarify to myself what is actually being done at the DLC1.
In the original post:
- OP1 = Engine Temperature (coolant) Sensor
- E1 = The signal ground of the ECU
Coolant temperature sensor (OP1 = THW) ??
ECU Signal Ground
You can probably measure the ripple voltage the same way as is done at the DLC1 by back-probing the THW and E1 pinouts at the ECU with the capacitor attach to one of the DVM test leads. But you're still going to have to get to the ECU and the wiring harness. Is the effort worth the time? Might as well just go ahead, unplug the ECU and swap the capacitors.
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400fanboy (03-30-24)
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